2020 Spring Meeting
Nanomaterials and advanced characterizationI
Laser material processing: from fundamental interactions to innovative applications
This laser symposium will bring together leading academic scientists, researchers and laser users and manufacturers for an intensive exchange and share of their experiences on recent progress in Laser Science and Technology, in particular in the fields of laser materials processing and synthesis. It also gives room to present and discuss the most recent innovations, trends, and concerns, practical challenges from nanofabrication via energy to biomedicine.
This symposium will cover all new advances in laser-matter interaction coupled to recent applications of emerging materials, their fabrication and application. The main objective is to update the basic phenomena involved in the interaction of the wide range of laser systems, where still new and efficient devices including smart optics, high and low repetition rate processing as well as high and low beam fluences come up regularly. The symposium will consider recent progress in laser-assisted additive fabrication (SLS, SLM), laser and intense light applications in printed electronics, laser-based nanofabrication, nano-LIPSS formation, laser lift of biological materials and systems and more emerging techniques such as laser synthesis of nanoparticles in liquids, and will thus offer a unique opportunity for researchers from Europe and worldwide areas to discuss their results in a friendly, interactive, and engaging atmosphere. Laser techniques will facilitate environmental and eco-design through the useful processing of photovoltaic cells, photocatalytic materials, thermoelectric materials and devices, micro and nanosystems for energy storage and conversion. A special focus will be given for these ‘hot’ topics. All contributions on laser interaction with hard, soft and smart materials, targeting future applications from nanoenergy to biomedicine as well as recent progress on the fundamental mechanisms are welcome. The symposium Laser Material Processing: From fundamental interactions to innovative applications will provide a platform to establish interdisciplinary international research collaborations between scientists working in the field of laser-matter interaction.
The symposium will consist of invited presentations by leading scientists in their respective fields and contributed papers for oral and poster presentations. Special emphasis will be given to young scientists presenting high quality research papers. The contributions should concern, but are not limited to the topics listed below.
Hot topics to be covered by the symposium:
- Lasers in nanotechnology and nanofabrication: electronics, magnetics, photonics, sensorics;
- Lasers in environmental technology, decarbonized energy materials, storage, and sustainability;
- Laser 3D micro-structuring: MEMS, MOEMS, photonic crystals, photonic applications; biological devices
- Laser processing of 2D materials;
- Ultra-short, ultra-high power laser interaction with matter: fundamentals and applications;
- Subwavelength laser produced structures for smart optical, electro-optical, electronic and biological devices;
- Laser-induced nanostructures: from theory to applications;
- Lasers for large-scale fabrication: 3D printing, roll-to-roll processing, printed electronics;
- Photonic curing: methods and emerging applications;
- Laser process monitoring and control, time resolved diagnostics, advanced characterization of materials.
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Lasers in additive manufacturing I : Mykola VINNICHENKO
Authors : Gontad, F.* (1), Vidal-álvarez, S. (1), Otero, N. (1), Arnoux, C. (2), Monnerau, C. (2), Baldeck, P. (2), Carlier, Q. (3), Pérez-Covarrubias, L. (3), Heggarty, K. (3), Hilbert F. (4), Wiedenmann, J. (4), Mantei, W. (4), Houbertz, R. (4), Romero-Romero, P. (1)
Affiliations : (1)AIMEN Technology Centre, O Porriño, ES36418, Pontevedra, Spain (2) Univ Lyon, Ens de Lyon, CNRS UMR 5182, UCBL, Laboratoire de Chimie, 46 Allée d’Italie 69007, Lyon, France (3) Telecom Bretagne, Department of Optic, IMT-Atlantique, Technopole Brest-Iroise , CS 83818,29285 BREST, France (4) Multiphoton Optics GmbH, Friedrich-Bergius-Ring 15, 97076 Wuerzburg, Germany * lead presenter
Resume : Two Photon induced photopolymerization (TPP) is a very well-known microfabrication technique that allows the fabrication with many advantages such as 3D freeform fabrication due to its high degree of freedom. For many applications, especially in industrial use, a higher speed is desired for TPP fabrication. One possibility to speed up the fabrication is the use of parallelization optics, which could allow to decrease dramatically the TPP fabrication times. TPP parallelization requires the development of optical setups that accurately split the beam in order to fabricate with multiple beams. At the same time, all characteristics have to be maintained that make single beam TPP such an excellent fabrication technology. Furthermore, the photochemistry involved in the process must be also refined in order to increase the resin sensitivity, while minimizing the influence of each fabrication voxel on the neighbour photochemical reactions. In this presentation, a review of the approaches used for parallel TPP fabrication, as well as the different resins produced to such aim, developed within the frame of the European PHENOmenon project will be presented and discussed. The use of static and dynamic beam splitting will be introduced, discussing their advantages and drawbacks, proposing alternatives for the optimization of the technique for the parallel fabrication of complex 3D structures.
Authors : George S. Nolas,1 Saniya LeBlanc,2 Haidong Zhang,2 Ryan Welch,2 Bengisu Sisikand2 and Dean Hobbis1
Affiliations : 1. Department of Physics, University of South Florida, Tampa, Florida 33620, USA 2. Department of Mechanical & Aerospace Engineering, The George Washington University, Washington DC 20052, USA
Resume : Traditional thermoelectric device manufacturing uses bulk material processing with machining, assembly, and integration steps that lead to material waste and performance limitations, as well as restricts the flexibility in designing the geometry of thermoelectric modules. Additive manufacturing can overcome these challenges and expands the materials capability to enable new materials research in addition to device develop utilizing existing thermoelectric materials. We successfully employ selective laser assisted additive manufacturing, also known as additive fabrication, to semiconductor thermoelectric materials and enable new geometries and architectures, nano- to meso-scale structuring, and material-to-device integration. In this talk I will describe our recent progress in laser-based additive manufacturing of tellurides and silicides. I will also discuss the impact of laser processing on microstructure and phase, and characterize the key thermoelectric properties (Seebeck coefficient, electrical resistivity, thermal conductivity) as a function of temperature for materials processed via laser additive manufacturing. Finally, the impact of novel geometries, which can have a substantial effect on thermoelectric device performance, using multi-physics modeling is presented.
Authors : Renheng Bo, Mahdiar Taheri, Hongjun Chen, Jonathan Bradford, Nunzio Motta, Takuya Tsuzuki, Paolo Falcaro and Antonio Tricoli
Affiliations : Renheng Bo, Mahdiar Taheri, Hongjun Chen, Takuya Tsuzuki, Antonio Tricoli: Australian National University, Canberra, Australia Jonathan Bradford, Nunzio Motta: QUT, Brisbane, Australia Paolo Falcaro: Gratz University, Gratz, Austria
Resume : Geometrical structuring of monolithic metal-organic frameworks (MOFs) components is required for their effective practical implementation in many areas, including electronic devices, gas storage/separation, catalysis, energy storage as well as bio-medical applications. Despite progress, an approach for the precise patterning of MOF functional geometries such as channels, wells and micro-membranes is lacking. Here, we report a facile and flexible concept for the writing of arbitrary complex MOFs patterns with micro-to-macro dimensions on wafer-scale. Our method relies on the engineering of paper-like sheets of precursor metal oxide nanoparticles that are loosely bonded to a supporting substrate and can be easily removed by laser ablation, resulting in well-defined high-aspect ratio patterns. Gas-phase conversions of these patterned ceramic nanoparticle sheets result in monolithic MOFs with arbitrarily shaped geometries and thickness of up to hundreds of micrometres. We demonstrate diverse patterns of Zeolitic Imidazolate Framework-8 (ZIF-8) on surface of several cm2, including printed letters, circular disk arrays, interconnected “impounding reservoir”, geometric drawings, superimposed “zig-zag”, perpendicular and serpentine channels. A vastly pure ZIF-8 composition of the resulting patterns is confirmed by a series physical and chemical characterization techniques, with a small laser-affected area near the patterned edge. This paper-like precursor-writing approach provides novel opportunities for the design of MOFs devices with application ranging from micro-fluidics to enzymatic reactors and renewable energy systems.
Laser processing of materials I : Maria DINESCU
Authors : F. Toldra-Reig, V. H. Nguyen, C. Masse de la Huerta, H. Santos, S. Quessada, L. A. Angurel, L. C. Estepa, G. F. de la Fuente, D. Muñoz-Rojas
Affiliations : F. Toldra-Reig (Univ. Grenoble Alpes, CNRS, Grenoble INP, LMGP, F-38000 Grenoble, France); V. H. Nguyen (Univ. Grenoble Alpes, CNRS, Grenoble INP, LMGP, F-38000 Grenoble, France); C. Masse de la Huerta (Univ. Grenoble Alpes, CNRS, Grenoble INP, LMGP, F-38000 Grenoble, France);H. Santos (ICMA(CSIC-Univ. Zaragoza), 50018, Zaragoza, Spain); S. Quessada (Univ. Grenoble Alpes, CNRS, Grenoble INP, LMGP, F-38000 Grenoble, France); L. A. Angurel (Univ. Grenoble Alpes, CNRS, Grenoble INP, LMGP, F-38000 Grenoble, France); L. C. Estepa (Univ. Grenoble Alpes, CNRS, Grenoble INP, LMGP, F-38000 Grenoble, France); G. F. de la Fuente (Univ. Grenoble Alpes, CNRS, Grenoble INP, LMGP, F-38000 Grenoble, France); D. Muñoz-Rojas (Univ. Grenoble Alpes, CNRS, Grenoble INP, LMGP, F-38000 Grenoble, France)
Resume : Methods based on laser processing of materials are evolving fast over the years as they provide unequaled spatial and temporal control, allowing to achieve transformations at interfaces on solids under air, controlled atmospheres or liquid environments. These methods are employed in a vast number of fields, including photonics, optics and electronics, to synthesis, nanofabrication and functionalization of materials, among others. The use of lasers provide a choice of emission parameters, such as wavelength, pulsed or continuous wave mode and pulse width, together with the use of optomechanical means to scan in beam or line fashion. These are ideal in order to trigger thermally activated physico-chemical phenomena which are not available with alternative methods that normally involve high power consumption, long processing times, energy losses and incompatibility with thermally sensitive substrates. In this communication, we will introduce the Laser Ablation Backwriting (LAB) method and we will show how it can be used to perform dry chemical reactions with spatial control and at room temperature, yielding a selective modification of the substrate bulk and/or surface. The latter may result, for example, in modulation of the wettability of surfaces for various applications, as well as in the facile fabrication of optical diffraction gratings. This research is supported by the project SPRINT (EU H2020-FETOPEN 801464).
Authors : Vittorio Scardaci, Luca Fichera, Nunzio Tuccitto, Giuseppe Compagnini
Affiliations : Dipartimento di Scienze Chimiche, Università degli Studi di Catania, Catania, Italy
Resume : Laser scribing has been proposed as a method for transforming polymers or graphene oxide into graphene. Such materials were then used for applications in sensing and electronics. Here, we investigate laser modification of graphene oxide in both air and controlled atmosphere, like Nitrogen, Argon and an Ar-H2 mixture. The degree of conversion was investigated against different irradiation conditions by Raman spectroscopy. We determine that Argon and Ar-H2 mixture produce the highest quality reduced graphene oxide (RGO). Such material has been tested for sensing against relative humidity, with those produced in Argon yielding the highest sensitivity and the best overall performance
Authors : Stefania Sandoval,1 Dejan Kepić,1 Ángel Pérez del Pino,1 Enikö György,1 Elzbieta Pach,2 Andrés Gómez,1 Markus Martincic,1 Martin Pfannmoeller,3 Gustaaf Van Tendeloo,3 Belén Ballesteros,2 Gerard Tobias.1
Affiliations : 1 Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus de la UAB, 08193 Bellaterra (Barcelona), Spain. 2 Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and The Barcelona Institute of Science and Technology. 3 Electron Microscopy for Materials Research (EMAT), University of Antwerp, Groenenborgerlaan 171, 2020 Antwerp, Belgium.
Resume : The particular properties of 2D layered nanomaterials are attractive for diverse applications including the miniaturisation of electronic devices. Using a molten phase approach, we synthesised tubular van der Waals heterostructures by growing single-layered inorganic nanotubes (SLINTs) of metal halides within MWCNTs. The confined materials adopt different structures and the formation of SLINTs is greatly enhanced by increasing the treatment temperature. We also report on a simple, versatile, ultrafast and energy efficient laser-assisted strategy that allows the tailored synthesis of crystalline SLINTs in the cavities of CNTs. In contrast to the thermal approach, this strategy is highly selective toward the growth of monolayers forming tubular van der Waals structures. In case of PbI2-NT@MWCNTs, the irradiated bulk material bearing the nanotubes reveals a decrease of the resistivity as well as a significant increase in the current flow upon illumination. Both effects are attributed to the presence of single-walled lead iodide nanotubes in the cavities of carbon nanotubes, which dominate the properties of the whole matrix.  S. Sandoval, E. Pach, B. Ballesteros, G. Tobias, Carbon, 2017, 123, 129-134.  M. Martincic, S. Vranic, E. Pach, S. Sandoval, B. Ballesteros, K. Kostarelos, G. Tobias, Carbon, 2019, 141, 782-793.  S. Sandoval, D. Kepić, Á. Pérez del Pino, E. György, A. Gómez, M. Pfannmoeller, G.V. Tendeloo, B. Ballesteros, G. Tobias, ACS Nano, 12, 2018, 6648-6656.
Authors : Yasmín Esqueda-Barron 1, Pablo García Lebière 1, Ángel Pérez del Pino 1, Enikö György 1, Joan Marti-Gonzalez 2 3, Roger Amade Rovira 2 3, Enric Bertran-Serra 2 3
Affiliations : 1 Institute of Materials Science of Barcelona (ICMAB – CSIC), C/ dels til·lers, Campus Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain; 2 Department of Applied Physics, Universitat de Barcelona, C/ Martí i Franquès, 1, 08028 Barcelona, Catalunya, Spain; 3 ENPHOCAMAT Group, Institute of Nanoscience and Nanotechnology (IN2UB), Universitat de Barcelona
Resume : Carbon-based nanocomposites are meant to lead the electrochemical energy storage area. In this work, we focus on the performance of graphene nanowalls (GNWs) mats grown on stainless-steel by chemical vapor deposition as electrodes for supercapacitor devices. In order to improve the GNWs intrinsic capacitance, we grew transition metal oxides nanoparticles (TMO NPs) on the graphene surface using an innovative optical technique based in pulsed laser radiation. For the electrode fabrication, the GNWs layers were laser processed immersed in aqueous solutions containing Ni-, Mn- and Ce-based organometallic salt precursors. Photothermal processes led to a substantial increase of the local temperature of the system allowing the crystallization of the TMO NPs on the surface of the GNW sheets. The electrochemical performance of the electrodes was characterized using cyclic voltammetry, galvanostatic charge - discharge, and electrochemical impedance spectroscopy. The morphology and crystallographic nature of the phases were determined by means of transmission and scanning electron microscopies, besides Raman spectroscopy. The results showed exceptional augment of the electrodes capacitance, more than two orders of magnitude, with incorporation of the TMO NPs especially in the case of the Ni oxide nanoparticles. The relationship between the structural nature of the laser-processed electrodes and their functional properties will be discussed.
Authors : Ahmed Al-Kattan
Affiliations : Aix-Marseille University, LP3 Laboratory, Marseille, France
Resume : Driven by surface cleanness, unique physical and chemical properties, bare (ligand-free) laser- synthesized nanoparticles (NPs) are now in the focus of intensive researches in a wide range of applications including environment, catalysis and biomedicine. Indeed, based on the interaction of ultrafast laser beam in liquid ambiance (e.g., aqueous solution) with a solid target material, this process leads naturally to the formation of spherical NPs with modulate physicochemical properties including diameter and size dispersion, surface chemistry and oxidation rate . Recently, in our group we have thus demonstrated the possibility to elaborate ultraclean and very stable colloidal suspension of AuNPs and SiNPs with unique physicochemical properties for biomedical applications [1-3]. For instance, we have shown the possibility to modulate the dissolution behavior of SiNPs by varying the amount of dissolved oxygen in water . We have also evidenced the complete safety properties of AuNPs and SiNPs using in vivo nude mice animal model [4,5]. As one of the major result, we shown that the SiNPs can be also exploited as significant sensitizers of radiofrequency (RF)-induced hyperthermia on Lewis lung carcinoma with efficient tumor inhibition at relative low concentration . Very recently, we have also elaborated promising alternative plasmonic tools based on TiN NPs for potential photothermal therapy modalities . Beside conventional additives mainly made-it by chemical way, we have also started to explore such bare laser synthesized NPs as novel functional additives for tissue engineering applications .  A. Al-Kattan et al, IJMS, 2018, 19(6), 1563)  A. Al-Kattan et al, J. Mater. Chem. B, 2016, 4, 78523  F. Correard et al, Int. J. Nanomed., 2014, 9, 54152  T. Baati et al, Sci. Rep., 2016, 6, 25400  A.L. Bailly et al, Sci. Rep., 2019, 9, 1258  K.P. Tamarov et al, Sci. Rep., 2014, 4, 7034  A. Popov et al, Sci Rep, 2019, 9, 1194  A. Al-Kattan et al, RSC Adv., 2017, 7, 31759
Authors : Emmanuel Stratakis (1,2)
Affiliations : (1) Foundation for Research and Technology - Hellas (F.O.R.T.H.), Institute of Electronic Structure and Laser (I.E.S.L.), Heraklion, Crete, Greece; (2) Physics Department, University of Crete, Heraklion, Crete, Greece
Resume : This presentation will focus on the application of advanced ultrafast photonic approaches for novel materials synthesis, as well as for the development of advanced photonic techniques to probe at the nanoscale, which are issues of great interest in current materials science and engineering research. In particular, Nature inspires us in tailoring unique surface properties based on synergetic effects of chemical composition and multiscale surface morphology. We show that highly controllable, biomimetic structures, exhibiting multifunctional water repellent, anti-reflection, friction reduction and photoresponsive properties can be directly written on metallic and dielectric surfaces upon processing with femtosecond laser beams of tailored polarization. It is shown that biomimetic laser structuring is a versatile method to tune neuronal cell adhesion, proliferation and orientation and can be promising for biomaterial scaffolds for neural tissue regeneration. The second part of the presentation will focus on the application of advanced ultrafast laser based techniques for the synthesis and diagnostics of materials and components in photovoltaic, light emitting, chemical sensing and energy storage systems. In particular, the pulsed laser assisted fabrication of transparent graphene electrodes and interlayers for flexible photovoltaic devices, is demonstrated. Furthermore, we present a fast non-destructive and roll-to-roll compatible photochemical method for the doping of graphene.
Laser processing techniques and applications I : Jörn BONSE
Authors : Driffa GUERFA, Iryna GOZHYK, Ekaterina BUROV, Bertrand POUMELLEC, Matthieu LANCRY
Affiliations : Saint Gobain recherche, Aubervillers & ICMMO, Orsay ; Saint Gobain recherche, Aubervillers; Saint Gobain recherche, Aubervillers; ICMMO, Orsay; ICMMO, Orsay
Resume : In glass industry thin film stacks are deposit on glass in order to provide additional functions to glazing. In some cases, oven baking or laser induced heat treatment is used to crystallize, densify, etc. these films. But what is the impact of such local laser heating on the glass substrate? To answer this question, the temporal evolution of 3D temperature distribution in the substrate must be known. In classic case of oven baking, temperature can be considered homogeneous within the sample while the cooling rate is limited by the thermal inertia of the equipment. In case of laser treatment of the supported thin film, the substrate is locally heated by heat extraction from the film. The temperature distribution is not homogenous and the cooling rate is more rapid, thereby glass relaxation is different from classic heating case. Spatial gradient of physicochemical properties of glass, such as density, refractive index, can be studied through the fictive temperature (Tf), glass-specific parameter describing the degree of order of liquid during its cooling. The goal is to get a mapping of the Tf and to link it to physicochemical parameters in order to follow their modifications This work presents a study of Tf in glass substrate due to the UV ns laser-induced heating of the weakly absorbent thin film on top of the substrate. Numerical study of Tf is performed with finite elements simulations and the experimental validation of the model is carried out by a Raman spectroscopy study.
Authors : Manuel Oliva-Ramirez, Philipp Schade, Dong Wang, Peter Schaaf.
Affiliations : Chair Materials for Electrical Engineering and Electronics, Institute of Materials Science and Engineering and Institute of Micro- and Nanotechnologies MacroNano®, TU-Ilmenau, 98693-Ilmenau, Germany. https://www.tu-ilmenau.de/en/wt-wet/
Resume : The evolution of electronic systems towards miniaturization went a step forward by including nanofabrication techniques. In particular, thin films play a very important role in this miniaturization as active and responsive layers but also as electronics components in the form of electronic contacts. However, metallic thin films are metastable in the as-deposited state and they tend to agglomerate (or dewet) when their atoms have enough mobility even in the solid state. This phenomena, known as Solid State Dewetting (SSD), has long hampered electronic microsystems since it limits the reliability of the films and jeopardize the proper functioning of the systems, especially when they operate at high temperatures. In the present work, we studied the evolution of the electrical properties of Au thin films after thermal annealing at different temperatures. The samples were treated by rapid annealing and subsequent fast cooling to freeze the evolution between treatments and to provide a real insight of the morphology state. The changes in the electrical properties were identified with the morphological stages of SSD (nucleation of voids, rim pinch-off, fingering, breaking of the connectivity), and the relationship between the resistivity and the microstructure unraveled.
Authors : De Bonis A. (1); Curcio M. (1); Santagata A. (2); Galasso A.(1); Teghil R. (1)
Affiliations : (1) Dipartimento di Scienze, Università della Basilicata, Potenza, Italy (2) ISM-CNR, Tito Scalo (PZ), Italy
Resume : Transition metal oxides (TMO) are a class of very interesting materials due to their optical, magnetic and catalytic properties. These properties are strongly related to oxides structure and morphology and a synthetic route that allows to control size and composition of obtained nanoparticles is essential. In last years, laser ablation in liquid (LAL) has been proposed as a simple technique to produce metal oxide nanoparticles without the use of any toxic reagents. However, nanomaterials obtained by LAL often present several phases and wide size distribution. The successive laser irradiation of the colloidal solution obtained by LAL can be a suitable strategy to overcome these drawbacks. We have ablated some transition metals (Fe, Mo, Ta and W) in water with a femtosecond laser source (800nm, 100fs, 1kHz) to obtain TMOs and we have studied the effects on their morphology and composition of nanoparticles laser melting by irradiating the colloidal solutions with a nanosecond laser source (532nm, 7ns, 10Hz). The obtained materials have been characterized by microscopic, spectroscopic and diffractometric techniques.
Authors : Owen Ernst, David Uebel, Felix Lange, and Torsten Boeck
Affiliations : Leibniz-Institut für Kristallzüchtung, Max-Born-Str. 2, D-12489 Berlin, Germany
Resume : New approaches using laser technologies are promising to improve bottom-up growth processes and elucidate the underlying mechanisms. In this research, a nanosecond laser is used to interact with ultra-thin metal films and induce a controlled dewetting process. The high energy pulsing allows for precise isolation of intermediate stage of dewetting. All stages can be observed: From the destabilization of the film to the generation of initial fluctuations of matter and the formation of nanoparticles. The influence of roughness and morphology of the underlying material and the layer thickness were also studied. This provides new insights into the mechanisms of dewetting processes and particle formation, which can be used for the development of novel 2D and 3D bottom-up structuring processes. Two different material systems with two different applications serve as first examples. One example is gold on silicon and silicon oxide, which can be used as a solving material for the manufacture of thermoelectric devices. Indium on molybdenum, which can be functionalized for photovoltaic applications, is the other example mentioned. Both the theoretical description of the laser-thin film interaction and the practical application will be examined in detail.
Authors : Skobelkina A.V.*(1), Kashaev F.V.(1), Zabotnov S.V.(1), Kirillin M.Yu.(2), Kurakina D.A. (2), Khilov A.V.(2), Sergeeva E.A.(1,2), Chura O.O. (1,3), Kolchin A.V.(1), Kaminskaya T.P.(1), Presnov D.E.(1,4,5), Golovan L.A.(1), and Kashkarov P.K.(1)
Affiliations : (1)Lomonosov Moscow State University, Faculty of Physics, Russia (2)Institute of Applied Physics RAS, Russia (3)Lobachevsky State University of Nizhny Novgorod, Russia (4)Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University, Russia (5)Quantum Technology Centre, Lomonosov Moscow State University, Russia
Resume : Silicon nanoparticles (Si-NPs) have a wide range of applications due to specific optical properties. They have high potential for use in biophotonics owing to their high biocompatibility and biodegradability. In this work we present a novel two-stage technique of Si-NPs fabrication. At the first stage silicon nanowires (Si-NWs) are fabricated by the metal-assisted chemical etching of low- and high boron-doped crystalline silicon wafers. At the second stage the Si-NPs are produced by picosecond laser ablation of the Si-NWs in distilled water and ethanol. The outcome of the technique are suspensions of chemically pure Si-NPs. An advantage of the technique is that the ablation threshold for the Si-NWs is significantly lower than that for crystalline silicon, which allows obtaining a larger number of Si-NPs at lower energy costs. Analysis of structural properties revealed that the typical size of the Si-NPs is in the range of 10–90 nm for ablation both in water and ethanol with the maximum of the size distributions in the range of 15–40 nm. Fluorescence and spectrophotometry studies show that the fabricated Si-NPs exhibit fluorescence with emission peaks in the red visible range and show effective light scattering, respectively. Thus, the studied Si-NPs are promising as contrasting agents for visualization of living organisms in both fluorescence imaging techniques and optical coherence tomography. The study was supported by the Russian Science Foundation, project no. 19-12-00192.
Authors : Tomas Tamulevicius (1 2)*, Jaunius Mykolaitis (1), Mindaugas Juodenas (1), Asta Tamuleviciene (1 2), Algirdas Lazauskas (1), Sigitas Tamulevicius (1 2)
Affiliations : (1) Kaunas University of Technology, Institute of Materials Science, K Barsausko St. 59, Kaunas LT-51423, Lithuania; (2) Kaunas University of Technology, Physics Department, Studentu St. 50, Kaunas LT-51368, Lithuania, * email@example.com
Resume : Metal nanoparticles (NPs) have been attracting a lot of attention recently due to their size and shape dependant optical properties. Collective free electron oscillations driven by an external electromagnetic field in the confined space of a NP results in a so-called localized surface plasmon resonance featuring sharp extinction peaks in the optical spectra. Historically most metal NPs were synthesized chemically but with the advent of ultra-short pulse lasers new pathways of synthesis and post-processing of monodisperse NPs have emerged. One of the main advantages of NPs synthesized by laser ablation in contrast to chemical synthesis routes is that the resulting NPs can be made ligand-free. The exclusion of residual contamination is important for a myriad of bio applications. Many laser parameters influence the yield and size distribution of the NPs because they are directly related to complex temporal evolution of physical-chemical phenomena that take place during the laser ablation of a submerged metal target. In this work, the fundamental harmonic (1030 nm) of a linearly polarized Yb:KGW femtosecond laser beam was utilized for ablation of pure Ag, Au and Cu targets in ultrapure Type 1 water. The dependences of the resulting nanoparticles’ optical properties and size distributions on the laser processing conditions, namely pulse energy and pulse density, were investigated and the conditions ensuring the highest NP generation yield were highlighted.
Authors : Y. Mansour, Y. Battie, A. En Naciri, A. Koch, N. Chaoui LCP-A2MC, Université de Lorraine, 1 bd Arago, 57070 Metz S. Champmartin LAMPA, ENSAM d’Angers, 2, Bd du Ronceray, BP 93525, 49035 Angers, France
Affiliations : LCP-A2MC, Université de Lorraine, 1 bd Arago, 57070 Metz
Resume : By irradiating a cylindrical gold target rotated at a high-speed within the range 90–3000 rpm in pure water, we prepare spherical and ligand-free Au nanoparticles (NPs) with a size < 5 nm, as measured by transmission electron microscopy (TEM), which are likely to be primary NPs. Usually, the generation of NPs showing such a small size requires either a laser post-treatment1 and/or chemical additives. As the rotation rate of the target is increased, calculated 3D flow patterns revealed different hydrodynamic regimes, which clearly influence the ablation rate of the process as well as the colloidal properties. The ablation rate has been determined as a function ablation duration by in situ monitoring the extinction spectra of the Au colloidal solution and by modeling the extinction spectra using theoretical calculations based on shape distributed effective medium theory (SDEMT)2. In addition to confirm the importance of fluid dynamics in pulsed-laser ablations in liquids, this study provides a way for producing in one step pure Au NPs with sizes <5 nm which are suitable for applications in catalysis. Keywords: laser ablation, colloids, nanoparticles, gold, optical properties.  MANSOUR Y., BATTIE Y., EN NACIRI A., CHAOUI N, Mechanisms and advanced photothermal modelling of laser-induced shape transformations of colloidal gold nanorods by nanosecond laser pulses, Nanoscale 11, 11679 - 11686 (2019)  RESANO-GARCIA A., BATTIE Y., EN NACIRI A., AKIL S., CHAOUI N, Experimental and theoretical determination of the plasmonic responses and shape distribution of colloidal metallic nanoparticles, Journal of Chemical Physics 142, 134108, (2015)
Authors : Javier Prada(1,2), René I. Rodríguez-Beltrán(1,2,3), Sandra Paszkiewicz(4), Anna Szymczyk(4), Tiberio A. Ezquerra(5), Pablo Moreno(1), Esther Rebollar(2).
Affiliations : 1Grupo de Aplicaciones del Láser y Fotónica (ALF-USAL), Universidad de Salamanca, Pl. de la Merced s/n, 37008 Salamanca, Spain; 2Instituto de Química Física Rocasolano (IQFR-CSIC), C/Serrano 119, 28006 Madrid, Spain; 3CONACyT – Unidad Monterrey, Centro de Investigación Científica y de Educación Superior de Ensenada (CICESE), Alianza Centro 504, PIIT, CP 66629 Apodaca, México; 4West Pomeranian University of Technology, Piastow Av. 19, PL-70310 Szczecin, Poland; 5Instituto de Estructura de la Materia (IEM-CSIC), C/Serrano 121, 28006 Madrid, Spain.
Resume : We present a study on the formation of Laser Induced Periodic Surface Structures (LIPSS), with linearly polarized femtosecond UV laser pulses (265nm), on the surface of free-standing films of Poly(ethylene terephthalate) (PTT) and PTT reinforced with tungsten disulfide nanotubes (PTTWS2) and their effect on the chemical and mechanical properties of both materials. We report the changes in the surface topography, wettability and surface energy, Young Modulus and adhesion force, by means of Atomic Force Microscopy, contact angle and Peak-Force Quantitative Nanomapping measurements, respectively. LIPSS were formed at 15.9-31.3mJ/cm2 for PTT, and at 19.1-33.9mJ/cm2 for PTTWS2 for 500 to 10000 pulses. We attribute the higher fluence needed for their formation in PTT-WS2 to either an increase in crystallinity or a decrease in the absorption of ultrashort pulses. LIPSS formed parallel to the laser polarization with a period close to the wavelength of the laser. The effect of nanostructuring was similar in both materials: the original samples were hydrophilic, which increased after irradiation; little change was found in their total surface energy, but their negative polar component increased radically; and LIPSS formation did not affect the Young Modulus, although a decrease by a factor of four was found for the adhesion force. We conclude that the origin of this behavior as well as the increase of negative polar surface energy is a change of surface chemistry during irradiation.
Authors : Yaroslava Andreeva, Nipun Sharma, Francis Vocanson , Yaya Lefkir, Nathalie Destouches, Anton Rudenko and Tatiana Itina
Affiliations : Yaroslava Andreeva ITMO University, Saint Petersburg 197101, Russia; Nipun Sharma Univ. Lyon, Laboratoire Hubert Curien, UMR CNRS 5516/UJM-Saint-Etienne, Saint-Etienne 42000, France; Francis Vocanson Univ. Lyon, Laboratoire Hubert Curien, UMR CNRS 5516/UJM-Saint-Etienne, Saint-Etienne 42000, France; Yaya Lefkir Univ. Lyon, Laboratoire Hubert Curien, UMR CNRS 5516/UJM-Saint-Etienne, Saint-Etienne 42000, France; Nathalie Destouches Univ. Lyon, Laboratoire Hubert Curien, UMR CNRS 5516/UJM-Saint-Etienne, Saint-Etienne 42000, France; Anton Rudenko The University of Arizona, USA; Tatiana Itina Univ. Lyon, Laboratoire Hubert Curien, UMR CNRS 5516/UJM-Saint-Etienne, Saint-Etienne 42000, France.
Resume : Nanocomposite materials composed of plasmonic nanoparticles (NPs) inside semiconductor transparent thin films have recently attracted attention due to their unique physical and chemical properties. Particular interest represents laser-assisted fabrication and treatment of such materials, e.g. laser-induced self-organization of nanoparticles, structural modifications of the porous film, laser nanostructuring, etc. Here we demonstrate experimental and numerical results on the laser-assisted fabrication of plasmonic-semiconductor nanocomposites based on TiO2 thin films containing Ag and Au nanoparticles. The dependencies of the optical properties of such nanocomposites on laser irradiation parameters and on the metallic fractions are examined. The main mechanisms of Au and Ag nanoparticles formation in semiconductor thin film under UV laser irradiation, nanoparticle size distribution, composition and location are revealed and discussed based on the developed modeling. The obtained results pave the way for the application of laser techniques for a better-controlled fabrication of plasmonic-based thin films. The obtained nanocomposites can be used in novel nanophotonic devices for sensing, light field control as well as photocatalysis, photovoltaic, nonlinear optics and etc.
Fundamentals of laser-materials interactions I : Peter SCHAAF
Authors : Lienau, Christoph* (1), Zhong, J.H. (1), Yi, J. (1), Wang, D. (2)
Affiliations : (1) Institute of Physics, Carl von Ossietzky University, 26111 Oldenburg, Germany (2) Institut für Mikro- und Nanotechnologien MacroNano, Technische Universität Ilmenau, 98693 Ilmenau, Germany
Resume : The integration of metallic plasmonic nanoantennas with quantum emitters (QE) fundamentally alters their optical nonlinearities. Such hybrid nanosystems promise a plethora of novel applications, from ultrafast all-optical switching to random nanolasing and enhanced harmonic generation. Here, we explore a new platform for implementing these functionalities: percolated individual Au nano-sponges, fabricated by solid-state dewetting of silver/gold bilayers. We show that such sponges support hot spots that are localized on a 10 nm scale with long plasmonic lifetimes and exceptionally high Purcell factors . Their large field enhancements make them appealing as efficient photoemitters  and for plasmon-emitter coupling since different types of QE can be infiltrated into the nanopores without the need for lithography methods . We study the dynamics of this plasmon-QE coupling by probing time-resolved interferometric nonlinear emission from individual porous gold nanosponges infiltrated with zinc oxide QE. We demonstrate boosting of second harmonic and uncover the quantum pathways nonlinear QE-plasmon coupling. Our results offer new opportunities for enhancing and coherently controlling optical nonlinearities in hybrid nanoantennas.  J. H. Zhong et al., Nano Lett. 18, 4957 (2018)  G. Hergert et al., Nature Light 6, e17075 (2017)  J. M. Yi et al., ACS Photon. 6, 2779 (2019)  J. H. Zhong et al., Nature Comm., in press (2020)
Authors : Wei-Yang Tien , Yu-Sheng Huang , Lih-Juann Chena *
Affiliations : Department of Material Science and Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan
Resume : Laser in nanoscale has been found to be a useful device in nano-science and nano-technology. Compared with conventional laser, it transmits signal in a faster and more efficient way. In the present study, we demonstrate SPP nanolaser consisting of ZnO nanowires coupled with single-crystalline aluminum film and high dielectric interlayer. High quality ZnO nanowires synthesized by vapor-liquid-solid mechanism acted as gain media to operate lasing at room temperature. Single-crystalline aluminum film grown with molecular beam epitaxy is critical to decrease plasmonic losses. High dielectric layer (HfO2, ZrO2, TiO2) deposited by atomic layer deposition (ALD) was inserted between ZnO nanowires and Al film. The thresholds for lasing were measured to be considerably lower with the addition of dielectric layer. Such suppression is attributed to dielectric layer mediating strong confinement of optical field in the subwavelength regime. Dielectric constant was found to play an important role for laser performance.
Authors : Marcel Himmerlich 1, Pierre Lorenz 2, Martin Ehrhardt 2, Karolina Bogdanowicz 1, Mauro Taborelli 1, Klaus Zimmer 2
Affiliations : 1 CERN, European Organization for Nuclear Research, 1211 Geneva 23, Switzerland; 2 Leibniz Institute of Surface Engineering (IOM), Permoserstraße 15, 04318 Leipzig, Germany;
Resume : Laser irradiation of metals can result in nanostructured surfaces, which exhibit special functionality like low reflectivity or reduction of the escape probability of secondary electrons. The surface modification process can be engineered for dedicated applications. Laser-induced secondary electron yield (SEY) reduction of copper was already mainly reported for processing with 532 nm ps-lasers. In this study, the laser treatment of OFE copper surfaces is investigated by applying ps-laser irradiation in air (pulse duration 12 ps, repetition rate 100 kHz) with different wavelengths (355, 532 and 1064 nm) at room temperature. The aim of the treatment is the fabrication of a large-area nanostructured copper surface with reduced SEY. The influence of the most relevant treatment parameters laser power, line distance and scanning speed on the thickness of material modifications, the ablation depth, the degree of copper surface oxidation and the surface topography is analysed. Similar surface structures and material characteristics are observed for all investigated laser wavelengths. The SEY can be reduced from above 2 to 0.7. These low SEY values are achieved for a wide range of applied power density at given wavelength, especially for 355 nm and 1064 nm. Laser treatment using 532 nm is more challenging due to a higher sensitivity of the SEY to changes of laser power and scanning velocity. Consequently, the utilization of 1064 nm is technologically promising.
Authors : A. Cubero 1, E. Martínez 1, L.A. Angurel 1, G.F. de la Fuente 1, R. Navarro 1, H. Legall 2, J. Krüger 2, J. Bonse 2
Affiliations : 1 - ICMA (Instituto de Ciencia de Materiales de Aragón, CSIC-Universidad de Zaragoza), Zaragoza, Spain ; 2 - Bundesanstalt für Materialforschung und –prüfung (BAM), Berlin, Germany.
Resume : Niobium metal is the pure element with the highest superconducting critical temperature (Tc= 9.2 K), which is present in many applications. Particularly, in superconducting radio frequency (SRF) cavities of particle accelerators, the control of the surface characteristics of pure Nb is crucial, as the presence of defects may generate magnetic flux pinning that can increase by more than two orders of magnitude the surface critical current, ic. Several procedures such as chemical- or electro-polishing have been used aiming at cleaning surface contamination and decreasing its roughness. Sub-nanosecond lasers can be applied to generate a broad range of micro and nanostructures (e.g. Laser-Induced Periodic Surface Structures, LIPSS) that strongly modify the materials properties - as wettability, color, oxidation resistance or antibacterial behavior. In this work, we analyze a variety of surface structures generated on pure Nb sheets with two laser systems (300 ps UV, 30 fs n-IR) by exploring a range of processing parameters, which include pulse overlap, irradiance or the effective number of pulses, under different atmospheres (air, N2, Ar, vacuum). The effects on Tc, critical currents and critical fields (Bc1, Bc2 and Bc3) have been obtained from magnetization, ac susceptibility and heat capacity measurements, revealing their dependence with the different surface nanostructures and the chemical changes generated with these laser treatments.
Authors : Theo Pflug, Markus Olbrich, Philip Lungwitz, Alexander Horn
Affiliations : Laserinstitut Hochschule Mittweida, Germany; Laserinstitut Hochschule Mittweida, Germany; Laserinstitut Hochschule Mittweida, Germany; Laserinstitut Hochschule Mittweida, Germany
Resume : This work provides insights into the excitation of the vibrational modes and subsequent ablation of organic materials induced by mid-IR laser radiation. However, when using ultrafast laser radiation, a nonlinear excitation of the electron system occurs in addition to the resonant excitation of the molecular vibrations. Therefore, this work compares the ablation of PMMA after nonlinear electronic and linear vibrational excitation and investigates the dynamics during and after excitation by pump-probe imaging ellipsometry. At pulse durations in the femtosecond range, the strong electrical field excites electrons by tunnel ionization, causing an increase of the extinction coefficient 𝑘 and ablation independent of the wavelength. By increasing the pulse duration up to a few picoseconds, the number of excited charge carriers generated by nonlinear electronic excitation is reduced, so that only at the resonance frequency of the C-H oscillation at 3.4 µm ablation occurs and no change in the extinction coefficient is detectable at all wavelengths. Numerical simulations of the temperature increment and the density of the induced excited electrons support the experimental results qualitatively. Both the experimental results and the simulations demonstrate that the ablation threshold for linear excitation is lower than for non-linear excitation.
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Fundamentals of laser-mater interactions II : Razvan STOIAN
Authors : Anna Haider, Michael Bayer, Christoph Ahamer, Stefan Trautner, Johannes D. Pedarnig
Affiliations : Institute of Applied Physics, Johannes Kepler University, A-4040 Linz, Austria
Resume : We present femtosecond laser-induced breakdown spectroscopy (fs-LIBS) methods for element detection with high spatial resolution and subsequent digital reconstruction of chemical images. Fs-lasers produce well defined ablation craters due to limited heat transfer out of the laser-matter interaction volume which is beneficial for high resolution LIBS imaging. Measurements were conducted using a fs-laser that is capable of producing 400 fs pulses at a wavelength of 1040 nm. Laser pulses at the fundamental or the second harmonic wavelength were focused on the sample by means of glass lenses or Schwarzschild microscope objective for plasma excitation. Samples were placed on a 2D translation stage and each site at the sample surface was measured by one laser pulse. Plasma radiation was detected in backwards direction. LIBS experiments were conducted on different samples: (a) commercial Cu grids (150 µm and 30 µm mesh) on Mn metal substrate, (b) Cu microdot arrays (dot size: e.g. 8 µm x 8 µm, thickness 60-300 nm) on Si wafer substrates produced by nanoimprint lithography, and (c) Cu thin films (thickness 35-500 nm) evaporated onto glass slides. Our results show accurate digital sample reconstruction from measured LIBS signals for the Cu grid and microdot samples. On the Cu thin films the ablated mass per single fs-pulse was around 10 fg which is equivalent to a Cu particle of radius 640 nm. Imaging experiments with another fs-laser (175 fs, 400 nm) produced similar results and individual Cu microdots of mass approx. 35 fg and equivalent particle radius 970 nm were detected. Our next LIBS measurements will be conducted using double-pulse fs laser excitation for even higher spatial resolution and lower sampled mass. Financial support by the Austrian Research Promotion Agency FFG is gratefully acknowledged (K-project PSSP 871974). We acknowledge M. Haslinger and Profactor GmbH for the preparation of Cu/Si samples.
Authors : Morris J.J. Weimerskirch, Fabian Kraft, Tristan O. Nagy
Affiliations : University of Vienna, Physics of Nanostructured Materials; University of Vienna, Physics of Nanostructured Materials; University of Vienna, Physical Chemistry
Resume : In LIBS, a laser pulse ignites a plasma at the surface of a sample, which is then spectroscopically analysed. In LIBS-Stratigraphy, this procedure is repeated, subsequent pulses ablate layer after layer, penetrating the sample. One of the challenges in LIBS-Stratigraphy has been the recovery of the crater depth. A common approach is to assume a material dependent average ablation rate. However, due to complex light-matter, light-plasma interaction, fluctuations among the laser pulses and incubation effects, the ablation rate varies wildly throughout one LIBS experiment and it has been shown that this measure is neither linear, nor does it solely depend on the material composition. Optical Coherence Tomography (OCT) is a well established imaging technique wherein a low-coherence light source is used in an interferometer to gain depth information of a sample. Typically, a narrow beam is scanned over the surface capturing three dimensional features of a sample, which have been used to analyse LIBS craters *ex-situ*. We present an approach to measure the crater depth and shape *in-situ* and online without any moving parts, yielding a dynamic history of the crater formation. This gives us access to interesting parameters, such as the true ablation rate and thus a mapping of the LIBS spectra to their true depth. Possible use cases range from fundamentals such as the study of incubation effects to applications such as the recovery of mass density using only optical tools.
Authors : Morris J.J. Weimerskirch, Fabian Kraft, Ulrich Pacher, Tristan O. Nagy
Affiliations : University of Vienna, Physics of Nanostructured Materials; University of Vienna, Physics of Nanostructured Materials; University of Vienna, Physical Chemistry; University of Vienna, Physical Chemistry
Resume : Additive manufactured (AM) materials with gradually changing composition, so-called Nabla-materials, promise a revolution in industrial applications. The materials' properties such as flexibility, abrasiveness or density can be varied in the same part. One method to prepare functionally-graded additively manufactured materials (FGAM) is direct metal deposition as (a mixture of) metal powder injected into a gas jet and coaxially directed onto a cw-laser generated meltpool at the workpiece’s surface. By functionally grading the chemical composition and hence the physical properties of a workpiece, AM enables unprecedented opportunities in automotive, aerospace and medical applications, where engineers direct their close attention to a high standard combination of quality assurance and quality control (QA/QC) . Laser-induced breakdown spectroscopy (LIBS) is a fast and cheap method to do elemental analysis, as it requires no sample preparation and only optical access to the parts during the graded manufacturing process . For additively manufactured goods, LIBS as a fast, sensitive and micro-invasive method does not interfere with the laser-based AM process and represents the only method to access chemical information of the solidified solder after each addition in real time . This information is neither accessible after the completed AM process, nore via slow and insensitive x-ray spectroscopic methods during the AM buildup. We present our latest results using LIBS on AM-parts.  https://doi.org/10.1016/j.addma.2018.06.023  https://doi.org/10.1364/OE.27.004612  https://doi.org/10.1016/j.addma.2018.10.043
Authors : Jyotsna Dutta Majumdar1 and Andreas Weisheit2
Affiliations : 1Department of Metallurgical and Materials Engineering, Indian Institute of Technology Kharagpur, India, e-mail: firstname.lastname@example.org 2Fraunhofer-Institut für Lasertechnik ILT, Steinbachstraße 15, D-52074 Aachen, Germany, e-mail: email@example.com
Resume : Direct laser cladding refers to development of component by melting the material in the form of powder or wire and subsequently, deposition of the molten materials on a dummy substrate in a layer by layer fashion to achieve the near net shape using computer aided designing. The process may be applied to develop metals/alloys, metal matrix composite and intermetallics. In the present contribution, titanium aluminide (with the composition of Ti45Al5Nb0.5Si) based composite has been developed by direct laser cladding, where, TiC has been added as dispersoids in molten TiAl. Direct laser cladding has been conducted using a high power (3 kW) fiber optic delivered Nd:YAG laser (with a beam diameter of 2 mm) using a 3-axis handling system in a layer by layer fashion to on Ti-6Al-4V substrate to develop a coupon with a dimension of 10 mm x 10 mm x 5 mm using an applied power of 500 W, scan speed of 300 mm/min and powder feed rate of 2.2 g//min and 10 wt.%TiC addition. Addition of TiC leads to formation of defect free microstructures under varied parameters, except a few processing conditions. There is formation of complex carbides (Ti2AlC, Ti3AlC2 and Ti2AlC) in addition to TiC phase in the microstructure of duplex 2+ phase. There is improvement in microhardness due to TiC addition from 490 VHN to 525 VHN. The wear and high temperature oxidation resistance properties have been discussed in detail.
Authors : A. Guarnaccio (1), C. Belviso (2), L. Lettino (2), F. Cavalcante (2), S. Orlando (1)
Affiliations : (1) CNR – ISM, Sede di Tito Scalo, Zona Industriale di Tito Scalo; 85050 (PZ), Italy; (2) CNR – IMAA, Zona Industriale di Tito Scalo; 85050 (PZ), Italy
Resume : Growing interest in preparation of thin films and zeolite nanocrystals useful for optical and electronic devices , catalytic membranes  and chemical sensors  has been developed in the recent years. This interest is connected with advantages like chemical and thermal stability together with zeolite nanoparticles’ properties related to their potential size, shape and magnetic selectivity. Despite some different methods exist for zeolite films preparation, the Pulsed Laser Ablation (PLA) is one promising method because of advantages like applicability to any zeolite structure which is important for synthetic materials, films thickness and crystal structure control, among others. The here presented study refers to some synthesized magnetic zeolite target materials treated by PLA under different laser power densities and enviromental conditions like vacuum, air and/or applied magnetic field during laser ablation process. The aim is to investigate the fs pulsed laser effects on zeolite crystal structure and morphology of the resulting deposits and target surfaces in order to find the best set-up conditions giving the required fragmentation and/or preferential orientations of the resulting ablated material. These characteristics are of fundamental importance not only for the study of PLA process on zeolites but also for the evaluation of the resulting zeolite nanocrystals possible applications. For this purpose, both laser-irradiated deposits and targets have been characterized by Scanning Electron Microscopy (SEM) and X-Ray Diffraction analysis (XRD). Morphological results indicated that, depending on zeolite structure and ablation conditions, amorphization, orientation and/or changes in nanoparticle zeolite size took place after the laser irradiation.  Herron N. (1995) Zeolites as Hosts for Novel Optical and Electronic Materials. In: Herron N., Corbin D.R. (eds) Inclusion Chemistry with Zeolites: Nanoscale Materials by Design. Topics in Inclusion Science, vol 6. Springer, Dordrecht  R. Dragomirova and S. Wohlrab, Zeolite Membranes in Catalysis—From Separate Units to Particle Coatings, Catalysts 2015, 5, 2161-2222.  X. Xu, J. Wang, and Y. Long, Zeolite-based Materials for Gas Sensors, Sensors 2006, 6, 1751-1764.
Authors : M. Fernández-Arias 1, M. Boutinguiza 1, J. del Val 1, A. Riveiro 1, D. Rodríguez 2, F.J. Gil 3, J. Pou 1
Affiliations : 1 Applied Physics Department, University of Vigo, Vigo, Spain; 2 Biomaterials, Biomechanics and Tissue Engineering Group, Materials Science and Metallurgical Engineering Dept., UPC-Barcelona TECH, Barcelona, Spain; 3 School of Dentistry. Universitat Internacional de Catalunya, Barcelona, Spain
Resume : For a long time antibiotics have been used to kill efficiently bacteria and limit infections proliferation. However, it is well known that pathogens develop resistance to antibiotics over time, which poses a serious threat to human health. The use of metallic and metal oxide nanoparticles as antibacterial agent is been highly studied as alternative. In particular, copper nanoparticles present broad-spectrum bactericidal properties and are prepared from earth-abundant material and inexpensive. In this work Cu foils were ablated in air and Ar atmospheres using a nanosecond Nd:YVO4 laser operating at 532 nm and a picosecond laser Nd:YVO4 operating at 1064 nm to produce and deposit Cu nanoparticles on Ti substrates. The size, composition and crystallinity of the synthesized nanoparticles were characterized by field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), X-ray diffraction (XRD) and UV-vis spectroscopy. The Cu nanoparticles ion release was also estimated by inductively coupled plasma optical emission spectrometry (ICP-OES), while the antibacterial activity of the samples was tested against Staphylococcus aureus. The obtained coatings consisted of interconnected nanoparticles of copper and copper oxide nanoparticles. The use of Ar contributed to reduce the oxidation degree of the synthesized nanoparticles. The samples of copper and copper oxide nanoparticles deposited on Ti exhibited inhibitory effect on Staphylococcus aureus.
Laser processing of materials II : Florence GARRELIE
Authors : F. Andrei (1), M. Dragoman (2), M. Filipescu (1), N. D. Scarisoreanu (1), A. Moldovan (1), F. Craciun (3), I. Boierasu (1), V.S. Teodorescu (4), Maria Dinescu (1)
Affiliations : (1) INFLPR - National Institute for Laser, Plasma and Radiation Physics, Bd. Atomistilor 409, RO-77125 Magurele, Romania; (2) IMT - National Institute for Research and Development in Microtechnologies, Str. Erou Iancu Nicolae 126 A, RO-077190 Voluntari, Romania; (3) CNR - Istituto di Struttura della Materia, Area della Ricerca di Roma - Tor Vergata, Via del Fosso del Cavaliere 100, IT-00133 Rome, Italy; (4) INFM - National Institute of Material Physics, Bd. Atomistilor 405 A, RO-77125 Magurele, Romania
Resume : Ferroelectric thin films have been intensively investigated in the last decades, owing to a combination of dielectric, electric and electromechanical properties with a wide spectrum of applications. It was recently shown that graphene-ferroelectric heterostructures can be successfully used in improving the functionalities of graphene-based transistors/devices. The qualities of the ferroelectric surface and of the growth/transfer process of graphene on it are key issues for obtaining nanoelectronic devices with enhanced properties and functionalities. Lead Zirconate Titanate (PZT) and HfO2 have been chosen as ferroelectric materials. A parametric study regarding the deposition of very thin layers (thicknesses in the nm range) directly on Silicon substrate, with very low roughness and appropriate ferroelectric properties was carried out. Another parametric study is related to properties modification by strain engineering for Y-doped BiFeO3 (Bi0.97Y0.03FeO3) films grown on Nb:SrTiO3(001) substrates. The layers photocatalytic activity was shown to strongly depend of epitaxial strain relaxation due to thickness variation.
Authors : Nicolas GLANDUT(1), Nicolas RANGER(1), Haimin DING(1,2), Romain LUCAS(1), Alexandre BOULLE(1), Catalin CONSTANTINESCU(1)
Affiliations : (1) IRCER (UMR 7315) - CNRS / University of Limoges, F-87068 Limoges, France; (2) School of Energy, Power and Mechanical Engineering, North China Electric Power University, Baoding 071003, PR China
Resume : Titanium carbide, TiC, is a non-oxide ceramic exhibiting faced-centred cubic (fcc) crystal structure, a high melting point of around 3 000 °C, and an exceptional hardness of ca. 28 GPa. Electrochemical behaviour, especially vis-à-vis of hydrogen absorption and storage, has already been thoroughly studied, and it has been demonstrated that it changes with the amount of carbon vacancies. In this context, the aim of this study is to compare the electrochemical properties of stoichiometric and substoichiometric titanium carbides, with respect to their substrate type and crystallographic orientation. Thus, thin films are synthetized on various substrates, i.e. MgO (111) and Al2O3 (0001), by pulsed laser deposition (PLD). First, their morphology and structure are investigated by atomic force microscopy (AFM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and high resolution X-ray diffraction (HR-XRD). The films are of high quality on all tested substrates, and no delamination is observed. Subnanometric roughness and hetero-epitaxial growth is observed on MgO substrates, following the (111) atomic planes. On c-cut sapphire substrates, TiC films are also preferentially orientated following the (111) plans, yet a phase change seems to be observed, linked to a possible carbon expulsion from the chemical structure. Finally, electrochemical investigations are also performed, and results are corroborated with respect to the structure.
Authors : Niemczyk, A.(1), Franklin, S.E.(2), & Baranowska, J.*(1).
Affiliations : (1) West Pomeranian University of Technology, Szczecin, Faculty of Mechanical Engineering and Mechatronics, Department of Materials Technology; al. Piastów 19; 70-310 Szczecin, Poland; (2) Advanced Research Center for NanoLithography (ARCNL), Contact Dynamics group, Science Park 106, 1098 XG Amsterdam, The Netherlands
Resume : Although DLC films are already well known and applied widely in industry, they are still constantly being developed and improved through the intensive advancement of vacuum deposition techniques. For example, DLC-silver nanocomposite films, which show favourable friction behavior, biocompatibility and antimicrobial activity, have been produced using different techniques including the thermionic vacuum arc method, PE- and RF PA-CVD. However, for such DLC/Ag composite coatings it would be preferable if the deposition method allowed the amount, size and distribution of the silver particles to be controlled more readily. The aim of our work was to produce DLC/Ag nanocomposite thin films using a simple and convenient pulsed laser deposition technique and define the influence of process parameters on the silver particle formation and film properties. Graphite and silver targets were ablated using a KrF laser in vacuum or nitrogen/argon atmosphere. The structure of the deposited DLC/Ag films was studied by Raman spectroscopy and XRD techniques. The quality of the films, in terms of microcracks, roughness, and silver particle size and distribution, was evaluated by SEM, STEM and AFM methods. The friction behaviour was also investigated. The results clearly indicate that PLD is well-suited to obtain a uniform distribution of silver particles, the size of which can be controlled by the type of assisted gas used during the deposition process.
Authors : F. Stock1, F. Antoni1, D. Aubel2, S. Hajjar-Garreau2, P. Lévêque1
Affiliations : 1 ICube, D-ESSP, 23 rue du Loess, 67037 Strasbourg - France; 2 IS2M, 15 rue Jean Starcky 68057 Mulhouse - France
Resume : One of the most crucial challenge for optoelectronic and photovoltaic applications is the finding of a viable alternative to the use of transparent conductive oxide (TCO) and more especially to Indium based oxides (like the well-known and largely used Indium Tin Oxide). In recently published studies, we proved the possibility to obtain pure carbon transparent conductive electrodes thanks to an innovative full laser process while keeping high compatibility with standard microelectronic technology. We firstly elaborate Diamond-Like Carbon layers (DLC) by Pulsed Laser Deposition (PLD) of high purity graphite. This PLD grown DLC is a hydrogen and impurity free amorphous carbon composed of a homogenous mixture of sp² (graphitic) and sp3 (diamond) hybridized carbon atoms. It shares a strong kindship with diamond as being a perfect electrical insulator while presenting high transparency in the visible range. We demonstrate that performing UV laser annealing on DLC leads to bring high conductivity on its surface. This major change is explained by the formation of a fully graphitized sp² layer on the top of the DLC. Obtained conductivity and transparency is similar to commercial ITO performances. This technology presents some very innovative perspectives and interests. Annealed DLC layers are already suitable to be used as transparent resistors being able to dissipate high power without altering the layer. We also investigate the direct integration of this technology in an organic light emitting diode (OLED) showing the potential of this technology. We also highlight the biocompatibility of the layers, offering a very large application field to this technology.
Authors : C. Kryou (1), A. Kalaitzis (1), C. Chandrinou (1), M. Orfanou (2), C. Tamvakopoulos (2), I. Zergioti (1)
Affiliations : (1) National Technical University of Athens, Greece; (2) Biomedical Research Foundation Academy of Athens, Greece;
Resume : The use of different 3D printing technologies for pharmaceutical manufacturing provides new opportunities for personalized medicine and on-demand tailored drug products, such as implants and other dosage forms. In this work we present our recent achievements in developing a viable manufacturing process for printed personalized dosage forms onto thin films. Laser Induced Forward Transfer (LIFT) printing technology has been successfully applied by means of a 355 nanosecond laser to deposit active substances starting from solutions in a wide range of viscosities. The main advantage of LIFT printing lies in the preparation of thin films as dosage forms, each with different designs, multiple actives and sizes. In the context of investigating the effectiveness of the LIFT printing, a Mass Spectrometry (MS)-based analytical technique was developed and applied for the study of paclitaxel printed with LIFT on thin potato starch and glass substrates. The active pharmaceutical ingredient (API) quantification of the LIFT-printed dosage forms was confirmed using a High-Performance Liquid Chromatography tandem Mass Spectrometry (HPLC-MS/MS) analysis. The obtained thin films were characterized regarding their recovery, disintegration time and homogeneity. The final aim will be to develop slow release skin patches containing paclitaxel which will be applied transdermally.
Authors : Casanova*, A. (1), Reymond, M. (1), Surendran, H. (1), Delaporte, Ph. (1), Robin, J. (2), Magdinier, F. (2) & Alloncle, A.P. (1).
Affiliations : (1) Aix-Marseille University, CNRS, Laser, Plasma and Photonic Processes, Marseille France (2) Aix-Marseille University, INSERM, Marseille Medical Genetics, France
Resume : Printing techniques applied to biology have begun to develop since the 2000s and undergo a high development. Based on interdisciplinary approaches they use a combination of cells, chemistry, engineering and sophisticated protocols for several applications from tissue engineering or organ creation to regenerative medicine and new drug discovery. We took advantage of our experience on the laser-induced forward transfer (LIFT) technique to print bioinks containing stem cells. This method uses a short laser pulse to transfer tiny amounts of material from a thin film donor to a receptor substrate. Under appropriate conditions, the pulse induces a jet formation, propagating perpendicularly from the donor substrate. The targeted material is then deposited as a droplet on the collector. We present the LIFT process optimization allowing to master the bioink deposition in order to create reliable ordered matrices of bioink micro-droplets containing stem cells with a high spatial resolution. The study of jet dynamics using real-time visualizations was carried out and highlighted the need to control both the environmental conditions of printing and the bioinks rheology. By changing the cell concentration in the film and the laser pulse energy we control the droplet size and the number of cells per droplet (from tens of cells down to single cell). This bioprinting process allows to print several kinds of cells on the same substrate which opens new perspectives for tissue engineering.
Authors : Mihailescu, A.* (1,2), Popescu-Pelin, G. (1), Socol, M. (3), Socol, G. (1)
Affiliations : (1) National Institute for Lasers, Plasma and Radiation Physics, Magurele, Romania; (2) Faculty of Electronics, Telecommunications and Technology of Information, University Politehnica of Bucharest, Bucharest, Romania; (3) National Institute of Materials Physics, Magurele, Romania
Resume : Real-time gas sensing technologies with minimum human intervention and monitoring are becoming a requisite in many industrial activities. However, these technologies rely heavily on the low-power consumption capabilities of the gas sensor and its auxiliary circuitry as well as on the effective mitigation of the cross-sensitivity of the materials interacting with analytes. Thin films based gas sensors and their arrays are known to be miniaturization-friendly and less demanding in terms of power consumption. This report offers insights on how to fabricate very sensitive miniaturized conductometric gas sensing structures with designated use as CH4 detectors. For this purpose, thin films of SnO2 mixed with ZnO, in various weight ratios, were grown by pulsed laser deposition on glass, alumina and oxidized silicon substrates, at various pressures (10Pa to 50Pa), in O2 atmosphere. The structures were comprehensively tested in a designated controlled environment, at different concentrations of CH4, in dry and humid synthetic air, respectively and were found to be highly responsive even to concentrations as low as 1ppm of analyte. Satisfying performances, not only in terms of detection limit but also in terms of response and recovery times were obtained even for operating temperatures of 25⁰C.
Authors : F. Abate, V. Ambrogi, G. Ausanio, V. Califano, P. Cerruti, V. Marturano, G. P. Pepe, L. M. Vicari
Affiliations : F. Abate Department of Chemical, Materials and Production Engineering (DICMAPI), University of Naples “Federico II”, P. le Tecchio, 80, 80125 Napoli, Italy; V. Ambrogi Department of Chemical, Materials and Production Engineering (DICMAPI), University of Naples “Federico II”, P. le Tecchio, 80, 80125 Napoli, Italy; G. Ausanio CNR-SPIN and Department of Physics “E. Pancini”, University of Naples “Federico II”, P. le Tecchio 80, I-80125 Napoli, Italy; V. Califano Istituto Motori-CNR, via G. Marconi 4, Napoli, 80125, Italy; P. Cerruti Institute for Polymers, Composites and Biomaterials (IPCB-CNR), Via Campi Flegrei, 34, 80078 Pozzuoli (NA) Italy; V. Marturano Institute for Polymers, Composites and Biomaterials (IPCB-CNR), Via Campi Flegrei, 34, 80078 Pozzuoli (NA) Italy; G. P. Pepe CNR-SPIN and Department of Physics “E. Pancini”, University of Naples “Federico II”, P. le Tecchio 80, I-80125 Napoli, Italy; L. M. Vicari CNR-SPIN and Department of Physics “E. Pancini”, University of Naples “Federico II”, P. le Tecchio 80, I-80125 Napoli, Italy
Resume : Functional coatings are finding high value applications in numerous technological fields, especially when involving nanocapsules systems for the release of active agents. Traditional deposition methodologies often produce poor quality coatings due to nanoparticle agglomeration, moreover temperature or solvents involved may damage sensitive bio-based polymers. In this scenario, Matrix Assisted Pulsed Laser Evaporation (MAPLE) technology is able to preserve the integrity of polymeric materials while controlling thickness, composition, and uniformity of the coating. The presented work reports on the use of two families of polymeric nanocapsules: azobenzene-based photo-responsive polyamide nanocapsules and biocompatible/biodegradable PLGA nanocapsules loaded with functional substances. The successful deposition of the capsules on various substrates was confirmed by Infrared Spectroscopy, Scanning Electron Microscopy and Atomic Force Microscopy. The active coatings were then tested as delivery platforms for the encapsulated active agents and release behaviour was monitored via UV-vis spectroscopy. Photo-responsive capsules were able to release the cargo material by application of a visible light-source, while sustained release in PLGA-based capsules occurred due to their erosion and biodegradation. Overall, MAPLE technique qualifies as a laser-based technique with potential use also in applications such as food packaging, anticorrosion coatings and biomedical devices.
Authors : Antohe I. (1), Mihăilescu A. (1), Stochioiu A. (1), Jinga I. (1), Popescu-Pelin G. (1) and Socol G. (1).
Affiliations : (1) National Institute for Lasers, Plasma and Radiation Physics - INFLPR, 409 Atomistilor Street, 077125 Bucharest -Magurele, Romania
Resume : Polyaniline (PANi) is an attractive candidate for organic and polymer electronics because of its environmental stability, controllable electrical conductivity and interesting redox properties, offering thus great opportunities for applications in nanoelectronic devices like sensors. The existing methods of obtaining controlled PANi thin films are challenging and request special physical and chemical treatments, both on the substrate surface and for the polymer itself. In this work, matrix assisted pulsed lased evaporation (MAPLE) technique was applied for obtaining the PANi films. In this context, the MAPLE target consisting of aniline dissolved in a solvent is frozen in liquid nitrogen and afterwards is evaporated using a ArF* laser (λ = 193 nm). The influence of the solvent type and of the laser parameters (wavelengths or fluence) on the PANi properties has been also investigated. Next, these films were characterized using X-ray photoelectron spectroscopy (XPS) and scanning electron microscope (SEM), respectively. Furthermore, the obtained PANi film was used as a sensing element within the fabrication of a low-cost conductometric ammonia gas sensor. The detection of ammonia gas has been carried out both, in dry synthetic air as well as in controlled humidity conditions, using an in-house built setup for testing electrical gas sensors. The proposed sensor is highly sensitive for concentrations of ammonia gas below 1ppm and exhibits a prompt, strong and reproducible response.
Poster 1 : Johannes PEDARNIG, Anne Patricia ALLONCLE, Peter SCHAAF et al.
Authors : Tsai-Hsiu Li 1, Huei-Sen Wang *1, Jia-Hong Pan1 , Hou-Guang Chen 1, Jia-Wei Chen 1
Affiliations : 1. Department of Materials Science and Engineering, I-Shou University, Taiwan, R.O.C.;
Resume : In this study, Zr-Cu-Ni-Al (Zr53Cu30Ni8Al8) and Zr-Cu-Ag-Al (Zr53Cu30Ag8Al8) bulk metallic glasses (BMGs) with or without Si additions were produced and laser welded. To provide rapid welding thermal cycles for the BMG welds, the Nd: YAG laser process with preselected laser parameters was used. After the laser welding process, the microstructure evolution and mechanical properties of the welds were investigated and compared. The results showed that the hardness of the Zr-Cu-Ni-Al or Zr-Cu-Ag-Al BMG alloys increased with the addition of Si. Also, after the laser welding process, although all weld fusion zone (WFZs) in the BMG welds were amorphous (observed by TEM), due to the residual stress caused by the deformation in the WFZs of the BMG welds, higher hardness values were obtained in these zones when compared to those of the BMG parent materials (PMs). For the HAZs in Zr-Cu-Ni-Al BMGs (with or without Si additions) welds, the formation of a Zr/Cu binary crystal phase in these zones became unavoidable, which slightly decreased the hard-ness in these zones. However, the plastic deformation ability of these welds was significantly im-proved after the compression tests. For the Zr-Cu-Ag-Al BMGs (with or without Si additions), no crystalline was found in the heat affected zone (HAZs) of the BMG welds, resulting in a similar magnitude of hardness when compared to those of the PMs. However, when compared to the Zr-Cu-Ni-Al BMG (with or without Si additions) welds, the Zr-Cu-Ag-Al BMG welds showed a brittle fracture nature and worse plastic deformation ability after the compression tests.
Authors : Daniel E. Martinez-Tong [1,2], Mikel Sanz , Esther Rebollar 
Affiliations :  Departamento de Fisica de Materiales. University of the Basque Country (UPV/EHU). 20018, San Sebastian - Spain  Materials Physics Center, CSIC-UPV/EHU. 20018, San Sebastian - Spain  Instituto de Química Física Rocasolano (IQFR-CSIC). C/Serrano 119, 28006, Madrid - Spain
Resume : The formation of laser induced periodic surface structures (LIPSS) on organic surfaces has been one of the key research lines in the laser processing of polymer materials for over the past decade. Besides the investigation about the mechanisms of formation, these nanostructures have shown their potential use in a broad range of applications. However, in most of the so-far published works, LIPSS formation is usually carried out in ambient conditions. To provide further insight into the growth mechanisms of LIPSS and their impact on the physical properties of nanostructured surfaces, we present a work dealing with LIPSS formation under controlled environments. Here, we show the possibility of preparing nanostructured surfaces of poly(ethylene terephalate) (PET) under vacuum, water, alcohols, and oils. We noticed that depending on the surrounding medium, nanostructures with different shapes were formed, not always following the geometrical characteristics of “usual” LIPSS. We have also quantified the physicochemical properties of the irradiated structures by combining macroscopic and nanometric techniques. In the latter case, we made emphasis on the quantification of local properties using Atomic Force Microscopy (AFM). In particular, nanomechanical AFM measurements showed that laser structuring lead to important changes on the mechanical characteristics of the surfaces, reflecting on the Young’s modulus, stiffness, and adhesion force.
Authors : L.N. Dumitrescu1, V. Dinca1, P. Neacsu2, A. Moldovan1, A. Bonciu1,3, V. Marascu1, A. Cimpean2 and M. Dinescu1
Affiliations : 1National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Str., 077125 Bucharest, Magurele, Romania. 2Department of Biochemistry and Molecular Biology, Faculty of Biology, University of Bucharest, Bucharest, Romania. 3University of Bucharest, Faculty of Physics, Bucharest, Romania.
Resume : New advances in biomedicine field have concentrated on producing novel and stable surfaces that can stimulate a specific cellular response toward the demands of implants and medical devices. Among these materials, polyvinylidene fluoride (PVDF) are considered of high interest for biomedical research area due to its a number of characteristics that make it a versatile biomaterial, insolubility, stability in biological media, in vitro and in vivo non-toxicity, or even piezoelectric properties. Nonetheless, the most important disadvantage of PVDF-based biointerfaces is associated to the absence of the functional groups on the fluoropolymer and its hydrophobic character conducting to a deficiency of cell adhesion and proliferation. Within this context, this work aims to investigate the obtaining of PVDF coatings by matrix assisted pulsed laser evaporation (MAPLE) and the in vitro response of MC3T3-E1 pre-osteoblast cells towards the surface microarchitecture. MAPLE deposition parameters and post-deposition thermal treatment were studied for optimizing and designing the morphological features of the coatings, while maintaining the chemical characteristics similar to those of the pristine material. In vitro studies with MC3T3-E1 pre-osteoblasts indicated good biocompatibility, with no significant alteration of the cell adhesion and viability after the thermal treatment of the coatings. The physico-chemical characteristics of the deposited coatings along with favorable in vitro osteoblast response demonstrate that MAPLE is an adequate method for obtaining PVDF coatings for future bio- applications.
Authors : Anjali V Murali(1), Qinfeng Li(1,2), Patricia Alloncle(1), David Grojo(1), Lucie Prokesova(3), Denys Moskal(3), Jiri Martan(3), Philippe Delaporte(1)
Affiliations : (1) Aix-Marseille University, CNRS, LP3 Laboratory, Campus de Luminy, 13009 Marseille, France; (2) Institute of Applied Physics, Abbe Center of Photonics, Friedrich-Schiller-University Jena, Albert-Einstein-Str. 15, 07745 Jena, Germany; (3) University of West Bohemia, Czech Republic
Resume : Improving and increasing the resolution of laser printed structures has become a need to promote new applications in micro/nanotechnologies. To meet the challenges of reproducibility and versatility, we use the Double-Pulse Laser Induced Forward Transfer (DP-LIFT) technique. A long pulse is first applied to melt the film followed by an ultrashort laser pulse synchronized with proper delay to initiate the material transfer in liquid phase towards the receiver substrate. Thanks to DP-LIFT, liquid melt ejections with controllable jet diameters varied from micrometers to nanometers range are achieved. Interestingly, nanodroplets followed by microjets are seen by shadowgraphic imaging and characterized by scanning electron microscope. Numerical simulation of the temperature evolution for copper film suggests that the observation of nanodroplet relies on jet dynamics. The jet dynamics is heavily modulated by various factors like the shape, diameter and the temperature of the pool. The formation of nanojet is assumed to be the result of a combination of a shockwave and an appropriate pool shape. To validate this hypothesis, studies are made on copper films with different thicknesses and varying femtosecond laser spot sizes on target. The experiment yields direct evidence of formation and break-up of thin nanojets. In order to quantitatively understand the influence of shockwave in this process, the experiment is repeated on Ni-Cu layer.
Authors : G. Bulai(1), S. Irimiciuc(2), V. Trandafir(3), F. Husanu(3), S. Gurlui(3)
Affiliations : (1) CERNESIM, Al. I. Cuza University of Iasi, 700506 Iasi, Romania; (2) INFLPR - National Institute for Laser, Plasma and Radiation Physics, , RO-077125, Magurele-Bucharest, Romania; (3) Faculty of Physics, LOA-SL, Al. I. Cuza University of Iasi, 700506 Iasi, Romania
Resume : Cobalt ferrite thin films with interesting structural and magnetic properties can be obtained by pulsed laser deposition. Their characteristics are influenced by the experimental conditions and thus by the plume dynamics. The analysis of the laser induced plasma can help explain the structural and chemical properties of the deposited nano-structured materials and also optimize the deposition process itself. The aim of this study was to obtain information on the dynamics and properties of the expanding plasma generated by laser irradiation (Nd-YAG: 532nm, 10 ns, 10Hz) of stoichiometric and rare earth doped (CoFe2-xRExO4) cobalt ferrite targets. This was done through space- and time-resolved optical emission spectroscopy using an ICCD camera (PI-MAX3) and a monochromator (Acton SP2750). Both the global dynamics of the plasma and the evolution of individual species were analysed. To have an insight on the contribution of each element, plasma plume analysis of pure cobalt and iron targets were performed in the same conditions as the spinel magnetic material. The laser fluence (5 J/cm2) and gas pressure (10-3Torr) were similar to the ones used for the deposition of thin films, while several of the optical emission spectroscopy experiments were done during the actual deposition process. From the space- and time-evolution of several spectral lines, we determined the velocities of the main plasma plume constituents. The excitation temperature distributions were obtained from the Boltzmann plot, in the assumption of local thermodynamic equilibrium. For a more accurate correlation, the same spectral lines analysed for the pure Fe(/Co) plasma were then considered when studying the cobalt ferrite plume.
Authors : Manuel Oliva-Ramirez (a), Andreas Herz (a), Dong Wang (a), Felix Theska (a), Diana Herz (a), Thomas Kups (a), Mária Čaplovičová (b), Mário Kotlár (b), Peter Schaaf (a)
Affiliations : (a) Chair Materials for Electrical Engineering and Electronics, Institute of Materials Science and Engineering and Institute of Micro- and Nanotechnologies MacroNano®, TU-Ilmenau, 98693-Ilmenau, Germany. https://www.tu-ilmenau.de/en/wt-wet/ ; (b) STU Centre for Nanodiagnostics, Slovak University of Technology, Vazovova 5, 812 43 Bratislava, Slovakia
Resume : In the nanoscale, surface dominate over bulk effects leading to a different phenomenology in the behavior of materials. This is quite remarkable in the case of metallic nanoparticles raising a great interest on the field of Nanometallurgy. In particular, supersaturated alloy nanoparticles of two metals that present a solubility gap exhibit an enrich phenomenology and, in principle, their Gibbs free energy determines the kind of decomposition that the system shall undergo. Decomposition mechanisms used as a fabrication method provide a straightforward route to homogeneously distribute the decomposed materials and to boost specific properties of the systems. This allows, among others, to nucleate small precipitates at will or to create multilayers of very thin and controlled thickness. The equilibrium phase diagram, predicts the decomposition mechanism that a supersaturated alloy would undergo. However, variations of this phase diagram are expected in the nanoscale and might be brought to light by analyzing the decomposition of nanoparticles. Herein, the decomposition of AuNi alloy nanoparticles of three different compositions at a temperature close to, but below, the solubility gap contradicts the predictions of the equilibrium phase diagram1 and shows that another factors such as the interface energy, the diffusion of the metals, and the strain energy, play an ultimate role to determine the undergoing decomposition mechanisms. (1) J. Mater. Chem. 2012, 22 (12), 5344.
Authors : C. Cachoncinlle,T. Gibert, E. Millon, A. Caillard, R. Graillot-Vuillecot, A.-L. Thomann, N. Dumuis
Affiliations : GREMI, UMR 7344 CNRS-Université d’Orléans, 45067 Orléans Cedex 2, France
Resume : Wide-gap semiconductors, such as ZnO and GaN, are well known for exhibiting a LASER effect in UV , where their resonant frequencies are located. This LASER radiation is commonly interpreted in the context of the recombination of an electron-hole plasma . However, the exact mechanism behind the amplification at room temperature is not yet clearly established, especially the precise wavelength at which amplification takes place was not predictable. In this work, we hypothesize that the mechanism that drives the sharp amplification on the redwing of the recombination spectrum might be the resonant Rayleigh scattering. Firstly, we present here an ab-initio calculation of the optical gain for these two materials, including renormalization of the gap and filling of the bands. This allows to find the carrier density at laser threshold and set the corresponding resonant frequency. Then, we compare the synthetic spectrum resulting from our computation to those obtained experimentally. We show that the experimental amplification fits with high accuracy the Lorentzian shape of the Rayleigh scattering spectrum. Moreover, the shrinkage of the band-gap explains the red-shifting of the LASER peaks, whereas the maxima of the optical gain are blue-shifted. Furthermore, we demonstrated that the FWHM of the LASER peaks, for GaN and ZnO, are given by the damping coefficient of the resonance of the Drude-Lorentz model.  H. Zhu et al, J. Phys. Appl. Phys. 50 (2017) 045107.  M.A.M. Versteegh et al, Phys. Rev. Lett. 108 (2012) 157402-1.
Authors : N.N. Tarasenka, V.G. Kornev, A.A. Nevar, M.I. Nedel`ko, N.V. Tarasenko
Affiliations : B.I. Stepanov Institute of Physics, National Academy of Sciences of Belarus, 68-2 Nezalezhnasti Ave., 220072 Minsk, Belarus
Resume : The growing interest to SiC nanostructures is based on their exclusive properties that make the SiC material well-suited for uses in heterogeneous catalysis, high power, high temperature electronic devices as well as in biomedicine. In this report the capabilities of laser assisted techniques based on laser ablation and laser induced modification processes for preparation of SiC nanoparticles (NPs) are evaluated. The binary SiC NPs were prepared by ns laser irradiation of the mixture of preliminarily prepared Si and C colloids in ethanol taken in the stoichiometric proportion. The unfocused beam of the second harmonic of Nd:YAG laser (532 nm) with pulse duration of 10 ns, repetition rate 10 Hz and fluences in the range of 230-400 mJ/cm2 was used for laser irradiation. The preparation of SiC compounds was confirmed by the results of the characterization of synthesized particles by the methods of TEM, HRTEM, electron diffraction and XPS. As could be concluded from the TEM and HRTEM images, non-spherical polycrystalline nanoparticles with the mean size about 10 nm were formed in result of co-melting of the initial Si and C NPs. The results of the electron diffraction showed the formation of SiC nanocrystals with a hexagonal internal structure. The synthesized SiC nanocrystals exhibited photoluminescence with a quantum yield of approximately 10% in the visible spectral region that makes them attractive for biomedical applications.
Authors : Athanasios Tiliakos(1), Lavinia Gavrila-Florescu(1), Iuliana Morjan(1), Liana Anicai(2), Adriana Marinoiu(3), Gabriel Prodan(4), Florian Dumitrache(1)
Affiliations : 1: National Institute for Laser, Plasma and Radiation Physics (INFLPR), Romania; 2: Polytechnic University of Bucharest, Romania; 3: National Research and Development Institute for Cryogenic and Isotopic Technologies (ICSI), Romania; 4: Ovidius University of Constanta, Romania
Resume : Pyrolytic nanocarbons (NCs) have been established as materials of choice for catalyst supports and microporous layers in proton-exchange membrane fuel cells (PEM FCs), with R&D efforts focusing on improving yield-to-cost ratios in order to drive down overall manufacturing costs. A critical factor in cost minimization is the amount of noble metal catalyst (traditionally platinum) employed for accelerating the otherwise sluggish ORR and HOR reactions at the FC electrodes. Current successful strategies dictate doping the catalyst supports with co-catalytic trace elements. In our work, we initially target improving on cost-effectiveness by applying laser pyrolytic methods for the synthesis of core-shell NCs of controlled size distribution and morphology. On a second level, we enrich the starting fuel and sensitizer gas mixture (acetylene and ethylene) subjected to the high-power laser irradiation with added diborane and ammonia. The end result is pyrolytic core-shell NCs co-doped with boron and nitrogen co-catalysts, which are further seeded with platinum nanoparticles to serve as catalyst supports for PEM FCs.
Authors : Ageev E.I.1, Grachkova E.Y.1, Larin A.O.1, Yaroshenko V.V.1, Zuev D.A.1
Affiliations : 1 ITMO University, 49 Kronverksky Ave., 197101, St. Petersburg, Russia
Resume : The creation of effective nanoscale sources of broadband (white) radiation, operating in the visible range, is an essential task for the development of active elements of nanophotonics, ultra-compact optical chips, and the study of biological objects. Metal-dielectric nanostructures, combining the plasmon and dielectric components, provide a high degree of localization of electromagnetic energy (plasmon component) and low optical losses (dielectric component), as well as strong nonlinear optical properties. Here we study ultrathin gold films at silicon films or bulk after exposure by femtosecond laser pulses resulted in the integration of metal and high-index semiconductor components. Obtained structures demonstrate a broadband response under excitation with femtosecond pulses at 1050 nm as well as a strong second harmonic generation.
Authors : Fabian Kraft, Morris J.J. Weimerskirch, Tristan O. Nagy
Affiliations : University of Vienna, Physics of Nanostructured Materials; University of Vienna, Physics of Nanostructured Materials; University of Vienna, Physical Chemistry
Resume : In stratigraphic LIBS analysis, the objective is to follow the change of elemental composition along the incident laser beam. However, due to complex light-matter, light-plasma interaction, fluctuations among the laser pulses and incubation effects, the ablation rate typically varies wildly throughout one LIBS experiment. In this work we present a proof of concept to use a coaxially mounted non-scanning single-spot (NoSc-SiSp) optical coherence tomography (OCT) for in-situ absolute depth measurements between the LIBS laser pulses. Unlike standard OCT, we do not use a very narrow, needle-like OCT-beam to scan over the surface of a sample. Instead, a wide OCT-beam is used, losing all the lateral information. This enables us to use OCT coaxially with the LIBS ablation path, passing the same optics and obtain information about the surface and the LIBS crater at the same time.
Authors : K. Potapova*, M. Zykova*, E. Gavrishchuk**, D. Savin**, R. Avetisov*, I. Avetissov*
Affiliations : *D. Mendeleev University of Chemical Technology of Russia **G.G. Devyatykh Institute of Chemistry of High-Purity Substances RAS
Resume : The intrinsic nanoscale point defects generating in the crystal lattice of ZnSe during the crystal growth and doping processes strongly determine the functional properties of the material as well as dopants (Fe, Cr) solubility. Nonstoichiometry and IR luminescence spectra of ZnS:Cr:Fe ZnSe:Cr:Fe powdered preparations and CVD-grown ZnSe:Fe:Cr crystals treated by high-temperature gas-static pressing (HIP) were changing depending on Fe and Cr doping level and preparation conditions. Whereas the nominally pure CVD-ZnSe crystals had excess of Zn over stoichiometric composition, all the Fe-doped ZnSe crystals had an excess of chalcogen. This correlates with the results of the Zn-Se-Fe phase diagram analysis. Isothermal sections of T-x-y-z diagrams of ternary Zn-S-Fe, Zn-S-Cr and quarternary Zn-S-Fe-Cr, Zn-Se-Fe-Cr were reconstructed and experimentally confirmed by X-ray diffraction and Energy Dispersive X-ray spectroscopy (EDS) in the temperature range of 873 K - 1088 K. The homogeneity limits for ZnS:Cr:Fe and ZnSe:Cr:Fe phases have been determined. As a result of the control the intrinsic point defects Cr- and Fe-dopant levels we achieved the large quantities of differential efficiency of the produced ZnSe:Cr2 :Fe2 lasers. The research was financially supported by the Russian Foundation for Basic Research by the grant № 19-33-50118
Authors : A. Stanculescu(1), C. Breazu(1), M. Socol(1), A.-M. Solonaru(2), M. Grigoras(2), G. Petre(1,3), N. Preda(1), O. Rasoga(1), F. Stanculescu(3), G. Socol(4), M. Girtan(5)
Affiliations : 1. National Institute of Materials Physics, 405A Atomistilor Street, P.O. Box MG-7, Magurele, 077125 Romania, firstname.lastname@example.org; 2. P. Poni Institute of Macromolecular Chemistry, 41 A Gr. Ghica Voda Alley, 700487, Iasi, Romania; 3. University of Bucharest, Faculty of Physics, 405 Atomistilor Street, P.O. Box MG-11, Magurele, 077125 Romania; 4. National Institute for Laser, Plasma and Radiation Physics, 409 Atomistilor Street, PO Box MG-36, Magurele, 077125, Romania; 5. Laboratoire LPHIA, Université d’Angers, LUNAM, 2 Bd. Lavoisier 49045, Angers, France;
Resume : The limitation in the charge carrier injection and transport induced by the reduced diffusion length of exciton and reduced interfacial contact area between donor and acceptor in the classical bi-layer organic heterostructure can be overpassed using as active layer blends of donor and acceptor materials. This paper presents some studies of the organic heterostructures Al/donor:acceptor/ITO realised with mixed layers composed from poly(arylenevinylene)s containing carbazole units substituted at 2,7- and 3,6-positions as p type conduction donor and two different n type conduction acceptors: [6,6]-phenyl C61 butyric acid butyl ester or perylene tetracarboxidiimide, blended in 1:2 weight ratio. The mixed layer was deposited by Matrix assisted pulsed laser evaporation (MAPLE) using a Coherent ComplexPro 205 laser with =248 nm in the following experimental conditions: dichlorobenzene as solvent, fluence 250 mJ/cm2 and number of pulses=20000-30000. The properties of these mixed layers deposited on flat Al will be compared with those of the same mixed layers deposited by the same method on patterned Al obtained by the deposition of Al film on the 2D periodic structures with cylindrical shape realized by UV-Nanoimprint Lithography. The mixed layers have been characterized by spectroscopic (UV-VIS, PL) and microscopic (AFM, SEM) methods and the effect of the type of acceptor and nanopatterning on the optical and electrical properties of the heterostructure has been investigated.
Authors : 1. Pragya Tripathi, Janakarajan Ramkumar, Kantesh Balani
Affiliations : Materials Science Programme, Indian Institute of Technology, Kanpur 208016, India; Department of Mechanical Engineering, Indian Institute of Technology, Kanpur 208016, India; Department of Materials Science and Engineering, Indian Institute of Technology, Kanpur 208016, India.
Resume : In the current work, the effect of laser shock peening on chromium (Cr) based electrochemical coatings consisting of 3 mol% yttria stabilized zirconia nanoparticles (YSZ) and carbon nanotubes (CNT) as reinforcements i.e. Cr-YSZ, Cr-CNT and hybrid coating Cr-YSZ-CNT is studied. Coatings were deposited from eco-friendly trivalent Cr solution on steel substrate as a suitable strategy to further enhance mechanical and tribological properties of protective coatings. Cr exhibited an increased hardness after laser peening from ∼8 GPa to ∼9.4 GPa, whereas, maximum hardness value upto ~26 GPa was obtained for Cr-YSZ-CNT hybrid coating system. Enhanced hardness might be accredited to high compressive residual stresses ranging from 634 to 1757 MPa, induced as a result of laser peening. Minimum wear rate of ∼1.8×10−5 mm3/Nm by fretting wear test is recorded in the Cr matrix of laser peened hybrid coating, and a maximum dislocation density of ∼3.0×1016 m−2 was observed which accrue on synergistic reinforcement with YSZ and CNT. An overall improvement in mechanical and tribological properties indicated by low wear constant of the order ~10−6 was achieved after laser shock peening. Addition of YSZ strengthens the Cr matrix, whereas, multi-functionality of CNT provides lubrication along with matrix strengthening as well as bridging effect to crack propagation. Therefore, synergistic role of YSZ and CNT in Cr matrix combined with the laser peening treatment lead to superior properties of coating (Cr-YSZ-CNT) capable enough to limit the problems of wear and erosion in various industrial applications such as aerospace, gar turbines, automotive etc. Keywords: Electro-deposition, Cr coating, Yttria stabilized zirconia (YSZ), carbon nano-tube (CNT), Laser peening, Fretting
Authors : Eman Alhajji, † Wenxi Wang, † Wenli Zhang,† and Husam N. Alshareef*†
Affiliations : † Materials Science and Engineering, Physical Science and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia * E-mail: email@example.com (H. N. Alshareef)
Resume : Lithium-sulfur (Li-S) battery is a promising next-generation rechargeable battery with high energy density. Given the outstanding capacities of sulfur (1675 mAh g−1) and lithium metal (3861 mAh g−1), Li-S battery theoretically delivers an ultra-high energy density of 2567 Wh kg−1. However, this energy density cannot be realized due to the shuttling of polysulfide intermediates between the cathode and anode, which causes serious degradation to the cycling stability of a Li-S battery. In this work, a facile laser scribing method is utilized to synthesize a three-dimensional porous graphene interlayer. Besides simplicity and scalability, the synthesis of LSG is conducted at ambient conditions and involves no toxic solvents, which makes this process very attractive for Li-S battery applications. The hierarchical porosity of the free-standing LSG prevents the shuttling of the polysulfide intermediates. Therefore, Li-S battery with LSG interlayer exhibits a high specific capacity of 1160 mAh g-1 at 0.25C with an excellent capacity retention of 80.4%. This is one of the best reported values for Li-S batteries.
Authors : V. Dinca1, L.E. Sima2, M. Icriverzi2,3, L. Rusen1, A. Bonciu1,4, A. Roseanu2
Affiliations : 1National Institute for Lasers, Plasma and Radiation Physics, Bucharest, Romania 2Institute of Biochemistry of the Romanian Academy IBAR, Bucharest, Romania 3University of Bucharest, Faculty of Biology, Bucharest, Romania 4University of Bucharest, Faculty of Physics, Bucharest, Romania
Resume : In this work, complex composite coatings based on biodegradable PEG-PCL copolymer and the two bioactive factors, Lf and HA were created via a laser evaporation technique. Scanning Electron Microscopy, EDAX, contact angle and surface energy of the analyzed coatings were correlated to biological response on both short and longer term (72h, respectively 28 days). Human MSC were cultured on the developed coatings and viability, proliferation and morphology were evaluated. All surfaces were shown not to exhibit toxicity, as confirmed by LIVE/DEAD assay. Lf-HA composite exhibited an increase in osteogenic differentiation of hMSC cells, results supported by ALP and mineralization assays. This is the first report about biodegradable composite layers directing osteogenic differentiation from hMSCs and the results indicated that the biodegradable layers have great potential for application in bone regeneration.
Authors : Daeho Kim
Affiliations : Nano Hybrid Research Center, Korea Electrotechnology Research Institute, Changwon-city, KOREA
Resume : High-temperature thermal treatment is a fundamental method to enhance the crystallinity or to recover its intrinsic properties of nanomaterials. However, the indirect and time-consuming conventional heating methods have hindered high-quality material production with thermally weak inclusions or its applicability due to limited treatment temperatures of such as transparent or flexible substrates. Here, it is introduced the microwave ‘induction’ heating as a selective and fast heating method for conductive thin film. In different with the conventional microwave dielectric heating for electrically polarized molecules, the microwave induction heating has a mechanism that strong current induced by an oscillating magnetic field in giga-hertz frequency generates ohmic heat in conduction thin film. A 20nm-thick silver thin film sputtered on a 5mm-thick glass substrate for low thermal emissivity coating has been selectively heated more than 550oC in 200ms without thermal damage by the microwave induction heating, while the temperature of the glass substrate is maintained around room temperature. The surface resistance of the silver thin film is reduced to near 30% due to crystallinity enhancement, in results, reflectance in the IR region and transmittance in the VIS region are increased.
Authors : Curcio M. (1), Laezza A. (1), De Bonis A. (1), Bochicchio B. (1), Pepe A. (1), Ciarfaglia N. (1), Brutti S. (2), Santagata A. (3), Galasso A.(1), Teghil R. (1)
Affiliations : (1) Dipartimento di Scienze, Università della Basilicata, Potenza, Italy (2) Dipartimento di Chimica, Università di Roma La Sapienza, Roma,Italy (3) ISM-CNR, Tito Scalo (PZ), Italy
Resume : Lithium-ion batteries are widely used for widespread applications ranging from portable devices to electric vehicles. However, for developing a high-performance lithium-ion battery further improvements are necessary in term of both electrical performances and safety. In order to accomplish these issues, the design of new composite separators is recommended. The introduction of ceramic nanoparticles, such as alumina, titania, silica or ceria nanoparticles, is expected to impart high thermal stability, good wettability and ion conductivity to the separator. Here ceramic nanoparticles were produced by pulsed laser ablation in liquid, a powerful method for metal oxides nanoparticles (MONPs) synthesis. The effects of pulse duration and wavelengths on composition and size distribution of the nanoparticles were investigated. These particles were thereafter employed to fabricate MONPs/ poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HPF) as separators in batteries by electrospinning technique, a simple and straightforward system to prepare nano or microfiber membranes characterized by high porosity and surface area. According to our results, these MONPs/PVDF-HPF composite membranes exhibit superior thermal stability (in term of thermal shrinkage), electrolyte-philicity, electrolyte uptake and retention.
Authors : Pablo ACOSTA ALBA, Joris AUBIN, Fulvio MAZZAMUTO, Sébastien KERDILES
Affiliations : Université Grenoble Alpes CEA-LETI,SCREEN-LASSE, SCREEN-LASSE, Université Grenoble Alpes CEA-LETI
Resume : UV nanosecond laser annealing (UVNLA) is a very attractive alternative to conventional furnace methods. Thanks to the low absorption depth and the extremely fast heating, UVNLA is a key technology when very low thermal budgets are mandatory. Most UVNLA processes are based on liquid phase recrystallization. In this paper, we investigate UVNLA solid phase recrystallization with an overall thermal budget compatible with 3D-sequential integration. We started from 22 nm thick SOI substrates. Dopants were introduced by ion implantation with conditions leading to a partial amorphization of the silicon layer. Then, we investigated laser annealing conditions with multiple irradiations at the same location using energy densities lower than the melting threshold. Those experiments were performed in a SCREEN LT3100 platform (XeCl 308nm, 100-200ns range). With this sub-melt approach, we observe a progressive solid phase recrystalliza-tion of the amorphous Si layer from the bottom crystalline seed, resulting in a total crystal recovery. Moreover, from sheet resistance measurements, we showed that the resistivity obtained by this process was lower than the ones obtained with melt conditions or high temperature reference process. Dopant activation was therefore most likely higher. We also confirmed by AFM that the Si surface remained very smooth. We thus demonstrated that solid phase recrystallization induced by UVNLA was fully compatible with very low thermal budget CMOS integration
Authors : Ro.G. Nikov1, N.N. Nedyalkov1, A.Og. Dikovska1, D.B. Karashanova2
Affiliations : 1 Institute of Electronics, Bulgarian Academy of Sciences, 72 Tsarigradsko Chaussee, Sofia 1784, Bulgaria 2 Institute of Optical Materials and Technologies, Bulgarian Academy of Sciences, G. Bonchev Street, bl. 109, Sofia 1113, Bulgaria
Resume : This study presents results for nanosecond laser ablation of composite thin films immersed in liquids. Composite films are obtained using two different approaches. The first approach involves the subsequent deposition of thin layers of different materials. In the second, a classical on-axis pulsed laser deposition technology is used, where the target consists of two sectors with different composition. Using these approaches, multicomponent films containing ZnO, TiO, Ag, Au, Pd, and Pt are deposited on a substrate. The as-prepared multicomponent samples are then immersed in liquid media and irradiated by nanosecond laser pulses. This results in production of colloids composed by multicomponent nanoparticles. The optical properties of the colloids were evaluated by optical transmittance measurements in the UV– VIS spectral range. Transmission electron microscopy was used to visualize the nanostructures formed in the solution as well as to evaluate of their size distribution. On the basis of selected area electron diffraction, the phase composition of the samples was determined.
Authors : P. Gomez, A. Mariscal, J. Gonzalo, R. Serna
Affiliations : Laser Processing Group, Instituto de Optica, IO-CSIC, Serrano 121, 28006 Madrid, Spain
Resume : White light emitting materials have been studied extensively in the last years, due to their high efficiency and low cost, for potential application in a wide range of fields, such as microelectronics, spintronic, optics and optoelectronics. To that purpose, rare earth ions can be combined with powder phosphors or other lanthanides. In particular, Europium is very attractive for lighting applications, since it possesses two oxidation states, which show different emission characteristics: 4f intra-transitions in the case of Eu3 , and broadband emission in the blue visible spectrum in the case of Eu2 . In this work we study the effect of the structure and annealing treatment on the photoluminescence (PL) response of europium oxide (Eu2O3) thin layers prepared by pulsed laser deposition (PLD) in vacuum (P= 200 Pa) on Si substrates held at room temperature. Amorphous aluminum oxide (a-Al2O3) layers produced by PLD have been used as buffer and capping layers to modify the structure of Eu2O3 films and protect europium from air oxidation. PL emission is activated by post-deposition annealing at 300ºC in air or nitrogen atmospheres. The samples crystallize upon annealing, the crystalline phase being dependent on the sample structure and annealing gas. Films annealed in air show the characteristic Eu3 PL emission in the red region of the visible spectrum, while controlling the nitrogen atmosphere during annealing allows obtaining a characteristic Eu2 PL emission.
Authors : Mado Logotheti (a), Symeon Papazoglou (a), Matthew Praeger (b), Ben Mills (b), Filimon Zacharatos (a), Robert W. Eason (b), Ioanna Zergioti (a)
Affiliations : (a) School of Applied Mathematical and Physical Sciences, Physics Department, National Technical University of Athens, Athens, Greece (b) Optoelectronics Research Centre, University of Southampton, Southampton, SO17 1BJ, UK
Resume : Two-dimensional (2D) materials have attracted significant attention during the last decade owing to their unique optoelectronic properties, which find use in numerous applications including touch sensors, displays and emitters. Current techniques do allow transfer of 2D materials from the growth substrates to a substrate of interest, i.e. for device fabrication, with a high degree of precision and resolution. The large number of steps involved however, (polymer coating, etching of metal support foils, washing steps, post-patterning) results in costly and time-consuming processes that limit their scalability and ease of use. In this work, we report our latest results on the laser transfer of graphene on rigid and flexible substrates using the Laser-Induced Backward Transfer (LIBT) technique, by employing both fs and ns lasers. Using LIBT, single step and micron-scale precise transfer of graphene and MoS2 has been achieved without any post-processing. Additionally, we have employed LIBT for the intact transfer of pixels comprising thin and ultra-thin Au films on polymer substrates, highlighting the potential application of this digital process for 2D/ thin metal interfaces. The transferred structures are fully characterized using Raman spectroscopy, SEM and AFM. These results hold great promise in minimizing the number of transfer steps for 2D and ultra-thin metallic materials, enabling novel device fabrication in a rapid and cost-effective way, with micron-scale precision.
Authors : Kenane, A.(1)(2), Rasoga, O.(2), Breazu, C.*(2), Popescu-Pelin, G.(3), Socol, G(3), Yahiaoui, A.(1), Hachemaoui, A.(1), Benkouider, A.M.(1), Pasuk, I.(2), Matei, E.(2), Costas, A.(2), Stan, G.E.(2), Galca, A.C. (2) & Stanculescu, A. (2).
Affiliations : (1)Laboratory of Organic Chemistry Macromolecular and Materials, Faculty of Exact Sciences, University of Mascara, 29000 Mascara, Algeria (2)National Institute of Materials Physics, 405A Atomistilor, 077125 Magurele, Romania (3)National Institute for Laser, Plasma and Radiation Physics, 409 Atomistilor, 077125 Magurele, Romania
Resume : Polyaniline (PANI) and/or poly(ortho-anisidine) (Poly(o-ANIS)) intercalated in organo-modified clay (OMt) are composites with an extended π-conjugated backbone, combining the organic semiconductor properties and the characteristics of the inorganic compound. In this study, the nanocomposites have been prepared in thin film form by matrix-assisted pulsed laser evaporation (MAPLE). The targets were prepared from polymers and/or nanocomposites synthesized by oxidative chemical polymerization, immersed in DMSO and frozen in LN2. Optical, structural and electrical properties of the obtained thin films are inferred from conventional spectroscopies (UV-Vis and FTIR), X-Ray diffraction, Scanning Electron Microscopy, Atomic Force Microscopy and current-voltage measurements. The results are discussed with respect to the ratio between PANI / Poly(o-ANIS) intercalated in OMt and also with the films of pristine polymers. All authors acknowledge Romanian Ministry of Education and Research in the framework of PN-III-P1-1.2-PCCDI-2017-0062 (no. 58PCCDI/2018), Core Program PN19-03 (no. 21N/08.02.2019) and PFE-CDI-339 (no. 12PFE/2018). A.K. acknowledges Algerian Ministry of Higher Education and Scientific Research for the received mobility research grant (no. 304/PNE/2018-2019) in the frame of Algerian Programme National Exceptionnel (PNE).
Authors : Harim Oh, Minseok Seo, Jaeyong Kim, Junho Lee, Myeongkyu Lee
Affiliations : Department of Materials Science and Engineering, Yonsei University, Seoul 120-749, Korea
Resume : Dewetting is a spontaneous phenomenon that refers to the decomposition of a film into droplets or nanoparticles on substrate. Laser dewetting has proven effective in producing not only monometallic nanoparicle arrays but also bimetallic alloy nanoparticles with tunable surface plasmon resonances. However, the particles produced via laser irradiation typically exhibit a wide size distribution, and the average particle size is determined by the initial film thickness. In this study, we show that if metal thin films are thermally annealed prior to laser dewetting, nanoparticles with a much narrower size distribution can be produced. This is attributed to a morphological change in the film occuring as a result of heat treatment. Experimental results obtained using a pulsed Nd :YAG laser for Ag thin films are presented and discussed.
Authors : Herbert Legall, Jörn Bonse, Jörg Krüger
Affiliations : Bundesanstalt für Materialforschung und -prüfung (BAM), Unter den Eichen 87, 12205 Berlin, Germany
Resume : Ultrafast laser processing can be accompanied by significant emission of unwanted X-ray radiation. Machining at laser peak intensities above 10^13 W/cm^2 and at high repetition rates in the multi 100 kHz range has a risk of exceeding the statutory X-ray exposure limits . Therefore, radiation protection in ultrashort laser material processing became a new and industrially relevant focus of interest. Additionally, the need for a safe operation of the laser itself must be considered. Utilizing steel and aluminum as shielding materials, adequate material thicknesses for reliable X-ray protection were calculated using measured X-ray spectra for laser treatment of tungsten with 925 fs pulse duration at a center wavelength of 1030 nm, a repetition rate of 400 kHz, and a peak intensity of 2.6×10^14 W/cm^2. Here, the relevant X-ray emission is limited to photon energies below 30 keV.  H. Legall et al., Applied Physics A 124 (2018) 407.
Authors : Karin Schwibbert, Camilo Florian, Dorothea Thiele, Jörg Krüger, Jörn Bonse
Affiliations : Bundesanstalt für Materialforschung und -prüfung (BAM), Unter den Eichen 87, 12205 Berlin, Germany
Resume : Bacterial biofilm formation poses high risks in many medical and industrial applications. Hence, various strategies are currently developed, tested and improved to realize anti-bacterial surface properties through additional surface functionalization steps. In this study, contact-less and aseptic large-area femtosecond laser scan processing is employed to generate different surface structures in the nanometer- to micrometer-scale on technical materials, i.e. titanium-alloy, steel, and polymer. The processed surfaces were characterized by optical and scanning electron microscopy and subjected to bacterial colonization studies with Escherichia coli and Staphylococcus aureus as test strains. For each material, the results of the fs-laser treated surfaces are compared to that obtained on polished (non-irradiated) surfaces as a reference. In all cases, a remarkably different adhesion behavior of the two types of bacteria is found, suggesting an influence of their geometrical size and shape.
Authors : Faezeh Kazemi1, Jens Bauer1, Thomas Arnold1, 2, Pierre Lorenz1, Martin Ehrhardt1, and Klaus Zimmer1
Affiliations : 1) Leibniz Institute of Surface Engineering (IOM), Permoserstraße 15, 04318 Leipzig, Germany 2) Faculty of Mechanical Science and Engineering, Institute of Manufacturing Science and Engineering, Technische Universität Dresden, Dresden, Germany
Resume : The machining of technical glass with beam technologies enables novel fabrication processes for innovative optical elements with free form surfaces but require technologies for high-precision, low roughness machining. Reactive plasma etching of N-BK7 is challenging due to the complex composition of glass and feature therefore potential limits related to forming of a residues layer. The presentation demonstrates a sequential plasma etching and laser cleaning process for N-BK7 glass machining. First the glass is etched with a fluorine gas containing reactive plasma jet (RPJ) resulting in an etched surface containing also residues that change the surface composition. After RPJ etching the residues are removed by pulsed UV laser irradiation without ablation of the glass. RPJ etching and laser ablation are applied repeatedly enabling a prolonged, stabile etching process that is required for industrial machining processes. First results of the combination process of RPJ etching and laser ablation are shown and discussed. Thus, RPJ etching and laser ablation (RPJE-LA) of N-BK7 are studied separately showing the limitations. Thereafter, important process characteristics RPJE-LA approach such as etching rates, surface morphologies and surface roughness are given. Further, selected results of the surface composition alterations are given. The mechanism RPJE-LA are discussed in relation to the characteristics both process steps and the experimental finding of the RPJE-LA.
Authors : L. Nedelcu 1, L. Trupina 1, C. Chirila 1, M. G. Banciu 1, G. Annino 2, D. Passerieux 3, A. Ghalem 3, L. Huitema 3, A. Crunteanu 3, P. Carles 4, C. Constantinescu 4
Affiliations : 1 National Institute of Materials Physics, Bucharest-Magurele, Romania 2 Istituto per i Processi Chimico-Fisici, IPCF-CNR, Pisa, Italy 3 Xlim UMR7252 CNRS/ Université de Limoges, 87060 Limoges, France 4 IRCER UMR 7315 CNRS/ Université de Limoges, 87068 Limoges, France
Resume : (Ba, Sr)TiO3 (BST) ferroelectric solid solutions with Curie point close to room temperature have been extensively investigated over the last 30 years for their integration in microwave (MW) tunable devices. Recently, several terahertz applications based on BST thin films have been reported. In this work, we present and discuss on the THz and MW properties of the BST thick films grown on MgO(001) and Al2O3(0001) substrates by using pulsed laser deposition. As a result of a parametric study, single-phase samples with thicknesses between 2 and 5 µm are achieved. THz time-domain spectroscopy measurements in transmission are carried out successively on substrates before and after the BST film deposition. In order to extract the dielectric properties of the films from the THz data, the substrate is considered as an overmoded dielectric resonator, characterized by a regular series of resonance peaks in the THz transmission spectrum, loaded by the BST thin film. In this system, the complex permittivity of the film sample is obtained by the analysis of the shift and attenuation of the peaks induced by the sample, in a close analogy to dielectric measurements by means of Fabry-Perot resonators. The complex permittivity in MW domain of the obtained films are accurately measured at 12.5 GHz using a resonant cavity method. The tunability of the ferroelectric layers are determined by integrating them in planar inter-digitated capacitors (IDC) fabricated using standard microfabrication technologies. The MW characterization of the IDCs is performed in reflection configuration under various applied electrical fields. A 40 % tunability of the permittivity under an applied field of 100 kV/cm is achieved at 30 GHz for structures with optimized topologies.
Authors : Gaspar, G.(1), Baptista, J.M.*(1, 2), Santos, D.R.(1, 3), Correia, J.P.(3), Wijayantha, U.K.G.(2), Lobato, K.(1)
Affiliations : (1) Instituto Dom Luiz, Faculdade de Ciências, Universidade de Lisboa, 1749-016 Lisboa, Portugal; (2) Energy Research Laboratory (ERL), Department of Chemistry, Loughborough University, Leicester LE11 3TU, United Kingdom; (3) Centro de Química Estrutural, Faculdade de Ciências, Universidade de Lisboa, 1749-016 Lisboa, Portugal * lead presenter
Resume : In highly porous carbon electrodes, a large fraction of pores are inaccessible to the electrolyte, which reduces the capacitance. This effect is accentuated at high charge/discharge current densities. Creating additional channels in the porous electrode has been proposed to overcome this limitation . Ion diffusion can be monitored through Probe Beam Deflection (PBD) . In short, this technique allows the detection of mass flows in the electrolyte diffusion layer due to changes in the concentration gradients (and hence the refractive index) near the electrode surface. In this particular case, the beam initially travels parallel to the electrode/electrolyte interface and its angle of deflection towards or away from the interface is dictated by the ionic concentration variation. This work reports on how ionic diffusion is altered when porous carbon-based electrodes are modified by opening up channels and trenches. The electrodes were modified using a 1064 nm Nd:YAG pulsed laser (spot diameter 50 um). Laser rastering speed and pattern, pulse energy and repetition rate were varied to alter the morphology of the porous electrode. Complementarily to PBD, cyclic voltammetry and galvanostatic charge/discharge measurements were also undertaken to understand how performance metrics are dependent on electrode modification.  J.Y. Hwang et al. Adv. Funct. Mater. 27 (2017) 1605745  F. Decker et al. J. Electroanal. Chem. Interf. Electrochem. 228 (1987) 481-486
Authors : Wirginia Pilarczyk
Affiliations : Silesian University of Technology, Faculty of Mechanical Engineering, Gliwice, Poland
Resume : Amorphous materials are potential material for wide application because of their unique mechanical, physical, and chemical properties. However, its industrial application is not widespread because of limited size and shape. It can be concluded that the production of this type of Fe-based material in the form of direct metal deposition coatings can be an interesting technological achievement. The possibilities of generating metastable materials with the use of generative technologies have not been fully investigated yet and phenomena accompanying coating of the consecutive layers of amorphous/ crystalline alloys have not been explained yet. This research aimed to make specimens having the geometry of a plate using the DMD (Direct Metal Deposition) method as well as to investigate the effect of the number of layers on the structure, nanohardness and Young modulus of fabricated elements. In order to measure the size of the discontinuity of the structure and to determine the shape of the revealed defects, metallographic observations were made with the use of the scanning electron microscope Supra 35 by Zeiss and optical microscope Axio Observer by Zeiss. Because of the width of the particular additive zone, triboindenter, which enabled the measurement in the scope of between ten to twenty micrometres, was used to examine nanohardness and reduced Young module. Acknowledgements This publication and conference participation was financed by the Ministry of Science and Higher Education of Poland as the statutory financial grant of the Faculty of Mechanical Engineering SUT and Rector's Grant in the field of research and development, SUT, no.: 10/010/RGJ19/0272.
Authors : Monica Scarisoreanu 1, Claudiu Fleaca 1, Iuliana Morjan1 , Lavinia Gavrila-Florescu1, Elena Dutu 1, Evghenii Goncearenco 1, Florian Dumitrache 1, Valentin Teodorescu2, Crina Anastasescu 3, Ioan Balint 3
Affiliations : 1 National Institute for Lasers, Plasma and Radiation Physics, Magurele, Romania; 2 National Institute of Materials Physics, Magurele, Romania; 3 Romanian Acad, Inst Phys Chem Ilie Murgulescu, 202 Spl Independentei, Bucharest 060021, Romania;
Resume : TiO2 is most extensively studied material for its wide applications in sensors, pigments and photocatalysis. When nanometer particles of TiO2 are used, the catalytic activity is expected to be enhanced due to not only the increase of surface area but also the change of surface property such as defects. Herein, we report on the titania doping with vanadium (V+5) and tungsten (W+6) as strategy to reduce the band gap energy of the semiconductor and to decrease in electron-hole recombination rate. Both vanadium and tungsten can substitute the titanium (Ti+4) ion in the titania lattice because of similar radii of the involved cations. Optical, morphological and structural properties of the samples obtained by laser pyrolysis technique, have been revealed by UV-Vis spectroscopy, infrared spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM) and high-resolution electron microscopy techniques. The phase composition of the nanoparticle system contains a mixture of anatase and rutile, with a preponderance of the anatase phase (90%) and with mean particle size of about 28 nm. The increase of dopant concentration on the essential structural properties of V/W-TiO2 nanopowders has been determined to be a decrease of the TiO2-anatase phase ratio and of the particle mean diameter value (to about 20nm). The UV-Vis diffuse reflectance spectra showed an absorption shift in V/W-doped TiO2 nanoparticles to longer wavelengths, thus demonstrating an enhancement of the absorption in the visible spectrum.
Authors : N.E. Stankova1, N.N. Nedyalkov1, A.S. Nikolov1, P.A. Atanasov1, E. Iordanova2, G. Yankov2, V. Mihajlov2, L. Aleksandrov3, R. Iordanova3, K.N. Kolev4
Affiliations : 1 Institute of Electronics, Bulgarian Academy of Sciences, 72 Tzarigradsko Chaussee blvd., 1784 Sofia, Bulgaria, 2 Institute of Solid State Physics, Bulgarian Academy of Sciences, 72 Tsarigradsko shousse blvd., 1784 Sofia, Bulgaria, 3 Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, Acad. Georgi Bonchev str. bld.11, 1113 Sofia, Bulgaria, 4 Institute of Physical Chemistry, Bulgarian Academy of Sciences, Acad. Georgi Bonchev str. bld.11, 1113 Sofia, Bulgaria
Resume : We present results on three dimensional (3D) photonic effects in different optically transparent media like flexible PDMS polymer and noble metal enriched borosilicate glass induced by direct laser processing. Short and ultrashort laser pulses generated in the UV-ViS-NIR spectrum are used for direct laser patterning or ablation in local surface or volume area without limit of the planar structures. The special periodicity of the pattern's structure and the optical waveguide arrays formation, and also the tuning of the plasmon-resonance of the nobel metals doped, are explored by varying specific laser parameters and set-up arrangements. The elasticity of PDMS allows tunable control of the structures’ parameters and hence of the photonic effects induced. Photonic (optical and plasmonic) effects in the borosilicate glasses arised after further thermal annealing and/or additional irradiation with laser light. The methods employed enable easy controllable fabrication approach of photonic elements spanning from skin or implantable wearables for healthcare monitoring to implantable neural interface devices as well as the chip-scaled optical interconnects. Different techniques (UV-Vis spectroscopy, x-ray photoelectron spectroscopy, optical and scanning electron microscopy) are used for studying and comparing the optical, compositional and structural properties of both areas - pristine and laser treated ones.
Authors : Z. SKANDERI1, A. DJEBAILI1*, A. LAKHZOUM2
Affiliations : 1 Laboratory of chemistry and environmental chemistry L.C.C.E - University of Batna- 2 Faculty of Biology. University of Batna 2- 05000- Algeria
Resume : The first originality of the experiments we carried out consists of the use of a laser beam as a double agent: simultaneously as activation agent inducing the isomerization reaction of the PA, and for the Raman diffusion. The laser beam power P(λ) is equivalent to the temperature T of isotherm i of isomerization reaction. The second originality consists of use of multichannel spectroscopy which enables the simultaneous observation of both reactants (PAcis) and product (PAtrans) in the same time, since PAcis absorption band and PAtrans absorption band are clearly shifted on a band of 512 diodes Then we have a double simultaneity (i) In one hand the heating and the diffusion of the laser beam, (ii) On the other hand the steady measurement of the concentrations. We elaborate a numerical model reproducing the Raman experiment within 5 % error. The rate constants, activation energy values, Arrhenius factors and linear regression coefficients are obtain with a small error. The kinetic results obtained, such as reaction orders values obtained, varying from 1/2 to 2/3, showed clearly that, the isomerization reaction of undoped P.A. remains a complex process. The reaction order of 2/3 seems to be the most appropriate value in this case, since it refers to a solid state reaction propagation, where the reaction rate is controlled by a three dimensional development of active centers, in agreement with Sestak and Berggren theory.
Authors : I.R. KRIBA1, A. DJEBAILI1*; Z. SKANDERI2, A. LAKHZOUM 3
Affiliations : 1 Laboratory of chemistry and environmental chemistry - University of Batna 1- Algeria 2 Institute of Hygiene and Industrial Safety- University of Batna 2- Algeria 3 Faculty of Biology - University of Batna 2- Algeria
Resume : This work presents a numerical resolution of heat distribution equation of pulsed laser beam impact on a sample of oriented polyacetylene characterized by multichannal Raman spectroscopy. The method is based on finite elements theory which allowed the determination of: (i) The temperature of laser impact zone , (ii) The propagation zone of isomerization of a polyacetylene sample. A computer program was been developed for this purpose. Key Words: Multichannal Raman spectroscopy, Oriented Polyacetylene, numerical resolution, finite elements, isomerization
Authors : Tristan O. Nagy, Morris J.J. Weimerskirch, Fabian Kraft, Ulrich Pacher
Affiliations : University of Vienna, Physical Chemistry; University of Vienna, Physics of Nanostructured Materials; University of Vienna, Physics of Nanostructured Materials; University of Vienna, Physical Chemistry
Resume : We show the performance of fully automated 1064 nm picosecond LIBS on samples generated by Laser Metal Deposition (LMD) as well as Cold Metal Transfer (CMT) welding. The first method uses micrometer-sized metal powders of various composition mixed in an inert gas jet and coaxially directed onto the meltpool generated by a CW-laser on the workpiece’s surface. This way, chemically graded 3-dimensional structures can be generated based on complex physicochemical models, resulting in functionally graded workpieces with laterally varying physical properties . CMT has become a standard-technique to join light metal parts of different composition, shape and thickness in the automotive and aerospace industry. In particular the latter one requires high-standard quality and process control in real time. In both cases LIBS can be used as a parametrisation method for new buildup processes as well as a real-time online quality control tool with potential to by fed back in the LMD-process via closed-loop coupling. We present various lateral and in-depth chemical mapping analyses of multi-layer and multi-material parts, validated via metallographic cross-sections and scanning electron microscopy/x-ray spectroscopy.  https://doi.org/10.1016/j.addma.2018.06.023  https://doi.org/10.1364/OE.27.004612  https://doi.org/10.1016/j.addma.2018.10.043
Authors : Gianina Popescu-Pelin1, Cristian Butnaru1, Izabela Jinga1, Felix Sima1, Gabriel Socol1
Affiliations : 1National Institute for Lasers, Plasma and Radiation Physics, Magurele 077125, Ilfov, Romania
Resume : We report on the development of novel coatings with improved composition and structure that enhance curative properties of Ti implants. Titanium implants functionalized with Se and Sr doped HA/β-TCP coatings (HA/β-TCP:Se/Sr) were achieved by combinatorial pulsed laser deposition (c-PLD) technique in order to identify the optimum elemental composition with respect to their biological features. FTIR evaluation of HA/β-TCP:Se/Sr samples offered information’s about the functional groups and covalent bonding and revealed the stoichiometric transfer. The elemental composition of the as-deposited coatings was determined from EDS and XPS measurements and pointed out the Se and Sr dopants content. The morphological features and the crystalline state of the as-deposited coatings was evaluated by scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses, respectively. The cytotoxicity, viability and proliferation of HA/β-TCP:Se/Sr were evaluated in order to establish the optimal concentration of Se and Sr. The aim of this study was to fabricate metallic implantable devices covered with thin films of HA/β-TCP:Se/Sr composite designed for bone tissue therapy that stimulate the osseointegration.
Authors : Ilias Fekas, Spyros Kassavetis, Spilios Dellis, Christos Kapnopoulos, Panos Patsalas
Affiliations : Physics Department, Aristotle University of Thessaloniki, Thessaloniki, GR-54124, Greece; Nanotechnology Lab LTFN, Physics Department, Aristotle University of Thessaloniki, Thessaloniki, GR-54124, Greece; Physics Department, Aristotle University of Thessaloniki, Thessaloniki, GR-54124, Greece; Nanotechnology Lab LTFN, Physics Department, Aristotle University of Thessaloniki, Thessaloniki, GR-54124; Physics Department, Aristotle University of Thessaloniki, Thessaloniki, GR-54124, Greece
Resume : Titanium Nitride (TiN) has emerged as a promising alternative plasmonic material that may outperform the traditional plasmonic metals, such as Au and Ag in terms of durability to high temperatures and/or to the high electric fields of concentrated light present in most realistic plasmonic applications. TiN is a well-known conductor of high mobility, widely used in the mainstream microelectronics industry, and it owes its electronic conductivity to the partially filled valenced orbitals that are not completely hybridized with the N-2p electrons and presents high optical response similar to that of Au, hence its golden optical appearance, when in stoichiometric form; non-stoichiometric TiNx>1 films are also reported and are predicted to exhibit Localized Surface Plasmon Resonance (LSPR) in red and Near-Infrared (NIR) ranges. TiN is usually grown in thin film form by sputter deposition, its bottom-up nanostructuring was not successful so far, and the formation of colloidal TiN is exceptionally rare, both due to the refractory character of TiN, which is a major obstacle for its wide range implementation. The scope of this work is the synthesis of colloidal TiN and TiNx nanoparticles with tunable LSPR from the visible to the NIR spectral ranges, thus covering the entire biological window, a property that can find use in many different biomedical applications, such as the healing of tumors by plasmonic hyperthermia. The TiN and TiNx nanoparticles (NPs) were fabricated by the following two steps process: a) picosecond laser ablation of thick TiN and TiNx thick films in liquid media for the synthesis of the Colloidal TiN NPs and b) nanosecond Laser irradiation of the Colloidal TIN NPs for the downsize the TiN NPs in the liquid media and the tuning of the LSPR. For this purpose, TiN films grown by UHV Reactive Magnetron Sputtering. The crystallinity, conductivity and stoichiometry of the films can substantially vary by varying the bias voltage applied to the substrate (Vb=0 to -120 V) and the substrate temperature (T=RT to 400 oC). The chemistry, crystallinity, optical properties, and the point defects of the target materials were evaluated by X-Ray Diffraction, X-Ray Photoelectron Spectroscopy, Spectroscopic Ellipsometry and Raman spectroscopy, respectively. Then, the major laser ablation parameters were investigated, in particular the wavelength (532, 355, 266 nm), fluence (1-30 mJ/cm2), and the number of pulses. The optical properties, the size, and the structure/defects of the produced TiN nanoparticles were assessed by optical transmittance spectroscopy, atomic force microscopy, and Raman spectroscopy, respectively.
Authors : Indranil Manna and Jyotsna Dutta Majumdar
Affiliations : Indian Institute of Technology Kharagpur
Resume : Laser Surface Cladding is a process of development of surface layer, by laser surface melting of the coating in the form of wire or powder and delivering the molten material on the surface of a substrate with minimum dilution at the interface. The process may be applied for the development of alloys, metal matrix composite and intermetallic covered surface on metallic substrate. In the present contribution, a detailed study on the development of compositionally graded surface by laser surface cladding has been presented. The detailed study would include development of compositionally graded metal matrix composite on mild steel substrate, and SiC dispersed aluminium composite on aluminium for wear resistance application. Laser surface processing has been carried out using continuous wave CO2 laser, or Diode laser. The effect of process variables on the microstructures, mechanical properties, and electrochemical property has been studied. Finally, the mechanism of wear and corrosion resistance has been established. Laser surface cladding under optimum process parameters leads to development of a defect free clad zone with a minimum heat affected zone. Laser power density and scan speed play important role in determining the thickness of the clad zone, microstructure and microhardness. The detailed structure-property-process parameters correlation for the laser surface cladding is established.
Authors : Iuliana Urzica(1), Agota Simon(1,2), Petre Catalin Logofatu(1), Cristian Udrea(1), Mihail Lucian Pascu(1,2)
Affiliations : (1) National Institute for Laser, Plasma and Radiation Physics,Magurele, Romania (2) Faculty of Physics, University of Bucharest, Magurele, Romania
Resume : Many living beings in nature, including the lotus leaf, rice leaf, butterfly wing and water-strider legs are the inspiration for many innovations and continue to serve as an invaluable resource to solve technical challenges. Such surfaces possess several unique beneficial properties, such as extreme water repellency, self-healing, self-cleaning, anti-bacterial, anti-corrosion, enhanced heat transfer, drag reduction and improved corrosion resistance. Recently, superhydrophobic surfaces, for which water contact angle is higher than 150° and sliding angle less than 10°, have received attention due to the many potential applications ranging from biological to industrial processes and usable/applicable properties, even in daily life. In this paper, an innovative, flexible and low-cost experimental set-up for producing superhydrophobic metal surfaces that are modeled by nanosecond laser ablation is shown. One of the goals of this patterned superhydrophobic metallic surfaces is to obtain a device to be used in samples surface preparation of materials such as: polymeric materials; out of these polydimethylsiloxane-PDMS, polyethylene terephthalate-PET, synthetic latex polymers, polyvinyl chloride-PVC materials are considered. The polymeric structures have the same properties as those of the metal pattern used to generate them and are employed in a large number of applications in: biology, food industry, marine industry and textile industry.
Authors : Niemczyk, A.*(1), Brajnicov, S. (2), Satulu, V. (2), Bonciu, A. (2), Baranowska, J.(1) & Mitu, B.(2), Dinescu, M. (2).
Affiliations : (1) West Pomeranian University of Technology, Szczecin, Faculty of Mechanical Engineering and Mechatronics, Department of Materials Technology; al. Piastów 19; 70-310 Szczecin, Poland (2) National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Str., Magurele Bucharest 077125 Romania
Resume : Matrix Assisted Pulsed Laser Evaporation (MAPLE) technique is lately receiving considerable attention due to its possibility to obtain a large variety of materials, such as delicate polymers, proteins, or biomaterials in the form of thin films. In this context, copolymers which present a particular complexity due to the diversity of the polymer chains are excellent candidates for synthesis using MAPLE technique. In this work, we present the results on the synthesis of poly(ethylene-co-vinyl acetate) (EVA) copolymer using a Nd:YAG laser with a repetition rate of 10 Hz which was irradiating the EVA copolymer dissolved in toluene and frozen in liquid nitrogen. The influence of the laser wavelength, fluence, number of pulses and the concentration of EVA in the target on the thin film properties was investigated. The morphology and topography of thin films were evaluated by means of Scanning Electron Microscopy and Atomic Force Microscopy techniques. The composition and chemical bonding was revealed upon using Fourier Transformed IR Spectroscopy and X-ray Photoelectron Spectroscopy. This approach allowed us to optimize the experimental conditions in order to obtain uniform depositions of EVA thin films with high degree of resemblance to the target composition.
Authors : Pui-Jung Chen*, Yung-Tang Nien
Affiliations : Department of Materials Science and Engineering, National Formosa University
Resume : In this study, cerium-doped yttrium aluminum garnet (YAG:Ce) blended with SiO2 to improve the sintering density was prepared by two different processes, one is solid state reaction (SSR) and another is laser sintering (LS). By using instruments of x-ray diffractometer (XRD), scanning electron microscope (SEM) and x-ray photoelectron spectrometer (XPS), the crystal structure, surface morphology, and dopant valence state of the above SSR and LS YAG:Ce ceramics were compared, respectively. XRD patterns presented both processes could transform precursors successfully into a YAG phase with no detectable impurity phase. SEM images revealed the surface morphologies of SSR and LS were crystallites with xylem-shaped structures and coral-shaped structures, respectively. XPS spectra revealed that the SSR process had one additional peak and high peak intensities of Ce4+ as compared to LS. The ratios of Ce3+ to Ce4+ was 8:9 and 5:4 in SSR and LS, respectively. Based on the above XPS spectra, it is believed that a sharp temperature increase could deplete the surrounding oxygen as laser beams scanned on precursors, resulting a reduction of valence state of Ce from +4 to +3 in the LS process. Therefore, the better photoluminescence as well as higher fluorescence efficiency in LS process than those in SSR process was mainly caused by their different valence states. The detailed will be present in the conference.
Authors : Beatrice Atzl (1), Matthias Domke (2), Johannes Zehetner (2), Bettina Friedel*(1)
Affiliations : (1) Research Centre Energy, University of Applied Sciences Vorarlberg, Hochschulstrasse 1, 6850 Dornbirn, Austria; (2) Research Centre for Microtechnology, University of Applied Sciences Vorarlberg, Hochschulstrasse 1, 6850 Dornbirn, Austria
Resume : Silicon carbide (SiC) is a wide-band gap semiconductor, known for its excellent electronic properties and durability. Beyond its typical application in high power transistors, SiC recently received a new boost of research interest from the LED, battery and catalysis community. However, an obstacle in those fields is the common preparation of semiconductor grade SiC starting with the growth of expensive single crystalline wafers, even if actually porous, nanostructured or powdered material is needed. Here, we present first results on a novel approach to tackle this problem: Localized synthesis of SiC by laser-induced carbothermal reduction of silicon oxycarbide (SiOC). We will discuss and share our latest insights of this promising process, e.g. how the underlying multistep reduction reactions within SiOC require careful adjustment of lasing parameters and atmosphere to proceed with appropriate balance, to lead to SiC formation. Apart from the vital Si/C ratio and morphology of the SiOC, which is customized by chemical synthesis, this is discussed with regard to its heat capacity and thermal conductivity, but also thermal onsets of the reactions, effect of dopants, reaction dynamics and kinetics. Finally, first physical characteristics of the laser-derived SiC will be presented. Once the process is understood and thus controllable, it would make a fine technique to simply write SiC semiconductor tracks, create structured layers or particles, just by lasing.
Authors : Oana Gherasim1,2, Alina Maria Holban3, Alexandru Mihai Grumezescu2,*, Valentina Grumezescu1, Ecaterina Andronescu2
Affiliations : 1National Institute for Lasers, Plasma & Radiation Physics, Lasers Department, P.O.Box MG-36, Bucharest-Magurele, Romania; 2University Politehnica of Bucharest, Faculty of Applied Chemistry and Materials Science, Department of Science and Engineering of Oxidic Materials and Nanomaterials, Polizu Street no 1-7, 011061 Bucharest, Romania; 3Faculty of Biology, University of Bucharest, Microbiology Immunology Department, Aleea Portocalilor 1-3, Sector 5, 77206-Bucharest, Romania
Resume : The surgical intervention on hard tissues has emerged in the last years, therefore researchers, engineers and clinicians seek for efficient alternatives to develop tailored biomaterials. In this study we have developed an innovative thin film containing hydroxyapatite and silver nanoparticles, with good biocompatibility and antimicrobial effect, to be used in hard tissue engineering. Bioactive coatings were obtained by MAPLE (matrix assisted pulsed laser evaporation) and physico-chemically characterized by DRX, DTA-TG, and SEM. Biocompatibility was assessed by fluorescence microscopy and the MTT assay, on human diploid cells, while antimicrobial potential was analyzed in Gram positive and Gram negative opportunistic pathogens. The results revealed that the obtained materials are uniform and well organized, with the an average film thickness of 600nm. The developed nanostructured films presented a good biocompatibility in vitro, allowing for normal development and growth of human cells. On the other hand, the nanostructured thin film inhibited the attachment of microbial cells and also the formation of monospecific biofilms. Good biofilm inhibition was observed in Staphylococcus aureus and Pseudomonas aeruginosa strains, two of the most important opportunistic pathogens involved in device-associated infections and bone regeneration failure. The developed materials proved a good compatibility and an increased ability to limit microbial attachment and biofilm formation.
Authors : T. Aloui (1,2), N. Fourati (1), H. Guermazi (2), C. Constantinescu (3), R. Lucas (3), S. Guermazi (2), C. Zerrouki (1)
Affiliations : (1) SATIE / UMR CNRS 8029, ENS Paris-Saclay, Cnam, Cergy Paris-Université, France; (2) PMISI, Faculty of Sciences of Sfax, University of Sfax, 3038, Tunisia; (3) IRCER / UMR CNRS 7315, Centre Européen de la Céramique (CEC), France.
Resume : Ternary metal oxides are a promising class of multifunctional materials that can efficiently fulfill the major energy and environmental needs. Nickel molybdate (NiMoO4) particularly, presents excellent properties in addition to its non-toxicity, cost-efficiency and chemical stability, that render it suitable for a broad domain of applications. The present study focusses on NiMoO4 particles, synthesised by co-precipitation method in aqueous solution at room temperature. The resulting powder was subsequently characterized by scanning electron microscopy and energy dispersive X-ray spectrometry (SEM/EDS). Besides confirming the expected stoichiometry, the analysis revealed homogeneous distribution of polydisperse non-aggregated microsheets-like NiMoO4, crystallized in α-form, as shown by X-ray diffraction (XRD). The main objective of this communication is to test out electrochemical properties of this oxide, and to check their dependence on the substrate nature. For this, NiMoO4 powder is pressed into a 15 mm diametre disc. Thin films are subsequently grown on various substrates, such as kapton/Au sheets, Si (100), and BK7 glass slides, by using a KrF ns-pulsed UV laser. Results are presented and discussed mainly in terms of crystalline phase and crystallites dimensions, and corroborated to thin film roughness and their electrochemical behaviour.
Authors : A. Matei, R. Birjega, A. Trefilov, L. N. Dumitrescu, A. Lazea-Stoyanova, M.D.Ionita, A. Vlad
Affiliations : National Institute for Lasers, Plasma, and Radiation Physics, 409 Atomistilor Street, 077125 Magurele, Romania
Resume : The work proposed herein investigates the possibility of using clay thin films prepared by laser techniques as absorbents for heavy metals from aqueous solutions. Thin films of lamellar clays were deposited by laser techniques (matrix assisted pulsed laser evaporation (MAPLE), pulsed laser deposition (PLD)). The main property of these materials is the adsorption capability, which is connected to the layer charge density, cationic charge capacity and swelling characteristic. The considered clays were layered double hydroxides and montmorillonite. Aqueous solution of CuSO4 with different concentrations were used for the immersion of the films. Energy dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS) were the techniques employed to assess the copper uptake. Chemical, structural and morphological properties of the films were investigated before and after immersion for the identification of the adsorption mechanism taking place.
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Fundamentals of laser-mater interactions III : Peter SCHAAF
Authors : Martin Ehrhardt, Pierre Lorenz, Bing Han, Klaus Zimmer
Affiliations : Leibniz Institute of Surface Engineering (IOM), Leipzig 04318, Germany; Advanced Launching Co-innovation Center, Nanjing University of Science & Technology, Nanjing 210094, P.R. China
Resume : Ultra high precision machining of surfaces require gentle tools for high resolution, low-defect material removal at normal pressure that can be easily computer controlled. However, laser machining techniques still do not fulfill all requirements for such applications. Plasma processes enable high quality etching of various materials but require vacuum conditions. Laser and plasma processing are complementary technologies where each technology has its inherent advantages and shortcomings. In this presentation, a novel technology will be introduced which combines plasma and laser processing in order to make use of the advantages of both technologies. An ultra-short pulse laser source was used to generate a localized, free-standing micro plasma in a gas at atmospheric pressure by an optical breakdown. In order to modify, etch or deposit material, the plasma is brought in the proximity of a surface to allow the interaction of the species of the micro plasma with the surface. In particular, etching of fused silica and polyimide is discussed. These are reference materials etched by the laser-generated, reactive plasma that contains chemical species such as fluorine, chlorine or oxygen. In the presentation, the impact of selected parameters such as laser pulse energy, temperature, pressure, gas composition or plasma-surface distance on the etching rate and surface characteristics are shown. SEM, AFM, and XPS investigations reveal the achieved surface qualities and remarkable small chemical as well structural modifications.
Authors : Yudai Miyauchi1, Taiju Nakamura1, Kosuke Kawabata1, Tetsuo Ikari1, Takaaki Mano2, Takeshi Noda2 and Atsuhiko Fukuyama1
Affiliations : 1Faculty of Engineering, University of Miyazaki, 1-1 Gakuen Kibanadai-Nishi, Miyazaki 889-2192, Japan; 2National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, Japan
Resume : The temperature dependence of the luminescence properties is important for understanding the carrier dynamics of optoelectronic devices utilizing an ensemble of quantum dots (QD) such as lasers and solar cells. Photoluminescence (PL) spectroscopy is an effective methodology to investigate luminescence properties. On the temperature dependences of the PL peak energy in GaAs QD, the red-shift from the expected Varshni law around 100 K has been already observed. We recently observed an additional blue-shift in the higher temperature range above 150 K for the GaAs QD samples grown by droplet epitaxy. We have explained this behavior by a steady state rate equation model with presences of the size distribution of the QD as well as the carrier transition from the QD to the coupled excited states (CES). In this study, an excitation light intensity dependences of the PL peak energies were measured for confirming the usefulness of the steady state model. As a result, a reduction of the red-shift and an enhancement of the blue-shift were observed by increasing the excitation light intensity. The former reduction of the red-shift was well explained by supposing the carrier density in the CES increased by the strong excitation in our proposed model. However, the latter enhancement of the blue-shift could not be reproduced yet. This may be explained by an activation of other non-radiative centers due to the population of photo-excited carrier to higher energy states.
Authors : Orestis Marantos1, Vassilios Binas2, M. Moschogiannaki2, G. Kiriakidis1-2, D. Anglos2-3, Argyro Klini2
Affiliations : 1Department of Physics, University of Crete, P.O. Box 2208, GR 71003 Heraklion, Crete, Greece; 2Institute of Electronic Structure and Laser, Foundation for Research and Technology-Hellas (IESL-FORTH), P.O. Box 1385, GR 71110 Heraklion, Crete, Greece; 3Department of Chemistry, University of Crete, P.O. Box 2208, GR 71003 Heraklion, Crete, Greece
Resume : Semiconducting metal oxides are known to undergo changes in their properties electrical, optical, or mechanical in response to an external stimulus. This behavior makes oxide semiconductors highly promising materials for a number of chemical sensor applications and sensing schemes. In that context, new type of sensors based on the laser-induced photoluminescence (PL) emission of nanostructured materials (e.g. ZnO, CoTiO3, NiTiO3) and their capacity regarding their sensing properties will be presented [1,2]. Their sensing behavior has been investigated at different surrounding atmosphere (ethanol, oxygen) and temperature conditions (290-340 K), exploring both weak and strong laser excitation. For the optical characterization and the study of the PL emission the samples were optically pumped with laser sources of proper wavelength and pulse width (Nd:YAG laser, λ=355 nm, τ=8 ns; KrF laser, λ=248 nm, τ = 450 fs). The observed variability of PL indicators such as spectral intensity and width, offers a systematic way to monitor the environmental changes in a reliable manner, opening the path for exploiting oxide materials, as optical sensors even at remote distances or hostile environments. 1. A. Klini, M. Androulidaki, and D. Anglos, “Low Energy Pulsed Laser Excitation in UV Enhances the Gas Sensing Capacity of Photoluminescent ZnO Nanohybrids,” Sensors 19, 5490 (2019). 2. S. Murcia-López, M. Moschogiannaki, V. Binas, T. Andreu, P-Y. Tang, J. Arbiol, J. Jacas, G. Kiriakidis, J.R. Morante, “Insights into the Performance of (CoxNi1-x) Titanates as Photo- and Electro-Catalysts for Sun-Driven Water Oxidation,” ACS Applied Materials & Interfaces 9, 40290-40297 (2017).
Authors : Que R.*(1), Houel-Renault L.(2), Lancry M.(1), Fontaine-Aupart M.-A.(2), B. Poumellec(1) *lead presenter
Affiliations : (1) MAP/SP2M/ICMMO, Université Paris Saclay (CNRS), Orsay Cedex, France (2) CPBM/ISMO, Université Paris Saclay (CNRS), Orsay Cedex, France
Resume : Processes for spatially structuring the functional properties of organic materials involve structuring a deposit like lithography i.e. weak flexibility. Here, we show the creation of luminescence in organic compounds on the scale of a few microns using the special properties of the focused femtosecond laser (1030nm, 250fs, 0.6NA). We thus acquire the possibility in the field of organic photonics to spatially modify physical properties using a particular photochemistry. It is commonly thought that the femtosecond laser, because of its great intensity (power per unit area) can produce in organic materials only ablations. In fact, a delicate control of the parameters makes possible to access local chemical modifications that produce new molecules and therefore new physical properties, here a luminescence in the visible, for example. The material we use here for the demonstration is an amino acid. Some luminescence is created in a limited range of pulse energy and repetition rate. We observe two domains in the plan (pulse energy x repetition rate) where 2 kinds of chromophores are appearing, one with a short lifetime (0.4-0.7ns) and another one with a longer one (1.5-3.5ns). The luminescence spectrum is peaking at 560 nm under 488 nm excitation. The short lifetime chromophore is mainly created at low pulse energy (below 0.4 µJ/pulse for 1MHz) in the full volume of the focus and the large lifetime chromophore is rather appearing on the wall of the modified volume at higher energy.
Authors : Aanchal Agarwal, Yu-Sheng Huang, Ming-Yen Lu, Lih-Juann Chen
Affiliations : Department of Material Science and Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan
Resume : ZnO nanowires-based surface-plasmon-polariton (SPP) nanolasers with metal-insulator-semiconductor hierarchical nanostructure have emerged as potential candidates for integrated photonic applications. Herein, we demonstrated a SPP nanolaser consisting of ZnO nanowires coupled with single-crystalline aluminum (Al) film and WO3 insulating interlayer. High-quality ZnO nanowires have been prepared by using vapor phase transport and condensation deposition process via catalyzed growth. Subsequently, as prepared ZnO nanowires were transferred on a single-crystalline Al film grown by molecular beam epitaxy (MBE). Meanwhile, a WO3 dielectric interlayer has been deposited in-between of ZnO nanowires and Al film via e-beam technique for preventing the metallic region dominated optical loss. Such metal-oxide-semiconductor (MOS) structured SPP laser with optimal thickness of WO3 (3.6 nm) insulating layer demonstrates an ultralow threshold laser operation (lasing threshold of 0.79 MWcm-2). This threshold value is nearly 8-times lower as compared to that of previously reported similar ZnO/Al2O3/Al plasmonic lasers. Such suppression in lasing threshold is attributed to WO3 insulating layer mediated strong confinement of the optical field in the subwavelength regime.
Authors : Boubiche1 N., Abdesslam1 M., Zafeiratos3 S., Luo3 W., Speisser1 C., Muller1 D., F. Djeffal2 and F. Le Normand1,*
Affiliations : 1: MaCEPV/ICube, Université de Strasbourg and CNRS, STRASBOURG, 23 rue de Loess, BP 20CR, 67037 STRASBOURG, FRANCE. 2: Department Electronics, University of BATNA-1, 05000 BATNA, ALGERIA. 3 ICPESS, Université de Strasbourg and CNRS
Resume : We report on the preparation by Pulse Laser Deposition of DLC (ta-C) films on transparent quartz. Subsequently, minute amount (less than a monolayer) of transition metals (TM = Fe, Co, Ni) is deposited on these ta-C films (TM/ta-C/quartz sample) (1). Finally a thermocatalytic treatment is carried out to transform part or all the ta-C into a thin graphitic layer. Apart from the nature and the dose of metal evaporated, the thickness and the sp3/sp2 ratio, controlled by the PLD parameters (time and laser fluence), and the temperature and the nature of the gas treatment, were the key parameters investigated. The location of the metallic nanoparticles was investigated by XPS while the formation of graphitic domains was investigated by Raman spectroscopy. The choice of the transition metals has been operated as a function of their high reactivity to carbon-carbon bond with transition metals but also to their ability to absorb carbon. The system TM/thin graphitic layer/DLC/quartz exhibits under optimized conditions both high optical transmission and high surface electrical conductance, with figures of merit (conductivity of transparency) higher than ITO. We observed an optimum in the fluence as well as the thickness of the DLC layer. Ref : “Kinetics of graphitization of thin diamond-like carbon (DLC) films catalyzed by transition metal” N. Boubiche, J. El Hamouchi, J. Hulik, M. Abdesslam, C. Speisser, F. Djeffal and F. Le Normand, Diamond and Related Materials, 91 (2019) 190-198.
Laser processing of materials III : Catalin CONSTANTINESCU
Authors : R. Stoian
Affiliations : Laboratoire Hubert Curien, UMR CNRS 5516, Université de Lyon, Université Jean Monnet, 42000 St. Etienne, France
Resume : Nowadays micro/nano- technologies depend on processing tools able to structure materials in 2D and 3D with utmost precision. Ultrafast lasers can take up ambitious processing challenges where energy localization is critical. A limitation, intrinsic to optical methods, is related to diffraction, restricting irradiation to sizes comparable to the wavelength. However bypassing the diffraction limit is key for a new range of applications in optics and mechanics requiring access to the nanoscale. Possible solutions rely on material evolution in non-equilibrium conditions. Exploiting the nonlinearity of excitation and non-equilibrium, ultrashort laser pulses can show remarkable capacity to localize light on subwavelength scales, building up on collective carrier effects on surfaces and in the bulk. We will discuss here the capability of ultrafast laser to achieve structuring on 100 nm scales. We will show how control of laser interaction by beam spatio-temporal design, notably Gauss and Gauss-Bessel beams with engineered dispersion, can drive physical paths on smallest scales. One relevant application is related to photonics, notably the fabrication of optical devices based on laser-induced 3D refractive index engineering. Discussing the mechanisms of photoinscription we will follow the dynamics of electronic excitation in confinement conditions and point out characteristic times of energy deposition, serving as guidelines for high resolution. We pinpoint their potential to generate photonic systems where hybrid micro/nanoscale features can develop advanced optical functionalities.
Authors : Eva Nieto-Pinero (1), Nicolás Ramos(1,2), Jaime Martín(2), Esther Rebollar (3), Beatriz Galiana(4) and Rosalía Serna (1)
Affiliations : (1) Laser Processing Group, Instituto de Optica, IO,CSIC, Serrano 121, 28006 Madrid, Spain (2) POLYMAT, University of the Basque Country UPV/EHU, Avenida de Tolosa 72, 20018 Donostia-San Sebastián, Spain (3) Instituto de Química Física Rocasolano, IQFR,CSIC, Serrano 119, 28006, Madrid, Spain (4) Department of Physics, Escuela Politécnica Superior, Universidad Carlos III, 28911 Leganés, Madrid, Spain
Resume : Molybdenum oxides are versatile semiconductors whose optical and electronic properties depend strongly on their stoichiometry. In particular MoO3 is transparent and shows a wide bandgap (>3 eV) and a high dielectric constant k ~ 500. Additionally orthorhombic α-MoO_3 possesses the well-known layered crystal structure of MoO_3 which offers the possibility to create two dimensional (2D) morphologies. In this context, 2D MoO3 is an ideal material for electronic applications for high power electronics and short wavelength optoelectronics that materials with a wide band gap and high crystallinity in 2D limited thickness. In this contribution we show the successful preparation of thin films formed by 2D MoO3 crystals by a pulsed laser deposition based process that starts with the deposition of dense and continuous substoichimetric MoO_x films with thickness of few nm by PLD in vacuum from a MoO_3 target. Subsequently, the films are annealed in air up to 300ºC while following the evolution of their optical properties in-situ in the UV-VIS wavelength region by spectroscopic ellipsometry. When the temperature reaches 250ºC a clear change in the optical properties starts that is related to the films crystallization. Analysis of the optical properties shows how the initially absorbing films with a metallic-like behavior after the annealing become transparent in the NIR and VIS regions, and show a band gap >3 eV. Optical microscopy, AFM and electron microscopy show the formation of thin and large rectangular micron size α-MoO_3 single crystals; the structure and stoichiometry has been further confirmed by X-ray diffraction analysis, Raman and XPS spectroscopy. The full dielectric constant of α-MoO3 for the 2D crystals is reported for the first time and the implications for the optoelectronic applications will be discussed.//  I. A. de Castro, et al., Adv. Mater. 29, 1–31 (2017).  J-H Kim, et al., Nano Letters 19, 8868-8876 (2019)
Authors : Johannes Heitz (a), Cristina Plamadeala (a), Werner Baumgartner (b), Florian Hischen (b), Jaroslaw Jacak (c), Boris Buchroithner (c), Conor O’Mahony (d), Andrea Bocchino (d), Bettina Heise (e), Karoline Felbermayr (e)
Affiliations : (a) Institute of Applied Physics, Johannes Kepler University Linz, Austria; (b) Institute of Biomedical Mechatronics, Johannes Kepler University Linz, Austria; (c) University of Applied Sciences Upper Austria, Campus Linz, Austria; (d) Tyndall National Institute, University College Cork, Ireland; (e) Recendt GmbH, Linz, Austria
Resume : Laser-induced cones or spikes can be used for directional fluid transport if the irradiation is performed under an inclined angle We demonstrated this with KrF* excimer irradiated polyimide foils. Similar concepts are used in nature for instance by European true bugs, which transport defense liquids by inclined drop-like microstructures . The mechanism of the fluid transport is probably based on the spreading of the liquid film in the capillary channel around the drop-shaped microstructures which depend strongly on the curvation radius. We demonstrated also that this concept can be used for production of microneedles covered with drop-shaped microstructures for medical application, which transport a liquid passively to the needle tip . These microneedles were realized in polymeric photoresist by two-photon polymerization using a Ti:sapphire fs laser. The laser-written microneedles can be used as masters for replication processes. References:  Hischen F. et al., The external scent efferent system of selected European true bugs (Heteroptera): a biomimetic inspiration for passive, unidirectional fluid transport, Journal of Royal Society Interface (2018) 15, 20170975.  Plamadeala C. et al., Bio-inspired microneedle design for efficient drug/vaccine coating, Biomedical Microdevices (2020) 22, 8.
Authors : Camilo Florian (1), Jean-Luc Déziel (2), Sabrina V. Kirner (1), Jan Siegel (3), Jörn Bonse (1)
Affiliations : (1) Bundesanstalt für Materialforschung und -prüfung (BAM), Berlin, Germany; (2) Département de Physique, Université Laval, Québec, Canada; (3) Laser Processing Group, Instituto de Óptica IO-CSIC, Madrid, Spain
Resume : The formation of laser-induced periodic surface structures (LIPSS) in industrially relevant metallic, semiconducting, or ceramic materials usually takes place under atmospheric conditions. Since the laser-induced formation of superficial oxides changes the material’s optical response, this can influence the formation of LIPSS in all materials that are prone to oxidation. Hence, the in-depth understanding of the involved mechanisms becomes essential to exploit in full the capabilities of these structures for specific applications. In this work, we fabricate a new type of low spatial frequency LIPSS (LSFL) on the hard coating material chromium nitride using two different direct-write infrared femtosecond laser systems. Some resulting structures are unexpectedly parallel to the linear laser beam polarization used. Chemical, structural and morphological characterizations are performed on the irradiated samples using Raman spectroscopy, X-ray diffraction, atomic force microscopy and scanning electron microscopy respectively. The findings serve as input to finite-difference time-domain (FDTD) numerical simulations of the intensity distributions in an oxide film covered sample at different positions along the laser beam axis, suggesting that the parallel LSFL are formed at the sub-surface interface between the pristine sample material and a thin covering laser-induced oxide layer made of different graded oxide types.
Authors : Kanidi, M.(1,2), Kerasidou, A.P.(3), Tsamis, C.(3), Kandyla, M.*(1)
Affiliations : (1) Theoretical and Physical Chemistry Institute, National Hellenic Research Foundation, 48 Vasileos Constantinou Avenue, 11635 Athens, Greece (2) Department of Material Science, University of Patras, University Campus, 26504 Rio, Greece (3) Institute of Nanoscience and Nanotechnology, National Center for Scientific Research ‘Demokritos’, 15310 Athens, Greece
Resume : Large-area arrays of conical Si microstructures were developed by ns laser processing of Si in SF6 environment. ZnO nanorods were grown on micro-Si substrates via the hydrothermal method, varying the seeding layer concentration and growth time, which affect the nanorod morphology. The crystallinity, morphology, and topography of the surfaces were characterized by XRD, SEM, and EDS. We carried out water contact angle (CA) measurements on ZnO nanorods grown on micro-Si and on flat Si to study the wettability of the composite system. Laser structuring provides a large silicon specific area. ZnO nanorods are grown on the surface of the conical Si microstructures. After UV irradiation, ZnO nanorods grown on micro and flat Si present superhydrophilicity with similar CA values for both substrates. On the other hand, the functional surfaces switch reversibly to hydrophobicity after heating or dark storage, but ZnO nanorods grown on micro-Si present significantly higher CA values than those grown on flat Si. The hierarchical surfaces of ZnO nanorods on laser-microstructured Si substrates present a reversibly switching wettability, which is photosensitive and is related to the synergy of surface chemistry and surface micro/nanoroughness. Such functional surfaces are suitable for future applications of self-cleaning coatings, microfluidic devices, and antifogging materials, among others.
Authors : Sabri Alamri, Paul A. Sürmann, Tim Kunze
Affiliations : Fraunhofer-Institut für Werkstoff- und Strahltechnik IWS Winterbergstr. 28 01277 Dresden Germany
Resume : The processing of transparent materials by lasers oftentimes involves the use of high power ultraviolet sources or ultrashort pulsed laser in order to take advantage of non-linear absorption mechanisms for surface structuring. Moreover, applications such as decoration, wettability or antibacterial properties necessitate textures with sizes in the micro- or submicrometer range. In the last 10 years Direct Laser Interference Patterning (DLIP) has become increasingly important as a micromachining technique, thereby periodic microstructures can be generated by the coherent superposition of two or more laser beams. In the present work, glass (Soda Lime) has been textured through DLIP employing an ultrashort pulsed (10 ps) green (532 nm) laser source. The glass substrate, completely transparent at the given laser wavelength, could be selectively ablated. With a proper selection of the laser fluence dose, periodic dot-like and line-like structures with spatial periods ranging from 9 µm to 2.3 µm could be realized, employing two- and four-beam interference surface configurations. Highly homogenous structures can be obtained for both configurations, with structure depth of up to 1.2µm. The topography of the structured areas was investigated using optical confocal microscopy. The wettability behaviour of the textured surfaces has been also characterized by contact angle measurements, revealing a super-hydrophilicity for most of the treated samples. Moreover, tribological investigations revealed a decrease in the wear track for comparable measured friction coefficients.
Authors : A. Bellucci1, M. Mastellone1-2, M. Girolami1, V. Serpente1, V. Valentini1, E. Bolli3, A. Mezzi3, S. Kaciulis3, S. Orlando4, A. Santagata4, R. Polini1-5, E. Sani6, and D. M. Trucchi1
Affiliations : 1Istituto di Struttura della Materia (ISM-CNR), Via Salaria km 29.300, Monterotondo Scalo (RM), 00015, Italy; 2Dipartimento di Scienze di Base ed Applicate per l'Ingegneria, Università di Roma "La Sapienza", Via A. Scarpa 14, 00161, Roma, Italy; 3Istituto per lo Studio dei Materiali Nanostrutturati (ISMN-CNR), Via Salaria km 29.300, Monterotondo Scalo (RM), 00015, Italy; 4Istituto di Struttura della Materia (ISM-CNR), Contrada Santa Loja, Tito Scalo (PZ), 85050, Italy; 5Dipartimento di Scienze e Tecnologie Chimiche, Università di Roma “Tor Vergata”, Via della Ricerca Scientifica 1, Rome, 00133, Italy; 6Istituto Nazionale di Ottica (INO-CNR), Largo E. Fermi, 6 Firenze (FI), I-50125, Italy.
Resume : Double fs-pulse experiments were performed on the overall surface of different semiconductors (Si, InP, SiC, diamond) to finely control their optical properties inducing 2D-nanostructured morphologies. By tuning both the pulse delay and polarization of the incident laser beams, the formation of regular laser-induced periodic surface structures (LIPSS) able to attribute the desired properties of absorption and selectivity to the semiconductor, have been observed. The configuration employed for the double-fs-laser pulse (Ti:Sapphire, 800 nm) sequences was collinear and both beams were focused, by both 4x and 40x microscope objective, on the sample surface that was moved, according to a raster path, in order to fully treat it. The inter-pulse delay of the individual 100-fs-duration pulses was varied from 50 fs up to 30 ps, whereas the double pulse laser beam vertical and horizontal polarizations were combined each other. In order to guarantee the most proper dose of laser beams impinging on the sample surface, this was moved continuously with speeds ranging from 0.1 to 5 mm/s under the laser repetition rate of 1 kHz. The resulting treated samples were analyzed by scanning electron microscopy, Raman, XPS, UV-visible-IR spectroscopy to finely tune the treatment parameters for each different semiconductor. The obtained results allow a clear identification of the advantages connected to the double-pulse treatment with respect to the single pulse irradiation. The effectiveness of the double-fs-pulse used in the present work in controlling the resulting nanometer 2D-textures of the samples’ surface and, as a consequence, the semiconductors’ optical absorption and selectivity is thus provided.
Authors : Mario Garcia-Lechuga, Andong Wang, Amlan Das, Olivier Utéza, Nicolas Sanner, David Grojo
Affiliations : Aix-Marseille Univ., CNRS, LP3 UMR7341, 13009 Marseille
Resume : We study femtosecond laser interactions in various bandgap materials at non-conventional driving wavelengths from the deep-ultraviolet to the mid-infrared part of the spectrum. The range of nonlinear responses accessible by radiation tuning allow to revisit questions as important as the achievable resolution in laser machining technologies. In particular, we establish that the concept of nonlinear resolution is not applicable for femtosecond laser ablation. Independently of the nonlinearity of interaction, we find a systematic one-to-one mapping between femtosecond laser ablation features in dielectrics and beam contours at a strict threshold-intensity. This is because any observable based on threshold-based response (as ablation) simply ruins all potential benefits that could be expected on resolution from the nonlinear confinement of absorption. Accordingly, the use of extreme UV should not be overlooked to reach the nanoscale resolutions routinely achieved in lithography. At the opposite side of the spectrum, ultrashort infrared laser pulses open opportunities to tailor in the three dimensions (3D) some semiconductors inside which breakdown regimes were inaccessible until recent demonstrations. Our first proposed solution uses hyper-focused beams to demonstrate permanent modifications in the bulk of silicon with sub-100-fs. For more practical alternatives, we rely on optimizations in the time domain. We generate and apply ultrafast trains of pulses at the highest achievable repetition-rates (up to THz). This introduces unique multi-timescale control parameters used for improved energy deposition and reliable 3D laser writing deep inside silicon chips.
Poster 2 : Martin EHRHARDT, Florence GARRELIE, Peter SCHAAF and co-chairs
Authors : Naoufel Khemiri, M. Kanzari
Affiliations : Université Tunis El Manar, Institut Préparatoire aux Etudes d’Ingénieurs El Manar, Campus Universitaire Farhat Hached, B.P 244, Tunis 2092, Tunisie. Université Tunis El Manar, Ecole Nationale d’Ingénieurs de Tunis, Laboratoire de Photovoltaïque et Matériaux Semi-conducteurs, B.P 37, 1002,Le Belvédère Tunis, Tunisie. Université de Tunis, IPEITunis Montfleury, Laboratoire de Photovoltaïques et Matériaux Semi-conducteurs-ENIT.
Resume : Tin antimony sulfide Sn-Sb-S (TAS) is one of the most promising compounds for the next generation of optoelectronic and thin film photovoltaic devices. TAS material was synthesized by a solid-state reaction using earth-abundant tin, antimony and sulfur elements. The effects of excimer laser annealing (ELA) at different pulse energies on the structural, morphological and optical properties of thermally evaporated TAS films were investigated. X-ray diffraction (XRD), scanning electron microscopy (SEM) and Raman spectroscopy measurements showed that the films annealed by an excimer laser of 248 nm were amorphous for weak energy densities whereas the sample irradiated with 111 mJ/cm-2 was polycrystalline with a preferential orientation. The ELA effects on the optical properties were also studied in the wavelength range 300-1800 nm by using UV-Vis-NIR spectroscopy. The absorption coefficient of all samples in the fundamental absorption region is higher than 104 cm-1. We also found that the optical band gap decreases from 2.04 to 1.84 eV after irradiating the thin films under different laser energy densities.
Authors : M. Socol1*, N. Preda1, C. Breazu1, A. Costas1, G. Petre1, A. Stanculescu1, G. Popescu-Pelin2, G. Socol2
Affiliations : 1National Institute of Material Physics, 405A Atomistilor Street, 077125, Magurele, Romania 2National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Street, 077125, Magurele, Romania
Resume : Matrix Assisted Pulsed Laser Evaporation (MAPLE) technique was used to obtain blended thin films based on poly(N-alkyldiketopyrrolo-pyrrole dithienylthieno[3,2- b ]thiophene) (DPP-DTT) and fullerene C60. DPP-DTT is a low band gap polymer (1.7 eV) featured by a high mobility and stability used in the various fields such as photovoltaic cells, OFETs, etc. MAPLE is usually involved in the preparation of organic semiconductor films taking into account that the chemical structures of the raw materials are not affected by the laser beam and the thickness of the obtained films are controlled during the deposition. Thus, organic layers based on DPP-DTT and C60 in different weight ratios were deposited by MAPLE using chloroform as solvent and a low laser fluence. A throughout characterization of the MAPLE films was made for evidencing the influence of the ratio between the two organic components on their optical and electrical properties. The optical features of the DPP-DTT are identified in the UV-VIS and photoluminescence (PL) spectra of the MAPLE films. The vibration fingerprints of the raw materials were observed in the infrared (IR) spectra of the deposited organic films. The scanning electron microscopy (SEM) and atomic force microscopy (AFM) images revealed the globular morphology characteristic to the films deposited by MAPLE. The current-voltage (I-V) characteristics of the fabricated blended structures recorded in dark and under illumination show that their electrical parameters are strongly related by the DPP-DTT:C60 ratio. The results proved that using MAPLE as deposition technique blended organic thin films based on DPP-DTT and C60 with tuned electrical properties can be prepared, these being further integrated in organic devices for different applications.
Authors : A. I. Kostyukov *(1),(4), V. N. Snytnikov (1),(2), M. I. Rakhmanova (1),(3), N.Y. Kostyukova (1),(4),(5), M.S. Molokeev (6),(7),(8), A.S. Krylov (6), and A.S. Aleksandrovsky (6),(7)
Affiliations : (1) Novosibirsk State University, Pirogova Str. 2, 630090, Novosibirsk, Russia; (2) Boreskov Institute of Catalysis SB RAS, Lavrentieva Ave. 5, 630090, Novosibirsk, Russia; (3) Nikolaev Institute of Inorganic Chemistry SB RAS, Akad. Lavrentiev Ave. 3, 630090, Novosibirsk, Russia; (4) Institute of Laser Physics SB RAS, Lavrentyev Ave. 15b, 630090, Novosibirsk, Russia; (5) Novosibirsk State Technical University, K. Marx Ave. 20, 630073 Novosibirsk, Russia; (6) Kirensky Institute of Physics Federal Research Center KSC SB RAS, Krasnoyarsk 660036, Russia; (7) Siberian Federal University, Krasnoyarsk, 660041, Russia; (8) Department of Physics, Far Eastern State Transport University, Khabarovsk, 680021, Russia; * lead presenter
Resume : Investigations of new red phosphors are presently extremely abundant area of materials research. Synthesis of Y2O3 nanoparticles with monoclinic structure is still a challenging task. In this work, Eu:Y2O3 nanoparticles were obtained via cw CO2-laser vaporization with subsequent condensation of vapor in a buffer Ar gas flow (0.1 and 0.5 atm) in a vaporization chamber. XRD analysis shows that laser vaporization enables crystallization of Y2O3 in the crystal structure belonging to monoclinic symmetry class (C2/m space group). HRTEM evidences formation of high crystallinity spherical nanoparticles with the particle sizes dm~10 nm (0.1 atm of Ar) and 15 nm (0.5 atm of Ar). PL spectrum in the vicinity of 5D0→7F0 transition demonstrates three peaks consistent with three inequivalent positions of Eu3+ ion in m-Y2O3 lattice. 5D0→7F2 transition dominates in the spectrum, admitting the lack of inversion symmetry at Cs sites occupied by Eu3+. The spectrum is expanded to the red part of spectrum due to intense transitions terminating at higher-lying components of crystal-field-split 7F2 energy level. Obtaining chromaticity coordinates (0.669, 0.331) is possible using red phosphor based on m-Y2O3:Eu3+. Current investigation revealed unique possibility of crystal field shaping of Eu3+ PL spectrum in a polymorph of Y2O3 which will result in high color purity and meets technology needs in a number of wLED applications. This work is financially supported by the RFBR № 19-32-60027.
Authors : Dmitrii V. Shuleiko (1), Mikhail N. Martyshov (1), Dmitrii V. Amasev (1), Andrey G. Kazanskii (1), Stanislav V. Zabotnov (1), Denis E. Presnov (2,1), Pavel K. Kashkarov (1)
Affiliations : (1) Lomonosov Moscow State University, Faculty of Physics, 1/2 Leninskie Gory, Moscow, 119991, Russia; (2) Lomonosov Moscow State University, Skobeltsyn Institute of Nuclear Physics, 1/2 Leninskie Gory, Moscow, 119991, Russia
Resume : Amorphous hydrogenated silicon (a-Si:H) attracts scientific interest for thin-film photovoltaics. Femtosecond laser nanocrystallization can improve such a-Si:H solar cells. For example, degradation of a-Si:H electrical properties under sunlight (Staebler-Wronski effect) can be minimized. Also femtosecond laser modification can lead to formation of laser-induced periodic surface structures (LIPSS) on a-Si:H, which induce optical and electrical anisotropy  and can be used in optoelectronic applications. In this work we investigated anisotropy of structural, electrical and photoelectrical properties of a-Si:H films modified by femtosecond laser pulses in raster mode. On the modified surface we observed various LIPSS types formation, with parallel or perpendicular orientation relative to laser polarization. Electrical measurements showed that dark conductivity of modified films increased due to formation of silicon nanocrystals by femtosecond laser pulses. According to Raman spectroscopy nanocrystalline phase volume fraction was up to 30%. Also, anisotropy of dark conductivity and mobility of charge carriers was observed in the a-Si:H films after femtosecond laser irradiation. This can be explained by LIPSS depolarizing effect and non-uniform film crystallization both within raster lines and LIPSS. The work was supported by the Russian Foundation for Basic Research (project 19-32-70026).  Shuleiko D. V., Potemkin F. V., Romanov I. A., et al. Laser Phys. Lett. 15:056001 (2018)
Authors : N.Nedyalkov1, M.E. Koleva1, N.E. Stankova1, R. Nikov1, E. Iordanova2, G. Yankov2, L. Aleksandrov3, R. Iordanova3
Affiliations : 1Institute of Electronics, Bulgarian Academy of Sciences, Tzarigradsko shousse 72, Sofia 1784, Bulgaria; 2Institute of Solid State Physics, Bulgarian Academy of Sciences, 72 Tzarigradsko Chaussee, 1784, Bulgaria; 3Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, Acad. Georgi Bonchev str. bld.11, 1113 Sofia, Bulgaria;
Resume : In this work results on laser assisted formation of gold and silver nanoparticles in glass are presented. The sample material is Au/Ag-doped borosilicate glass obtained by conventional melt quenching method. The produced glass samples are irradiated by nanosecond and femtosecond laser pulses with a wide variety of parameters – wavelength, fluence, and applied pulse number. At certain conditions both nanosecond and femtosecond laser radiation induces formation of yellow colored areas in the material. The transmission spectra and TEM analysis indicate formation of Ag nanoparticles in the irradiated zones. After annealing of the samples, the irradiated areas lose their yellow coloration, and express red color whit clear dip in the transmission spectra. This effect is related to decomposition of the initially formed Ag nanoparticles and formation of gold nanoparticles and their optical properties defined by plasmon resonance. The optical properties of the irradiated areas for the both regimes are found to depend on the laser processing parameters. These dependencies, the mechanism of nanoparticle dynamics, and the possibility of formation of composite Au-Ag nanoparticles are discussed. This method can be used in fabrication of 3D nanoparticles systems in transparent materials that can be applied in the design of new optical components as metamaterials and in plasmonics.
Authors : Oleksandr Semchuk, Oleksandr Havryliuk, Anatoliy Biliuk
Affiliations : Chuiko Institute of Surface Chemistry National Academy of Sciences of Ukraine
Resume : Metal nanostructures and nanocomposites based on metal nanoparticles embedded into dielectric matrices are currently objects of extensive research thanks to its properties. Of the greatest interest of which are phenomena associated with plasmon resonance. Plasmons, which are collective vibrations of electrons, arise when the metal-insulator or semiconductor-insulator interfaces are irradiated by a laser of a certain (resonant) wavelength (frequency). The existence of localized plasmons is due to the resonant excitation of electrons in metal nanoparticles, which manifests itself in resonant absorption and scattering of electromagnetic waves, the formation of strong electric fields near the nanoparticles and related effects. In this paper, we propose a theory of this phenomenon based on the kinetic equation method. The kinetic equation method is used to study the peculiarities of electron interactions with the surface of a spheroidal metal nanoparticle when the electron scattering from the particle surface becomes a dominant effect. The frequency dependencies of the components of the electric conductivity tensor were found, and their dependence on the spheroidal aspect ratio was investigated. We predict the surface plasmon line width in metal nanoparticles with varying the dielectric constant of an embedding medium.
Authors : P.C. Peng (a,b), Y.C. Wu (c), Y.L. Su (b), X.H. Guo (d) and C.N. Kuo (a,b,*)
Affiliations : a. Department of Bioinformatics and Medical Engineering, Asia University, Taichung, Taiwan b. 3D Printing Medical Research Institute, Asia University, Taichung, Taiwan c. Department of Materials and Optoelectronic Science, National Sun Yat-Sen University, Kaohsiung, Taiwan d. Casting Technology Section, Metal Processing R&D Department, Metal Industries Research & Development Centre (MIRDC), Kaohsiung, Taiwan
Resume : In our understanding, aluminum alloys exhibit the characteristics of light weight, good formability, good specific strength, good corrosion resistance and recyclability. According to the material nature, aluminum alloys are widely applied in aerospace, construction, automotive, and medical applications. In point of view of the lightweight, the specific strength of traditional aluminum alloys is usually lower than that of titanium alloys. Hence, global researchers have done their efforts to develop advanced aluminum alloys with higher specific strength to further increase the degree of lightweight. Therefore, the Scalmalloy with a higher specific strength than traditional aluminum alloys were developed. The scandium is an extremely effective grain refiner for the aluminum alloy, which causes a significant change in the microstructure and properties of aluminum alloys. However, because it’s strength is higher than that of traditional aluminum alloys, it is more difficult to be shaped up or deformed through traditional processes. In this study, selective laser melting (SLM) process was introduced for sample manufacturing. Meanwhile, since different cooling rate/thermal history from the surface into the melting pool may cause different size/distribution of precipitates during the 3D printing process. This study is aimed at the development the heat treatment parameters of Al-Sc alloy after the 3D printing to unify the size/distribution or the precipitates. Thus, the microstructure analysis (such as TEM, XRD, EBSD, etc.) and tensile tests would be conducted and examined carefully to evaluate the optimized heat treatment parameters.
Authors : Y.P. Wang (a,b), Y.C. Wu (c), Y.L. Su (b), X.H. Guo (d) and C.N. Kuo (a,b,*)
Affiliations : a. Department of Bioinformatics and Medical Engineering, Asia University, Taichung, Taiwan b. 3D Printing Medical Research Institute, Asia University, Taichung, Taiwan c. Department of Materials and Optoelectronic Science, National Sun Yat-Sen University, Kaohsiung, Taiwan d. Casting Technology Section, Metal Processing R&D Department, Metal Industries Research & Development Centre (MIRDC), Kaohsiung, Taiwan
Resume : In recent years, 3D printing technologies have been applied widely, and lots of medical devices such as implants were fabricated by 3D printing technologies. Due to the needs of customization, the shape of the implants were mostly made in irregular to fit the shape of reconstruct joint/bone. Besides, in order to improve the bone ingrowth into the implants, the porous structure were usually introduced. On the other hand, in terms of mechanical property, the rougher surfaces on the surface of struts would cause stress concentration which would decrease strength, ductility, and fatigue life of porous materials. Moreover, in previous studies, rough surfaces may cause mechanical degradation due to stress concentration effects, and the relationship between surface roughness and strut diameter can affect the work of fracture. According to the shape of porous structure, the design biomedical materials is mostly complicated and the pore size of porous structure is only several hundred micrometers. Therefore, the surface treatments are very hard to be achieved by traditional method such as tool machining. However, the strut of the porous samples fabricated with 3D printing exhibit rough surfaces with some manufacturing imperfections. Hence, global researchers have done lots of efforts on the post treatment of 3D printed samples to improve surface roughness. Among the post process methods, electropolish is much more promising to deal with such irregular porous materials. In this study, titanium alloy (Ti64) which is widely used as biomedical materials was printed by using Selective Laser Melting (SLM) technology. The surface roughness of the printed porous samples was modified by electropolishing. The impact of surface roughness on mechanical properties was examined in terms of work of fracture through compression testing.
Authors : T. Y. Hsu (a,b), K. Y. Chen (a,b), Y. N. Ding (c), X.H. Guo (d) and C.N. Kuo (a,b,*)
Affiliations : a. Department of Bioinformatics and Medical Engineering, Asia University, Taichung, Taiwan b. 3D Printing Medical Research Institute, Asia University, Taichung, Taiwan c. 3D Printing Medical Research Center, China Medical University Hospital, Taichung, Taiwan d. Casting Technology Section, Metal Processing R&D Department, Metal Industries Research & Development Centre (MIRDC), Kaohsiung, Taiwan
Resume : Nowadays, more and more biomedical materials are applied in human body. Among the materials, Ti-6Al-4V are the most common used metal biomaterials due to the outstanding biocompatibility. However, Alzheimer disease may be caused by aluminum ions and carcinoma of gallbladder may be caused by vanadium ions released into human body. Because of that, developing toxic free biomaterials becomes an important issue, hence, Titanium-Tantalum alloy is developed to replace such as Ti-6Al-4V and other materials. Moreover, due to the advantage of porous structure, such as the improvement of bone integration and controllable mechanical properties, more and more porous implants are made by 3D printing technology. In this study, the aim is to prove the biocompatibilities of 3D printed Ti-Ta samples are equal to the parts made by the Ti-6Al-4V powders produced at brand of Renishaw(UK) and Circle(TW) to identify the medical used potential of 3D printed Ti-Ta alloy. To clarify the survival rate of the cells, L929 cells were used and cultured with the medium that soaked metal powders before experiments. After that, survival rate of the cells which were cultured for one day and three days was observed by MTT assay. Furthermore, cells were cultured on the surface of Ti-Ta and Ti-6Al-4V samples which printed by selective laser melting (SLM) technology to analyze adhesion rate.
Authors : R.Pascu, A. Matei, B.Sava, R.Birjega, A. Lazea Stoianova, A. Trefilov
Affiliations : NATIONAL INSTITUTE FOR LASER PLASMA AND RADIATION P.O. BOX MG 07, 077125 M?GURELE, ROMANIA
Resume : Cubic fluorite structures of 20Ni-SDC/8YSZ thin films are deposited on Pulsed laser Deposition (PLD) at 500?C and 600?C, at different number of pulses (90.000 pulses for 8YSZ and 36.000 pulses for 20 Ni-SDC) like anode for µSofc and reference electrode for potentiometric oxygen sensor on different substrates (Si(100) and Ti). Dense 8YSZ thin film is used like substrate for Ni-YSZ anode; electrochemical measurements are used to determine polarization resistance and overpotentional like a function of current density. The structural and optical characterization by XRD, AFM, SEM, XPS and SE indicate crack free structures with good adhesion. Keywords: Ceramic thin films, 20Ni-SDC/8YSZ, PLD, Cubic Fluorite Structure, Electrochemical devices.
Authors : Adrian Olejnik (1)*, Jakub Karczewski (2), Katarzyna Siuzdak (1), Katarzyna Grochowska (1)
Affiliations : (1) Centre for Plasma and Laser Engineering, Polish Academy of Sciences, 14 Fiszera st., 80-231 Gda?sk, Poland; (2) Faculty of Applied Physics and Mathematics, Gda?sk University of Technology, 11/12 Narutowicza st., 80-233 Gda?sk, Poland
Resume : Due to the rising problem of diabetes as well as the increasing number of people monitoring glucose level during exercises, new developments in the field of glucose sensing are needed. Among different sensors, electrochemical ones seem to be of a particular interest, as they are highly reliable and sensitive. In our studies, we propose the active element of such sensor that is based on structured titanium foil covered with Au nanoparticles, which are formed out of ultra-thin metallic layers by means of nanosecond laser dewetting that can be easily scaled up. Application of different laser working parameters (?: 266, 355, 532 nm; fluencies: 15-90 mJ/cm2) enables to obtain a variety of gold nanoparticles configurations confirmed by scanning electron microscopy inspection. Proper optimization of these parameters lead to formation of Au-Ti structures that are characterized by twice as better response than furnace dewetted Au nanoparticles over Ti structured foil . Moreover, the selectivity and mechanical stability of prepared material is maintained. Electrochemical tests in the presence of human serum as well as in artificial sweat and saliva were performed to verify the possible application of electrodes in the real conditions. Obtained results confirmed that fabricated material may be beneficial in future commercial devices. Research is financed by NCBR via LIDER/2/0003/L-8/16/NCBR/2017 grant.  Olejnik et al. Electroanalysis 31 (2019) 10.1002/elan.201900455
Authors : A. Og. Dikovska, G. Atanasova, T. Dilova, Ru. G. Nikov, N. N. Nedyalkov
Affiliations : A. Og. Dikovska - Institute of Electronics, Bulgarian Academy of Sciences, 72 Tsarigradsko Chaussee, Sofia 1784, Bulgaria; G. Atanasova - Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev str., bl. 11, 1113 Sofia, Bulgaria; T. Dilova - Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, аcad. G. Bonchev str., bl. 11, 1113 Sofia, Bulgaria; Ru. G. Nikov - Institute of Electronics, Bulgarian Academy of Sciences, 72 Tsarigradsko Chaussee, Sofia 1784, Bulgaria; N. N. Nedyalkov - Institute of Electronics, Bulgarian Academy of Sciences, 72 Tsarigradsko Chaussee, Sofia 1784, Bulgaria
Resume : Semiconductor oxides are among the most widely studied materials in view of gas sensor application due to their remarkable physical, optical and optoelectronic properties. One novel approach to modifying and improving the performance of a semiconductor oxide as gas sensing material is forming a composite with other semiconductor oxides, i.e. combining the advantages of both components into a single composite material. Another approach to improving the gas sensing performance of these materials is producing a nanostructured morphology to increase the surface area. An efficient way of overcoming the higher operating temperature as a disadvantage of the metal-oxide sensors is illuminating their surface by ultraviolet or visible light. In this work, we report fabrication of highly porous metal-oxide nanocomposites by pulsed laser deposition performed in air at atmospheric pressure. The technology applied leads to formation of nanostructures composed of nanoparticles. The attention was focused on the structure, morphology, composition, and optical properties of ZnO-TiO2 metal oxides. Results on the gas-sensing properties of the nanostructures with different composition are reported. The effect was investigated of the light irradiation on the response and time of response and recovery of the sensor elements. The gas sensing properties of the samples were compared under light irradiation at different wavelengths.
Authors : Ru.G. Nikov, A.Og. Dikovska, G.V. Avdeev, G.B. Atanasova, N.N. Nedyalkov
Affiliations : Ru.G. Nikov - Institute of Electronics, Bulgarian Academy of Sciences 72 Tsarigradsko Chaussee, 1784 Sofia, Bulgaria; A.Og. Dikovska - Institute of Electronics, Bulgarian Academy of Sciences 72 Tsarigradsko Chaussee, 1784 Sofia, Bulgaria; G.V. Avdeev - Rostislaw Kaischew Institute of Physical Chemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev str., Bl.11, 1113 Sofia, Bulgaria; G.B. Atanasova - Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev str., bl. 11, 1113 Sofia, Bulgaria; N.N. Nedyalkov - Institute of Electronics, Bulgarian Academy of Sciences 72 Tsarigradsko Chaussee, 1784 Sofia, Bulgaria
Resume : Recently, the focus of investigations in the field of nanoscience and nanotechnology is in designing nanomaterials that integrate two distinct functionalities into a single unit; for example, systems consisting of a magnetic material and metal-oxide semiconductor. This paper presents experimental results on fabrication of hybrid nanostructures composed by magnetic and metal-oxide nanoparticles. The samples are produced by a single-step process of pulsed laser deposition carried out in air at atmospheric pressure. One part of the depositions is performed by laser ablation of two metal or metal oxides targets: Fe–Zn, Fe–Ti and Fe2O3–ZnO, Fe2O3–TiO2. Other part of the experiments includes depositions from mixed targets of iron oxide and ZnO as well as iron oxide and TiO2 with different ratio between the target materials. Depositions are also performed in a magnetic field in order to control the morphology of the hybrid nanostructures. The laser ablation is carried out by nanosecond laser pulses delivered from Nd:YAG laser system working at its fundamental wavelength of 1064 nm. The structure, morphology and optical properties of the obtained structures are studied in relation to the sample’s composition. An analysis on the magnetic properties of the hybrid structures is also performed. The obtained nanostructures could be used in the design of novel magneto-optics and sensor devices.
Authors : Valentina Dinca1, Qian Liu2,#, Anca Bonciu1,3, Rusen Laurentiu1, Nicoleta Dumitrescu1, Antoniu Moldovan1 and Cerasela Zoica Dinu2
Affiliations : 1National Institute for Lasers, Plasma and Radiation Physics, Atomistilor 409, Magurele, Bucharest, 077125, Romania 2Department of Chemical and Biomedical Engineering, West Virginia University, Morgantown, WV, 20508, USA 3University of Bucharest, Faculty of Physics, Magurele, 077125, Romania
Resume : Thin films of electrochromic (EC) materials are being considered for energy saving platforms. However, manufacturing high quality EC films, of superior stability and high coloration efficiency available and persistent in diverse conditions of temperature and/or illumination is challenging. Herein we proposed to create the next generation of EC hybrid thin films with controlled thickness and uniformity. Our model system incorporates tungsten trioxide and graphene and uses a Matrix Assisted Pulsed Laser Evaporation (MAPLE) method for the proposed controlled synthesis. The obtained hybrid thin films were characterized for their chemical and physical properties using Fourier Transform Infrared and energy dispersive spectroscopy, X-Ray diffraction, and optical and atomic microscopy respectively, while changes in their electrochemical characteristics were evaluated using cyclic voltammetry. It was found that hybrid films characteristics could be controlled by the MAPLE deposition conditions. It was also found that the obtained films have enhanced electron transport capabilities thus possibly providing lower resistance pathways at their interfaces. It is expected that our work could provide a user-controlled synthesis and manufacturing strategy to lead to thin films formation that have minimum interfacial defects while possessing maximum conversion efficiency to influence and/or dictate the energy saving profile of EC materials.
Authors : Laurentiu Rusen1, Madalina Icriverzi2, Livia Elena Sima2, Antoniu Modovan1, Anca Bonciu1,3, Anca Roseanu2 and Valentina Dinca1
Affiliations : 1 National Institute for Lasers, Plasma and Radiation Physics, Atomistilor 409, 077125, Magurele, Bucharest, Romania 2 Institute of Biochemistry, Romanian Academy, 296 Splaiul Independentei, Bucharest, Romania 3 University of Bucharest, Faculty of Physics, RO–077125, Magurele, Romania Corresponding authors: firstname.lastname@example.org
Resume : In this work, poly(N-isopropylacrylamide) (pNIPAM) derivatives (amine, azide and amide terminated pNIPAM) termoresponsive coatings were studied and correlated to MSCs behaviour. The surface properties of pNIPAM based coatings, especially their hydrophobic/hydrophilic character, as well as the thermoresponsive capacity were tuned by strict control over MAPLE parameters depositions and target composition. The chemical functionality was kept for all the samples obtained by MAPLE and the thermoresponse was demonstrated by the change in the contact angle and thickness values when the temperature was shifted from 37°C to 24°C for all the materials tested, with a smaller change for maleimide terminated pNIPAM. Biological assays performed in vitro (fluorescence microscopy and Scanning Electron Microscopy (SEM)) confirmed the conditioning of the early mesenchymal stem cell (MSC) growth by specific chemistry of the coatings. The cell imaging analysis revealed no cytotoxic effect of pNIPAM surfaces irrespective of type of functionalization.
Authors : Patricia Maldonado Altamirano, Luis Arturo Martínez Ara, Ma. de los Ángeles Hernández Pérez, Jaime Santoyo Salazar, Jorge R. Aguilar Hernández, Máximo López López
Affiliations : Programa de Nanociencias y Nanotecnología, CINVESTAV- Instituto Politécnico Nacional, Av. Instituto Politécnico Nacional 2508, Gustavo A. Madero, San Pedro Zacatenco, 07360 Ciudad de México, CDMX; ESFM- Instituto Politécnico Nacional, Edif. 9, IPN, U.P.A.L.M., Col. Lindavista. C.P. 07738, CDMX; ESIQIE-Instituto Politécnico Nacional, Edif. 8, IPN, U.P.A.L.M., Col. Lindavista. C.P. 07738, CDMX; Depertamento de Física, CINVESTAV- Instituto Politécnico Nacional, Av. Instituto Politécnico Nacional 2508, Gustavo A. Madero, San Pedro Zacatenco, 07360 Ciudad de México, CDMX; ESFM- Instituto Politécnico Nacional, Edif. 9, IPN, U.P.A.L.M., Col. Lindavista. C.P. 07738, CDMX; Depertamento de Física, CINVESTAV- Instituto Politécnico Nacional, Av. Instituto Politécnico Nacional 2508, Gustavo A. Madero, San Pedro Zacatenco, 07360 Ciudad de México, CDMX
Resume : In this work, we present some results and analysis concerning the processing of semiconducting CdSe nanoparticles obtained by laser ablation of diluted CdSe powder in acetone. An Nd-YAG pulsed laser was used for ablation, tuned at the first and second harmonic, λ=1064 and 532 nm, 50 Hz frequency repetition for 30 minutes. The experiment was performed at different power intensities. An important difference in the size of the samples synthesized at 1064 nm and 532 nm is observed, being 12 nm for the samples processed with the infrared line and less than 5 nm for those processed with the green line. The emission and absorption of the samples run from 1.8 to almost 2.4eV for the smallest particles; in addition to this, by Raman spectroscopy, it is possible to differentiate between surface mode phonon and longitudinal optic phonon in samples synthesized at 532nm. A complete characterization by UV-Vis Absorption, Photoluminescence, Raman, Energy Dispersive Spectroscopy, Transmission Electron Microscopy, and X-Ray Diffraction is presented and analyzed
Authors : Breazu, C.(1*), Socol, M.(1), Rasoga, O.(1), Preda, N.(1), Catargiu, A-M.(2), Popescu-Pelin, G.(3), Socol, G.(3), Mihailescu, A.(3), Stanculescu, A.(1).
Affiliations : (1) National Institute of Materials Physics, 405A Atomistilor Street, P.O. Box MG-7, Magurele, 077125 Romania, email@example.com (2) Petru Poni Institute of Macromolecular Chemistry, 41 A Gr. Ghica Voda Alley, 700487, Iasi, Romania (3) National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Street, 077125, Magurele, Romania
Resume : Nowadays, the development of organic photovoltaics cells (OPV) with high efficiency is an interesting research challenge. Generally, the performance of OPVs are related to the materials, design and/or manufacturing process. A limitation is caused by the fact that many more organic compounds show p-type than n-type conduction. Usually, due to its high mobility, the fullerene C60 was utilized as electron transport material in the OPVs. However, taking into account its low solubility, many attempts were made to replace C60 with non-fullerene compounds. Thus, in the present study, bulk heterojunctions thin films based on perylene tetracarbxidiimide (PT) derivative compound as acceptor and zinc phtalocyanine (ZnPc) as donor were deposited by Matrix Assisted Pulsed Laser Evaporation (MAPLE) technique. In order to select the films with the best properties, the mixed active layers have been prepared using various ratios between the two organic components. The deposited MAPLE layers were investigated from structural, morphological, optical and electrical point of view using X-ray diffraction, scanning electron microscopy, atomic force microscopy, UV-Vis spectroscopy, photoluminescence spectroscopy and I-V measurements, respectively. The results emphasized that such organic heterostructures prepared by MAPLE technique can be integrated in photovoltaic devices.
Authors : Javier Prada(1,2), Pablo Moreno(1), Esther Rebollar(2).
Affiliations : 1Grupo de Aplicaciones del Láser y Fotónica (ALF-USAL), Universidad de Salamanca, Pl. de la Merced s/n, 37008 Salamanca, Spain; 2Instituto de Química Física Rocasolano (IQFR-CSIC), C/Serrano 119, 28006 Madrid, Spain.
Resume : Fs-Laser Induced Periodic Surface Structures (LIPSS) on thin films have been found to be strongly affected by the substrate where the film is deposited. We propose that this behavior is caused by surface electromagnetic field enhancement associated to the generation of surface plasmon polaritons (SPP) in the interface between thin film and substrate, that will behave as a metal because of the laser excitation. We simulated, by means of COMSOL’s Wave Optics module, the field that would result from the first pulse irradiation of a polymeric thin film on different substrates. We found that the intensity of the generated SPPs increases with the substrate roughness, however, they fail to form when the roughness increases above a certain threshold. This could mean that there is a limit to the substrate roughness that allows LIPSS generation on the surface of the thin film. Moreover, the SPP period is affected by both the material of the substrate and thin film and thickness of the thin film. We compared the period of the SPPs of our simulations with those given by the theory of SPP in thin films finding that the simulated period was always smaller than the theoretical one. We think that this is a consequence of the modification of the dispersion relation of SPPs when they travel on a rough surface, which is known to produce SPPs of increasingly smaller period the greater the roughness.
Authors : Florian Dumitrache1, Iulia I. Lungu1,2*, Claudiu T. Fleac?1, Dora D. Baciu3, Aurora Sal?geanu3, Ana-Maria Banici1, Iuliana P. Morjan1, Lavinia Gavril?-Florescu1, Simona Greculeasa4 , Gabriel Prodan5
Affiliations : 1 ? National Institute for Laser, Plasma and Radiation Physics (NILPRP), Atomistilor Str, no. 409, 077125, Bucharest-Magurele, Romania 2 ? Faculty of Applied Chemistry and Material Science, Politehnica University of Bucharest, Polizu Str., no 1-7, 011061, Bucharest, Romania 3 ? Cantacuzino National Medico-Military Insitute for Research and Development, 103 Spl. Indepenten?ei, Bucharest, Romania 4 ? National Institute of Materials Physics, Atomistilor Str., no 405 A, 077125, Bucharest-Magurele, Romania 5 ? Ovidius University of Constanta, Mamaia Avenue, no. 124, 900524, Constanta, Romania * Corresponding author: firstname.lastname@example.org
Resume : Doped or un-doped SPIONs have been used in several studies for related applications due to their magnetic properties; mainly their capacity to be controlled by an external magnetic field. The paper reports the synthesis of iodine-doped iron oxide nanoparticles using a CO2 (10.6µm) laser pyrolysis technique starting from iron pentacarbonyl and methyl iodide as iron and iodine precursors, respectively, and ethylene as laser energy transfer agent. A flow of synthetic air was also added in the reactive mixture in order to generate iron oxidation in the reaction flame. The morpho-structural properties have been determined using the following techniques: X-ray Diffractions (XRD), Energy-dispersive X-ray spectroscopy (EDS), Transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Mössbauer spectroscopy, and hysteresis loop at room temperature. The as synthesized NPs were designated for biomedical applications including contrast agents and radiotherapy; from these reasons preliminary tests regarding their cytotoxicity were performed. The present study aimed at two complementary directions: first, to evaluate the cytotoxicity of the NPs and second, to evaluate if the treatment with these agents could induce an inflammatory response in macrophages.
Authors : Ageev E.I.1, Sun Y.1, Sinev I.S.1, Mukhin I.S.1,2 , Zuev D.A.1
Affiliations : 1 ITMO University, 49 Kronverksky Ave., 197101, St. Petersburg, Russia 2 St. Petersburg Academic University, St. Khlopina, 8k3 lit. A, 194021 St. Petersburg, Russia
Resume : Modification of the near-field properties of the nanostructures is an essential task for such practical applications as the control of radiation of nanoscale light sources or sensing. The properties of oligomers can be finely controlled during the fabrication stage or by controlling the excitation light during the experiments. However, on-demand tailoring the optical response of the oligomer structure after fabrication is still a severe challenge. Here we both experimentally and numerically demonstrate the pronounced modification of the near-field pattern in hybrid gold-silicon oligomers by femtosecond laser reshaping. We study the optical properties for different degrees of fs-laser-induced modification of oligomers by visualizing it with an aperture-type near-field optical microscope and by measuring scattering spectra (for far-field properties). The near-field distributions exhibit significant changes within 720–780 nm spectral range. This effect correlates with a moderate redshift of the broadband magnetic dipole resonance of the structure that occurs upon even a slight reshaping of the gold component of the oligomers. The proposed near-field reconfiguration approach makes hybrid oligomers a promising platform for nanoscale systems with an engineered enhancement of the near-field distribution in metadevices for optical data recording sensors, and biomedical applications.
Authors : Manuel Oliva-Ramirez, Thomas Kups, Dong Wang, Peter Schaaf.
Affiliations : Chair Materials for Electrical Engineering and Electronics, Institute of Materials Science and Engineering and Institute of Micro- and Nanotechnologies MacroNano®, TU-Ilmenau, 98693-Ilmenau, Germany. https://www.tu-ilmenau.de/en/wt-wet/
Resume : Metallic nanoparticles find application in a large number of fields due to their interesting properties, which might be tailored and boosted by the alloying of several metals. The combination of five metals or more forming a solid solution is known as a High Entropy Alloy (HEA) due to their large mixing entropy. The fabrication of HEAs is still challenging in terms of bulk materials and their downsizing to the nanoscale remains quite unexplored yet. Furthermore, the fabrication of alloy nanoparticles usually involves complex wet chemical methods that seldom exceeds more than three metals. Solid State Dewetting (SSD) of metal films is a straightforward route for the fabrication of nanoparticles and is driven by minimizing the surface energy of the metal and the interphase energy between the metal and the substrate. This method has been extended so far to the fabrication of alloy nanoparticles from bi- and tri- layers of different metals by thermal annealing.1,2 In this work we present the fabrication of HEA nanoparticles by the SSD of sequentially deposited layers of Co, Cr, Cu, Fe and Ni. These metals were chosen attending to minimize the intrinsic strain of the HEAs and the stacking order regarding to minimize the surface energy and easily induce the SSD. The samples were treated by rapid annealing and a subsequent fast cooling since at high temperature the mixing entropy dominates the formation of a HEA. (1) J.Appl.Phys.2014,116(4),044307 (2) J.Mater.Chem.2012,22(12),5344
Authors : Stefan Andrei Irimiciuc(1), Sergii Chertopalov(2), Craciun Valentin(1), Michal Novotny(2), Jan Lancok(2)
Affiliations : 1National Institute for Laser, Plasma and Radiation Physics – NILPRP, 409 Atomistilor Street, Bucharest, Romania 2 Institute of Physics of the Czech Academy of Sciences, Na Slovance 2, Prague, Czech Republic
Resume : Angular and time-resolved measurements were performed by implementing the Langmuir probe technique for the investigations of transient plasmas generated by ns-laser ablation of Ag in various background gases. The aim of this work was to implement a relatively simple technique and to understand how we can control the ionic energy distribution during the deposition process. The experiments were performed on laser plasmas generated on Ag targets at a constant irradiation condition (λ = 266 nm, ν =10 Hz and E = 80 mJ) in various expansion regimes (p = 10-6 – 10 Pa). The Langmuir probe measurements were performed for two types of gasses (N2 and Ar) in order to understand the effect of background gas nature on the ionic energy distribution. The electrical investigations were mainly focused on recording the saturation ionic and electronic currents at various angles (in a 45o range) with respect to the main expansion axis at 4 cm from the target in the vicinity of the substrate holder. For each investigated pressure a time-resolved analysis was performed on the main expansion axis which allowed the determination of a wide series of plasma parameters and their spatial evolution. The novelty of the study comes from recording also the floating potential in all conditions. This approach allowed us to showcase a multiple structuring of the Ag laser produced plasmas and to reconstruct the ions energy distribution. The structuring is seen in the ionic part of the collected current and confirmed by the fast electrons distribution which matched the ionic one. Each structure characterizes an ionization state of the Ag ions, results confirmed by performing optical emission spectroscopy along the main expansion axis and discussed in the framework of multiple double layer formation during plasma expansion.
Authors : Marinescu, M. (1), Cinteza, L.O.(1), Cleciu I. (1), Matei, A. (2), Ionita, I. (3) Constantinescu, C.(4)
Affiliations : (1) University of Bucharest, Faculty of Chemistry, RO-050663 Bucharest, Romania (2) INFLPR, Lasers Department (PPAM), RO-077125 Bucharest, Romania (3) University of Bucharest, Faculty of Physics, RO-077125 Bucharest, Romania (4) Université de Limoges - CNRS, IRCER UMR 7315, 87068 Limoges, France
Resume : Pulsed laser deposition (PLD) which uses direct laser irradiation of organic molecules may induce pyrolysis and photo-chemical decomposition. A suitable choice is the MAPLE (matrix-assisted pulsed laser evaporation) technique, to develop multilayered thin films and / or embedded structures, when noncompatible solvents are available. The new 'push-pull' donor (D)-acceptor (A) chromophores developed is connected to a system of aromatic rings and azo groups which contributes to the delocalization of the pi-electrons, to obtain classic structures with optical response due to large hyperpolarizabilities that arise from a combination of strong electron-donating groups and strong electron withdrawing groups positioned at the opposite ends of a conjugated system. The azo thin film samples are investigated for their optical, morphological and chemical structure, i.e. by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), atomic force microscopy (AFM), and spectroscopic-ellipsometry (SE). To demonstrate the second harmonic generation (SHG) potential of such azo-chromophores, a pulsed femtosecond Ti:sapphire laser (80 MHz repetition rate, 800 nm, 100 fs) is employed. The pure response of azo-molecules to the electronic excitation can be resolved in contrast to the measurements on SiO2.
Authors : Simona Condurache-Bota (1), Nicolae Tigau (1), Catalin Constantinescu (2)
Affiliations : (1) Dunarea de Jos University of Galati, Faculty of Sciences and Environment, 111 Domneasca Street, 800201, Galati, Romania; (2) IRCER UMR 7315, CNRS, University of Limoges, 12 rue Atlantis, F-87068 Limoges, France
Resume : Pulsed laser deposition (PLD) of thin films has been proven for some time to be extremely versatile, despite the high price of equipment. The laser wavelength, the energy per pulse, and the spot size are some of the parameters that one can play with in order to obtain thin films with a wide range of properties and possible applications. Also, the number of pulses sent to the target in order to release the material to be deposited on a certain substrate plays a very important role for the films to be prepared, along with the nature and temperature of the substrate. This paper presents the spectacular variation with laser pulse number (N) of the optical properties of semiconducting bismuth oxide thin films prepared by PLD through the ablation of pure bismuth targets in oxygen atmosphere and onto Si/Pt substrates kept at room temperature. Thus, the reflectance of the films changes by dropping significantly when irradiating the target by 60 000 pulses vs. 40 000 pulses, while the refractive index (n), a key parameter, drops with increasing pulse number, hence with the films thickness. Still, the film roughness doesn't change significantly when the number of pulse are increasing, in spite of the general knowledge that the optical properties and roughness parameters are strongly related. Wemple-DiDomenico model was employed as one of the few models explaining of the energy bandgap of this type of films deposited onto opaque substrates, such in the case of conductive Si/Pt. The films exhibit strong anomalous dispersion, still the model can be applied on portions, showing that the bismuth oxide they are made up of a mixture of nonstoichiometric oxides and polymorphs of bismuth trioxide, especially in the case of the film prepared with 60 000 laser pulses. The mixed composition and structure which is typical for bismuth oxide films corresponds to several well-distinctive bandgaps, one for each different oxide within the films in pristine intermediate oxidation state, prior to structural and compositional stabilization. The paper has not only theoretical value, but also applicative features, since precisely the complex energy bandgap makes this kind of complex composition film proper for optoelectronic applications within several spectral domains.
Authors : Lucian PETRESCU (1,2), Maria-Catalina PETRESCU (1,2), Alexandre BOULLE (1), Catalin CONSTANTINESCU (1)
Affiliations : (1) CNRS, University of Limoges, IRCER - UMR 7315, F-87068 Limoges, France; (2) University Politehnica of Bucharest, Faculty of Electrical Engineering, RO-060042 Bucharest, Romania
Resume : We report on MnZn-type soft ferrite thin films grown on single crystal MgO substrates with various crystallographic orientations, i.e. (100), (110) and (111), by pulsed laser deposition (PLD). Their crystalline and magnetic anisotropy is investigated with respect to the chemical composition and phase. First, the morphological, structural and chemical composition of the ferrite are presented and discussed. The results reveal that high quality MnZn hetero-epitaxial thin films are grown, following the substrate's crystallographic orientation. Subsequently, the hysteresis loops are recorded and the open magnetic circuit measurements are corrected, by employing demagnetization factors by taking into consideration the local magnetic susceptibility. Finally, the hysteresis losses are estimated by the Steinmetz approach and the results are compared with available commercial information provided by selected ferrite manufacturers. Finally, the results are corroborated as the films are tailored for applications in high frequency devices, i.e. of up to several MHz, in low-to-medium power modules, and an efficiency of ~ 97-99%.
Authors : Kanidi, M.*(1,2), Papagiannopoulos, A.(1), Matei, A.(3), Dinescu, M.(3), Pispas, S.(1), Kandyla, M.(1)
Affiliations : (1) Theoretical and Physical Chemistry Institute, National Hellenic Research Foundation, 48 Vasileos Constantinou Avenue, 11635 Athens, Greece (2) Department of Material Science, University of Patras, University Campus, 26504 Rio, Greece (3) National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor, 077125 Magurele-Bucharest, Romania
Resume : We develop functional surfaces of laser-microstructured Si, spin-coated with thermoresponsive PS/PNIPAM polymer blends and we study their switchable wetting behavior between hydrophilicity and hydrophobicity upon heating. PNIPAM is a thermoresponsive polymer, which is hydrophilic below 32oC and hydrophobic above 32oC. We take advantage of the large specific area and roughness of the micro-Si substrate to enhance the PS/PNIPAM film thermoresponsiveness. Microstructured Si substrates were fabricated by ns laser irradiation in SF6 gas. PS/PNIPAM blends, of various blend ratios, in THF were spin-casted onto flat and micro-Si substrates, with or without a native SiO2 layer. The wetting state of PS/PNIPAM films was determined by water contact angle measurements. The morphology of the surfaces was mapped by SEM and the chemical composition by EDS and micro-Raman spectroscopy. The depth-resolved chemical composition of the polymer films was provided by XPS. Upon heating, films on micro-Si switch from hydrophilic to hydrophobic. The transition is reversible for multiple heating/cooling cycles. Films casted on flat silicon do not undergo switching of their wetting behavior, even though they respond moderately to temperature. When films are casted on silicon with native SiO2, they show higher thermoresponsiveness, compared to substrates without SiO2. XPS reveals this is due to the arrangement of PS and PNIPAM in the films, depending on the presence or absence of the underlying SiO2.
Authors : P. Sopeña(1,2), E. Martí-Jerez(1,2), M. Duocastella(1,2), P. Serra(1,2), J.M. Fernández-Pradas(1,2)
Affiliations : (1) Department of Applied Physics, Universitat de Barcelona, Martí i Franquès 1, 08028, Barcelona, Spain (2) Institute of Nanoscience and Nanotechnology (IN2UB), Universitat de Barcelona, Av. Diagonal 645, 08028, Barcelona, Spain
Resume : Laser-induced forward transfer (LIFT) is a direct-write method used to print materials from liquid suspensions. Almost all kinds of inks, independently of their viscosity value and loading particle size, can be printed by means of LIFT since it is nozzle-free. This is beneficial for printed electronics applications since high solid content inks, like those employed in screen printing (SP), can be transferred digitally. These inks exhibit a high-viscosity due to the strong interaction in the highly packed arrangement of particles related to the elevated loading contents, which normally results in shear-thinning behaviors. Thus, these properties make SP inks unprintable using other already established direct-write technologies such as inkjet printing. In this work we studied the printing of continuous stable interconnects of commercially-available SP inks by means of LIFT. First, we printed single voxels by varying the main transfer parameters such as the laser pulse energy or the donor-receiver distance, which reveals a rather linear relationship between the voxel volume and the pulse energy for low energies and small gaps. Then, we changed the overlap between adjacent voxels in order to obtain uniform continuous lines and areas. A time-resolved visualization experiment of the transfer mechanism helps to correlate the printing results with the observed trends.
Authors : Claudiu T. Fleaca1, Evghenii Goncearenco1, Florian Dumitrache1, Ana-Maria Banici1, Marius Dumitru1, Catalin Ducu2 Valentin S. Teodorescu3
Affiliations : 1 - National Institute for Laser, Plasma and Radiation Physics (NILPRP), 409 Atomistilor Str., 077125, Bucharest-Magurele, Romania 2 - National Institute for Materials Physics (NIMP), 405A Atomistilor Str., 077125, Bucharest-Magurele, Romania 3 - University of Pitesti, Targul din Vale street no.1, 110040, Pitesti, Arges county, Romania
Resume : We report the synthesis and characterization of a series of alkali-doped (Li, Na, K and Cs) iron oxide nanoparticles using nanomaghemite obtained by laser pyrolysis (from Fe(CO)5 vapors) which were impregnated with Li citrate or Na, K, Cs nitrates salts followed by 500°C thermal annealing. The powders were characterized by XRD, EDS, SEM, TEM, FTIR and/or XPS techniques, revealing the presence of hematite/maghemite phases. They were deposed from aqueous suspensions as washcoat layers inside coridierite monoliths channels and the resulted dry supported catalyst were tested with promising results for the selective catalytic reduction (SCR) of NOx with ammonia using Diesel engine exhaust simulated mixture.
Authors : A. Nikolov (1), N. Stankova (1), E. Pavlov (1), N. Nedyalkov (1) and D. Karashanova (2)
Affiliations : (1) Institute of Electronics, Bulgarian Academy of Sciences, 72, Tsarigradsko Chaussee, Sofia 1784, Bulgaria (2) Institute of Optical Materials and Technologies, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Building 109, 1113 Sofia, Bulgaria
Resume : The fundamental wavelength and the second, third and fourth harmonics of a Nd:YAG nanosecond pulsed laser system are used to produce nanoparticles by pulsed laser ablation of a noble metal target immersed in double distilled water. An external dc electric field directed at different angles to the direction of the laser beam propagation is applied to study its impact on the morphology of the created nanoparticles by varying the electric field strength and the laser fluence. The profile of the optical transmission spectrum is used to indirectly assess the morphology of the ablated material. The nanostructures obtained are visualized by transmission electron microscopy (TEM), and their microstructure is studied by high-resolution transmission electron microscopy (HRTEM) and selected-area electron diffraction (SAED). Noble metal nanoparticles are expected to find many applications; among those, the biomedical uses and surface enhanced Raman spectroscopy are of particular importance, where controlling the nanoparticles’ shape is a major way of optimizing their effect.
Authors : Dagault L. (1,2), Kerdilès S. * (1), Acosta Alba P. (1), Hartmann J.-M. (1), Cristiano F. (2)
Affiliations : (1) Université Grenoble Alpes and-CEA-LETI, 17 rue des Martyrs, 38054 Grenoble, Cedex 9, France. (2) LAAS, CNRS Université de Toulouse, 7 av. Colonel Roche, 31400 Toulouse, France. * lead presenter
Resume : Nanosecond laser annealing (NLA) is expected to be the next generation of thermal treatments in microelectronics. NLA, especially in the melt regime, enables dopant activation at record high concentrations. The melted depth is controlled by the laser energy density (ED). NLA can be performed in a step and repeat mode or by scanning the surface. At the edges of the beam, laser intensity intercepts melting threshold conditions at which surface roughness reaches a maximum. To understand and minimize it, we investigated the behavior of Si and SiGe surfaces upon NLA around the onset of melt. Si1-xGex epilayers (0 ≤ x ≤ 0.4) were submitted to NLA in a SCREEN LT3100 platform with a XeCl laser (308 nm wavelength, ~100-200 ns pulses). Laser ED range was chosen in order to investigate the various annealing regimes from sub-melt to full SiGe layer melt, with a focus on the melt threshold region. Samples were characterized by SEM, TEM, AFM and Energy Dispersive X-Ray analysis. For the first time, we evidenced that, when increasing laser ED around the melt threshold, there was, on Si and SiGe surfaces, more and more molten islands that merged into a continuous molten layer, in the end. Such isolated nanostructures were typically 50-400 nm wide and their morphology depended on the crystal orientation and the surface preparation prior to NLA. Leveraging Ge segregation towards the surface during the melt of SiGe, we also extracted their total height and depth beneath the surface.
Authors : A. Nikolov (1), N. Stankova (1), A. Dikovska, N. Nedyalkov (1) and D. Karashanova (2)
Affiliations : (1) Institute of Electronics, Bulgarian Academy of Sciences, Tsarigradsko Chaussee 72, Sofia 1784, Bulgaria (2) Institute of Optical Materials and Technologies, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Building 109, 1113 Sofia, Bulgaria
Resume : Nanosecond pulsed laser ablation in liquids is utilized to create novel nanocomposite materials based on titanium with added Ag, Au, Pt or Pd. These materials implemented in different modifications as alloys, core-shell or dumb-bell like structures are intended to find application in, e.g., photo-catalysis, biomedicine, etc. The fundamental wavelength and the second, third and fourth harmonics of a Nd:YAG laser system are used as an ablation source. The target materials are different and correspond to the specified nanocomposite. The appropriate laser wavelength is chosen depending on the morphology of the nanocomposite we seek to obtain. Changing the composition of the nanocomposite and its morphology is achieved by controlling the energy density of the laser radiation at a given wavelength. The product of the ablation process is an aqueous colloid of the respective nanocomposite. Indirectly, the changes in the nanocomposites’ composition and morphology are monitored by the changes in the profile of the colloids’optical transmission spectra. Transmission electron spectroscopy (TEM) is used to visualize the shape, size and size-distribution of the nanocomposite particles. Their phase composition is evaluated using high-resolution transmission electron microscopy (HRTEM) and selected-area electron diffraction (SAED).
Authors : A.F. Bonciu, E. Sirjita, A. Palla-Papavlu, M. Dinescu
Affiliations : A.F. Bonciu 1) National Institute for Lasers, Plasma and Radiation Physics, Magurele, Bucharest, 077125, Romania 2) University of Bucharest, Faculty of Physics, RO 077125, Magurele, Romania E. Sirjita 1) National Institute for Lasers, Plasma and Radiation Physics, Magurele, Bucharest, 077125, Romania 2) University of Bucharest, Faculty of Physics, RO 077125, Magurele, Romania A. Palla-Papavlu 1) National Institute for Lasers, Plasma and Radiation Physics, Magurele, Bucharest, 077125, Romania M. Dinescu 1) National Institute for Lasers, Plasma and Radiation Physics, Magurele, Bucharest, 077125, Romania
Resume : Attacks on national security of different European states as well as on the lives of their citizens have become a daily reality. Explosives and precursor materials are used in most of these attacks, which lead to the need for new detection solutions and technologies. Explosives are chemically unstable materials difficult to detect due to the low vapor pressure, therefore, novel devices and detection systems based on fully integrated arrays are of interest. In this work, we are focusing on fabricating sensor arrays based on chemiresistive sensors with proven sensing functionality for volatile organic compounds such as ammonia, acetone, and ethanol. The active materials in the sensor arrays are based on carbon nanotubes (CNT) and functionalized carbon nanotubes. For the fabrication of the sensor arrays, laser induced forward transfer (LIFT) is applied to transfer CNT pixels onto metallic electrodes. The distribution of the CNTs onto the metallic electrodes is investigated by scanning electron microscopy. Raman spectroscopy is used to check for any chemical modification in the transferred materials. Finally, the sensing characteristics, i.e. sensitivity, response and recovery times, selectivity are evaluated for the CNT and functionalized CNT based sensor arrays. Following these results one can envision that active sensing materials based on CNTs can be applied in explosive sensor arrays using laser technique. Acknowledgement Financial support from UEFISCDI, though the “Fabrication, calibration, and testing of advanced integrated sensor systems aiming at applications in societal security (TESTES)” project is gratefully acknowledged.
Authors : R. Birjega, A. Matei, A. Vlad, A. I. Trefilov, M. Dinescu, M.C. Corobea, R. Zavoianu, O.D. Pavel, M. Osiac
Affiliations : R. Birjega, A. Matei, A. Vlad, A. I. Trefilov, M. Dinescu to National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Str., 077125 Bucharest, Magurele, Romania; M.C. Corobea to Romanian National R.&D. Institute for Chemistry and Petrochemistry, ICECHIM, 202 Splaiul Independentei Str., CP-35-274, 060021 Bucharest, Romania ; R. Zavoianu, O.D. Pavel University of Bucharest, Faculty of Chemistry, Department of Chemical Technology and Catalysis, 4-12 Regina Elisabeta Bd., Bucharest, Romania; M. Osiac to University of Craiova ,Faculty of Physics,13 Al. I. Cuza Str., 200585 Craiova, Romania
Resume : Polymer nanocomposites attracted a great interest not only for academic studies but also in industry side because of their cost/properties, energy/properties and weight/properties profiles useful for improved or novel mechanical, optical and physic-chemical properties, thermal stability, reduced gas permeability and in particular, in the area of flame retardancy. A serious drawback of using neat polymers in several applications is their high heat and smoke generation and possible toxic gases release. To improve the thermal and the thermo-dynamic mechanical properties during plasma transport, the adhesion of the coatings, the chemical groups availability on the coatings surface (i.e. polar or non-polar character) and the suppression of potential gas release, suitable additives were added. Used as thin coatings such polymer nanocomposites will convey improved protective properties to the materials they covered. We used pulsed laser deposition (PLD) to obtained polymer nanocomposites coatings. Two types of condensation polymer matrix were used, one based on ethylene-co-vinyl acetate copolymer (EVA) and a polyamide homopolymer (PA) As inorganic additives an Mg-Al layered double hydroxide (LDH), two organo-modified Mg-Al LDHs, a Mo-modified Mg-Al LDH and graphene oxide (GO) were used. The polymer nanocomposites obtained either by compression moulding or by injection moulding were used as targets for PLD deposition. The coatings were deposited on different substrates at room temperature using an Nd:YAG laser operating at 532 nm and 1064 nm wavelengths. The morphological, chemical –structural characteristics and functional properties of the nanocomposites based on EVA and PA polymers, targets and derived coatings, were screened using the usual techniques (XRD, SEM, AFM, and FT-IR, DRIFTS, UV-Vis, and Raman spectroscopy).
Authors : Gianina F. Popescu-Pelin1, Dorel F. Albu2, Jeanina Lungu2, Adrian Georgescu2, Ion. N. Mihăilescu1, Mihai A. Gîrțu2 and Gabriel Socol1
Affiliations : 1National Institute for Lasers, Plasma and Radiation Physics, Magurele 077125, Ilfov, Romania 2Department of Physics, Ovidius University of Constanța, Constanta 900527, Romania
Resume : We report on the pulsed laser deposition (PLD) synthesis of four batches of TiO2 coatings in different gaseous atmospheres (O2, N2, Ar și He) as photoanodes in the structure of dye-sensitized solar cells (DSSC). Two TiO2 layers were deposited for each batch (a thin nanostructed one and a high density one) by using a KrF* excimer laser (λ= 248 nm și τFWHM = 10 ns) and applying a 10 and 40 Hz laser repetition rate. The morphology, topography and crystalline structure of the coating were evaluated by scanning electron microscopy (SEM), atomic force microscopy (AFM) and X-Ray Diffraction (XRD), respectively. Depending on the ambient gas pressure during the PLD depositions, the SEM micrographs revealed morphological differences between samples. Furthermore, the AFM results are in good agreement with the SEM ones. The crystallographic assessment of the TiO2 samples highlighted the presence of a mixture of anatase and rutile with low crystallinity. The photovoltaic performance studies were carried out to understand and evaluate the effect of the TiO2 bilayer (the interaction with the dye molecules) on the cells efficiency.
Authors : L. N. Dumitrescu1, A. Matei1, R. Birjega1, A. Vlad1, A. I. Trefilov1, M. Dinescu1, M. Secu3, A. Marinescu1, V. Raditoiu4, M.C. Corobea4, R. Zavoianu2
Affiliations : 1National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Str., 077125 Bucharest, Magurele, Romania 2University of Bucharest, Faculty of Chemistry, Department of Chemical Technology and Catalysis, 4-12 Regina Elisabeta Bd., Bucharest, Romania 3National Institute for Materials Physics, P.O. Box MG-7, 77125 Bucharest-Magurele, Romania 4Romania National R.&D. Institute for Chemistry and Petrochemistry, ICECHIM, 202 Splaiul Independentei Str., CP-35-274, 060021 Bucharest, Romania
Resume : Nowadays, photochromic systems are the subject of more industry-funded research in the field of high-tech applications that have the potential to become the most important commercialization point for photochromic dye. Our interest is in smart systems, sensors, printed or stamped elements due to their potential applications in these sectors. Here, we report on the fabrication of a photoluminescent coatings using Matrix Assisted Pulsed Laser Evaporation (MAPLE) technique. An organic dye with a spiropyran structure was prepared to be used as target in three different forms: i) as prepared, ii) microencapsulated in a poli oximetilen melamine resin matrix, iii) embedded in a layered double hydroxide matrix. Photochromic dyes like spiropyran materials synthesized via laser processing have not yet been reported. The spiropyran dye and spiropyran-based materials were transferred by UV laser (266 nm) on different types of substrates. In the present work, we studied the optical, morphological and the photochromic properties of the organic dyes thin films obtained by MAPLE, emphasizing the protective matrix function. Different techniques, as AFM, XRD, FT-IR, DRIFTS, DR-UV-Vis and Raman spectroscopic measurements have been used for the morphologic and structural characterization of the organic dyes films. A photochromic study was performed by measuring the photoluminescence (PL) emission spectra and fluorescence microscopy images of the as deposited spiropyran dye-based films.
Authors : A. Palla Papavlu1, M. Filipescu1*, A. Radu1,2, N. Enea1, O. Uteza3, M. Dinescu1
Affiliations : 1 National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Steet, Magurele, Romania 2 University of Bucharest, Faculty of Physics, 405 Atomistilor, P.O. BOX MG-11, 077125, Magurele, Romania 3 LP3 - Lasers, Plasmas et Procédés Photoniques Aix-Marseille Université, CNRS, UMR 7341, France
Resume : In order to operate with high-power lasers, it is necessary to have high performing and resistant optics. The aim of this work is to test the resistance of antireflection coatings that can be used for ultra-short high-power lasers beam delivery/handling systems. At the present time, one of the biggest problems when operating high power lasers is the systematic damage coatings applied to various optical components. The use of antireflection (AR) coatings reduces the unwanted reflections from surfaces, keeping only the desired component, for which the reflectivity can reach up to 99.99%. In order to have high reflections for a range of wavelengths and diminished (antireflection) for another range, some more elaborate mirrors were developed. Generally, the optical coating is a dielectric material (e.g. metal oxide) deposited as thin film on optical support (quartz). The antireflection coatings are based on multi-layers with different refractive indices by pulsed laser deposition (PLD). The materials that were used are cheap and have repeatedly demonstrated their efficiency for this purpose: Hf, Al and Si oxides. In the frame of this work, heterostructures formed from 5 to 7 different layers should be tested to ultra-short high-power laser beam in order to determine the LIDT values and to advance their applicability in ultra-high peak power facilities.
Authors : Elena Dutu 1, Monica Scarisoreanu 1, Evghenii Goncearenco 1, Claudiu Fleaca 1, Iuliana P. Morjan 1, Lavinia Gavrila-Florescu 1, Ion Sandu 1, Valentin Teodorescu 2, Ioan Balint 3
Affiliations : 1 National Institute for Lasers, Plasma and Radiation Physics, Atomistilor str., 409, Magurele, Ilfov, 077125, Romania 2 National Institute of Materials Physics, Atomistilor str., 405 A, Magurele, Ilfov, 077125, Romania; 3 Romanian Acad, Inst Phys Chem Ilie Murgulescu, 202 Spl Independentei, Bucharest 060021, Romania
Resume : This work presents the preparation of tin oxide and titanium dioxide nanoparticles using laser pyrolysis (LP) technique followed by the decoration of these nanoparticles with noble metals using chemical impregnation method. Sensitized mixtures of TiCl4 and SnCl4 precursors were used in the presence of oxygen in order to obtain nanoparticles of semiconductor oxides through laser pyrolysis method. The noble metal decoration was started using chemical impregnation of the collected materials with the aqueous solution of noble metal precursors (AgNO3, KAuCl4), to improve the functional properties of oxide semiconductors. Structural, morphological and optical properties of the obtained decorated nanopowders have been characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman spectroscopy, energy-dispersive X-ray spectroscopy (EDX) and UV–vis diffuse reflectance spectroscopy (DRS) techniques. The sensory and photodegradation properties of nano-oxides decorated with noble metal were tested, showing that for the photodegradation of perchlorethylene (PCE) carried out under UV-VIS light irradiation, the presence of noble metals on the TiO2 surface drastically improves the photocatalytic activity, especially if Au is used. Adding noble metals on the surface of the e oxide semiconductors nanoparticles has been proven to be an effective strategy to enhance functional properties of these materials.
Authors : N. Enea1 , V. Ion1, F. Craciun2, R. Birjega1, M. Dinescu1, N.D. Scarisoreanu1, C. Viespe1
Affiliations : 1 National Institute for Laser, Plasma and Radiation Physics, 409 Atomistilor St, Magurele, Romania 2 CNR-ISC, Istituto Dei Sistemi Complessi, Via del Fosso del Cavaliere 100, I-00133 Rome, Italy
Resume : Searching new types of environmental friendly piezoelectric materials is an important tendency nowadays for replacing materials currently used that contain toxic elements such as lead. One of the key materials that has proven by latest research to be a good candidate for replacing lead-based materials is (Ba1?xCax)(ZryTi1?y)O3 (BCZT) due to the strong piezoelectric response and its high dielectric constant. From the point of view of the piezoelectric activity presented in volumetric form, the BCZT solid solution with perovskite structure exhibits similar or even higher piezoelectric coefficients values as compared with the most used lead based compound-PbZrTiO3. The use of ecological piezoelectric thin films in acoustic sensors is very important especially in disposable electronics or food industry. We report obtaining SAW sensors based on strain engineered BCZT epitaxial films. The BCZT thin films with various stoichiometries (x= 45, 50, 55) were deposited using Pulsed Laser Deposition technique on STO or GSO substrates aiming at varying both induced strain level into the films and the compositions. The films thus deposited were studied by different techniques. The SAW tests were performed by applying an electrical signal to one of the transducers to generate a surface acoustic wave, which was subsequently transformed into an electrical signal. The functional characteristics of the SAW devices are discussed as a function of film?s compositions and induced structural strain.
Authors : D. Manica 1, 3 , G. Socol1, G. Popescu-Pelin1 , V. Ion1, M. Dinescu1 , N.D. Scarisoreanu1, V. Teodorescu2
Affiliations : 1NILPRP, P.O. Box MG-16, RO-77125, Magurele, Romania. 2NIMP-National Institute of Materials Physics, 077125, Magurele, Romania 3 Faculty of Physics, University of Bucharest, 077125, Magurele, Romania
Resume : Bismuth ferrite (BiFeO3) is the only known material exhibiting good simultaneous ferroelectric and antiferromagnetic orderings at room temperature, having a distorted rhombohedral perovskite crystal structure. This material is the basis for a wide range of applications in different fields, one of the promising applications for BFO materials being the photodegradation of organic pollutants. A variety of techniques are known for obtaining nanostructures, with different advantages and disadvantages. A simple and versatile technique is laser ablation in liquid. Using pulsed laser ablation in liquid-PLAL technique, we have synthesized different type of nanostructures of BiFeO3 based materials by varying the working parameters. Laser wavelength demonstrated to be very important as single-crystalline sheets nanoparticles with a narrow mean-size distribution or a combination of the two have been obtained for different wavelengths. The average nanostructures size and morphology was estimated by TEM and the optical properties by UV-Vis spectrometry. In this study we present the results of using pure BFO and rare-earth elements doped BFO nanostructures obtained by PLAL for rhodamine B degradation. Comparisons have been made between suspensions with different concentrations of nanostructures, as well as different rare earth dopants (Y, La). It was observed that the nanostructures obtained by laser ablation in the liquid have a high photocatalytic efficiency, and a good response over time
Authors : Valentin ION1, Nicu D. SCARISONEANU1, Nicoleta ENEA1,2, Ruxandra BIRJEGA1, and Maria DINESCU1
Affiliations : 1) National Institute for Laser, Plasma and Radiation Physics, Magurele, Romania 2) University of Bucharest, Faculty of Physics, Magurele, Romania
Resume : The multiferroic perovskite materials with low band-gap are very attractive for photovoltaic and photocatalytic applications. One of the most investigated multiferroic ABO3 compound is bismuth ferrite (BiFeO3) with a value of bandgap 2.7-2.8 eV. Through doping with rare earth elements (Yttrium, Lanthanum, etc) in different concentration the bismuth ferrite bad gap can be lowered from 2.7 eV to 1.9-2 eV. K:BFO is a recently identified multiferroic, derived from perovskite BFO with a A2B2O5 crystalline structure (brownmillerite). In the KBFO structure, the Fe2O3 block alternates with KBiO2 block (BO6 octahedra with BO4 tetrahedra). In this work, we report the optical properties of thin films of KBFO deposited by pulsed laser deposition method (PLD) on different substrates: Pt/Si, SrTiO3, Nb doped SrTiO3, SrRuO3/SrTiO3 and GdScO3. A parametric study on the influence of deposition parameters on the optical properties of the thin layer was carried out. Crystallinity properties and topography of surface of thin films were studied using X-ray diffraction, scanning electron microscopy (SEM) and atomic force microscopy (AFM). The optical properties were determined by spectroscopic ellipsometry (SE) in the 250-1700 nm range of wavelength and the values of band gap (Eg) where determined from Tauc plot. The obtained value of band gap is in the range of 1.59 to 2.1 eV and depends on substrate nature.
Authors : F. Andrei1,2, N.D.Scarisoreanu1, N. Enea1, V. Ion1, A. Moldovan1, I. Boerasu1, R. Birjega1, M. Dinescu1
Affiliations : 1. National Institute for Laser, Plasma and Radiation Physics; 2. Faculty of Chemistry, University of Bucharest.
Resume : Perovskite nanomaterials are of great interest in the 21st century. They are widely explored for optoelectronic devices, photovoltaic and light emission applications. Furthermore, they can be used as thermoelectric and magnetic materials and they are useful in multicolour biological imaging. Ferrite materials show numerous captivating properties correlated with strong absorption of visible light which recommend them as excellent candidates for reactions such as: water photodecomposition and photodegradation of organic pollutants. Lanthanum orthoferrite (LaFeO3) has perovskite structure and it can exhibit ferroelectric and ferromagnetic properties similar to BiFeO3. It can be used for numerous applications such as electrodes for fuel cells, chemical sensors, optoelectronic devices, catalysts and photocatalysts. Bulk LaFeO3 is considered to be an antiferromagnetic material with a very high Neel temperature. In photoelectrochemical applications, it is very important for the material to absorb light in the visible region. LaFeO3 is a material having an optical band gap ~ 2.07 eV with the absorption capacity mainly in the visible region of the spectrum and it receives considerable attention due to of its strong photocatalytic activity. In this study, LaFeO3 thin films were deposited via pulsed laser depositon (PLD) technique. Their optical properties were analysed according to: the used oxygen pressure during the deposition process; the used substrate for deposition; the number of laser pulses.
Authors : H.H. Gullu1, C. Emir1, M. Parlak2,3
Affiliations : 1Department of Electrical and Electronics Engineering, Atılım University, Ankara 06830, Turkey; 2Department of Physics, Middle East Technical University, Ankara 06800, Turkey; 3Center for Solar Energy Research and Applications (GÜNAM), Middle East Technical University, Ankara 06800, Turkey
Resume : II-VI semiconducting thin films have become a great part of research interest due to their possibility to use in a wide range of device applications with their remarkable optoelectronic properties as ideal direct band gap, high absorption coefficient and photosensitive behavior in the visible region of spectrum. Based on these optical and electrical properties, these compounds have been investigated as an alternative material system in the fabrication of low cost optoelectronic devices and used as promising materials for the development of current technological devices. Among these compounds, zinc selenide (ZnSe) thin film has long been popular in the field of optoelectronics due to their high transparency in visible region, direct and wide band gap value, photoconductivity, high electron affinity and n-type semiconducting behavior. Although this type of films has potential applications in fabrication of light emitting diodes, thin film transistors, gas sensors, photodetectors and solar cells, in recent years, attention has been directed to alternative methods as variations in chemical constituents, doping, formation of ternary analogues, surface patterning in order to manipulate the material characteristics of thin films to improve the performance of the devices. In this study, ZnSe thin ﬁlms were deposited on a soda-lime bare glass substrates using direct electron-beam evaporation of high purity and stoichiometric ZnSe powder at room temperature. Bare glass substrates were used in thin film characterization processes and also employed to tailor its optical properties for possible device applications. For the deposited ZnSe thin films, energy dispersive X-ray (EDS) analysis showed an average atomic percentage of ZnSe is near to stoichiometric composition of the source material as Zn:Se ratio (50:50). The X-ray diffraction profile of the samples was indexed according to JCPDS files and the characteristics diffraction peaks were observed in a good agreement with the literature without any formation of secondary phase in the structure. The surface imaging using scanning electron microscopy (SEM) and detailed surface morphology analysis by using atomic force microscope (AFM) showed that the deposited ZnSe thin ﬁlms are dense and compact in nature. From the optical transmission studies, films were found in direct optical transition characteristics and the band gap values of the samples were calculated using Tauc plots. In addition, substrate-assisted laser patterning was investigated as an alternative technique to create functional structures for possible optoelectronic applications. The straight and continuous line patterns on bare glass substrates were optimized in terms of pulse repetition rate, laser power, pulse energy and the feeding speed of the nanosecond pulsed Nd:YAG laser system. Uniform periodic pattern without any damage to the glass substrates were achieved with a wavelength in the infrared region. It was observed from EDS spectrum of the films that the stoichiometric transfer of material from source powder to the deposited films on different substrates with different line patterns was achieved. In the case of surface morphology, the effects of laser patterning on characteristics of the ZnSe thin films deposited on glass substrates were investigated by SEM and AFM images. UV/Vis spectrophotometer was used to discuss the transmittance and reflectance characteristics of these patterned samples.
Authors : Mihaela Filipescu1, Florin Andrei1, Anca F. Bonciu1,2, Alexandra Palla-Papavlu1, Maria Dinescu1
Affiliations : 1- National Institute for Lasers, Plasma and Radiation Physics, Magurele, Bucharest, 077125, Romania 2- University of Bucharest, Faculty of Physics, RO 077125, Magurele, Romania
Resume : Biosensors are the principal devices in products designed for healthcare monitoring systems as they are attractive competitors of the bulky, expensive, and complex analytical instruments currently used in medical applications. However, recent estimates show that the biosensor and electrochemical sensor market are dominated by glucose sensors. Therefore, there is a great need to expand the application of biosensors beyond glucose. Even more, taking into account the rapid development of the society’s needs, concepts such as intelligent clothing and wearable devices receive increasing attention. In addition, new features such as portable, flexible, and real-time monitoring become more and more important. In the last years, recent approaches are focused on wearable electrochemical sensors, which can detect target analytes (i.e. a variety of heavy metals) in saliva, tears, sweat, and interstitial fluid. The aim of this work is the development of an original flexible and wearable biosensor based on polymers and graphene fabricated by laser-induced forward transfer. In particular, we focus on the transfer of donor materials and the optimization of the LIFT process for obtaining reproducible pixels which are used as electrodes for the electrochemical biosensors. We printed different polymer:graphene nanocomposites onto flexible substrates (coated with an insulating layer, for ex. Parylene C, which prevents electrical contact with the body fluids). The biosensors fabricated by LIFT are used for the detection of heavy metals in human body fluids. Acknowledgement Financial support from i) NILPRP through the NUCLEU program and ii) UEFISCDI, though the “Smart flexible biosensor via laser transfer for body fluids monitoring (iFLEX)” project are gratefully acknowledged.
Authors : Eduard Sirjita1,2, Mihaela Filipescu1, Alexandra Palla-Papavlu1, Maria Dinescu1
Affiliations : 1- National Institute for Lasers, Plasma, and Radiation Physics, Magurele, ZIP 077125, Romania 2- University of Bucharest, Faculty of Physics, Magurele, ZIP 077125, Romania
Resume : This paper describes a rapid, solvent-free (laser based) procedure for the fabrication of sensitive sensors based on hybrid nanocomposites, i.e. single walled carbon nanotubes decorated with oxide nanoparticles that overcomes challenges associated with solvent-assisted chemical functionalization and integration of these materials into devices. In this work, we are focusing on fabricating sensor arrays based on chemiresistive sensors with proven sensing functionality for volatile organic compounds such as ammonia, acetone, and ethanol. The active materials in the sensor arrays are based on carbon nanotubes (CNT) and CNT decorated and/ or functionalized with oxide nanoparticles (for ex. SnO2). The oxide decorated CNTs are obtained by spin coating the oxide nanoparticle suspension onto the already grown CNT films. For the fabrication of the sensor arrays, laser induced forward transfer (LIFT) is applied to transfer CNTand oxide-CNT pixels onto metallic electrodes. The distribution of the transferred materials onto the metallic electrodes is investigated by scanning electron microscopy. Raman spectroscopy is used to check for any chemical modification in the transferred materials. Finally, the sensing characteristics, i.e. sensitivity, response and recovery times, selectivity are evaluated for both the CNT and oxide-CNT based sensor arrays. It has been found that the oxide-CNT arrays show a better sensitivity and a decreased recovery time (of approx. 20 seconds) than the CNT based sensor arrays. Following these results one can envision that active sensing materials based on CNTs and oxide-CNT can be applied in explosive sensor arrays using laser techniques. Acknowledgement Financial support from UEFISCDI, though the “Fabrication, calibration, and testing of advanced integrated sensor systems aiming at applications in societal security (TESTES)” project is gratefully acknowledged.
Authors : W. Karim , M. Mickan , A. Petit , M. Tabbal , A.L. Thomann and N. Semmar
Affiliations : GREMI-UMR 7344-CNRS-University of Orleans, 14 rue d’Issoudun, BP6744, 45071 Orleans Cedex2, France
Resume : The interaction between ultrashort laser beam pulses (40 ps) with gadolinium-doped ceria (CGO) thin films induces the formation of surface micro/nanostructures. These laser-induced periodic surface structures (LIPSS), or ripples, play a very important role to improve the physico-chemical properties of thin films as specific surface. In the case of electrochemical cells made of thin film assembly, they can further enhance the performance of the electrode by increasing the reactions of the active species at the electrode/electrolyte interface. A Nd: YAG laser beam at the third harmonic (355 nm) is employed to irradiate a 4 X 4 mm2 upon the surface of CGO thin layer, that was deposited by magnetron sputtering. The morphological and clear features of the ripples were observed on CGO thin films by high resolution scanning electron microscopy (HR-SEM). LIPSS are generally produced in a low fluence laser multi-pulse regime close to the ablation threshold. They were obtained with the period of approximately 220 nm under appropriate values of laser fluence (F from 138 to 417 mJ/cm2) and scanning speed (1 mm/s to 5 mm/s). In agreement with literature, it has been noted that these periodic structures can be distinguished as function of their period, that we can classify as low spatial frequency LIPSS (LSFL) and high spatial frequency LIPSS (HSFL). In this work, we focus on the optimization of laser parameters to generate clear and high resolution LSFL/HSFL. Using numerical tools for SEM/AFM images, the enhancement of the specific surface will also be discussed.
Authors : Oana Gherasim1,2, Alexandru Mihai Grumezescu2,*, Valentina Grumezescu1, Alina Maria Holban3, Ecaterina Andronescu2
Affiliations : 1National Institute for Lasers, Plasma & Radiation Physics, Lasers Department, P.O.Box MG-36, Bucharest-Magurele, Romania; 2University Politehnica of Bucharest, Faculty of Applied Chemistry and Materials Science, Department of Science and Engineering of Oxide Materials and Nanomaterials, Polizu Street no 1-7, 011061 Bucharest, Romania; 3Faculty of Biology, University of Bucharest, Microbiology Immunology Department, Aleea Portocalilor 1-3, Sector 5, 77206-Bucharest, Romania
Resume : The ability of microbial strains to grow in biofilms represents one of the main factors of persistent infections in hospitalized patients. Such multicellular attached communities could develop on medical devices and surfaces, causing implant failure and prolonged hospitalization. The aim of this study was to obtain laser modified bioactive surfaces containing graphene oxide and silver nanoparticles (NPs) with antimicrobial effect. The surfaces were obtained by MAPLE (matrix assisted pulsed laser evaporation) and physico-chemically characterized by DRX, DTA-TG, SEM and MIR. Antimicrobial effect was assessed against relevant Gram positive (Staphylococcus aureus and Enterococcus faecalis) and Gram negative (Pseudomonas aeruginosa and Escherichia coli) species. The results revealed that the obtained NPs present crystalline structure, nanometric size and low aggregation, while the laser processed coating is thin and uniformed when a fluence of 400 mJ/cm2 is applied. The nanomodified thin films demonstrated and increased potential to inhibit microbial colonization and biofilm development, being more active against Gram negative monospecific biofilm development. Our study reveals that the developed coatings could be applied for the development of new bioactive surfaces and devices with anti-biofilm effect.
Authors : I.A. Paun (1,2), B.S. Calin (1,2), C.R. Luculescu (1), M Dinescu (1)
Affiliations : (1) INFLPR - National Institute for Laser, Plasma and Radiation Physics, Center for Advanced Laser Technologies (CETAL), Magurele-Ilfov, RO-077125, Romania; (2) UPB - University Politehnica of Bucharest, Faculty of Applied Sciences, RO-060042, Romania
Resume : 3D structures were produced by LDW via TPP in biocompatible photopolymers using fs laser at powers from 10 to 40 mW and scanning speeds from 10 to 100 µm/s. A parametric study was carried out for identification of the best combination of the two parameters for obtaining an accurate geometry control of the written structures as well as a high spatial resolution. The design of the 3D structures was calculated using Python 3.6.6. All information related to structure geometry is delivered as a list of carthesian points, appropriately configured for the 3D lithography installation (Nanoscribe Photonic Professional). The Python script also delivers a separate file that is used for setting laser writing parameters and also centralizing all geometry files.The study was focused on vertical microtubes with high aspect ratio that were used to improve the quality of the 3D structuring. Several phtopolymers suitable for biomedical applications were tested, such as IP-L780 and Ormocore. For each photopolymer, laser scanning speed/laser power maps were produced. The obtained structures were investigated in terms of morphology and aspect ratio. The optimum laser processing parameters were selected.
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|08:45||PLENARY SESSION 3|
Photonic curing: methods & emerging applications : Yaroslav ROMANYUK
Authors : Nikhil Pillai, Rudy Ghosh*, Vahid Akhavan, Ian Rawson, Vikram Turkani, Harry Chou, Stan Farnsworth
Affiliations : NovaCentrix, 400 Parker Drive, Suite 1110, Austin, TX 78728, United States * Corresponding author, Email: rudy.ghosh@NovaCentrix.com
Resume : The drive to enhance human interactivity and reduce weight of electronic systems has led to the use of non-conventional substrates. As the substrates become thinner, more flexible and economical, the thermal stability of the working substrate is significantly lowered. As such, the conventional modes of component attachment are no longer functional. To bridge this gap, anisotropic adhesives and tapes, as well as low temperature solders and conductive epoxies, have been developed. However, in terms of performance, conventional soldering is still the champion. One way to combine traditional soldering techniques with thermally sensitive substrates is laser soldering. However, technical challenges, combined with the high costs of lasers, continue to create barriers to a broader adoption. This discussion focuses on PulseForge Soldering, which uses high intensity flash lamps to overcome the disadvantages of laser soldering, while enabling soldering on a wide range of substrates. Similar to laser soldering, photonic soldering utilizes selective absorption of light to enable conventional solders (such as SAC-305) to affix commercial packages (such as transistors, LEDs or resistors in traditional sizes) on the underlying thermally unstable substrate (such as PET, PEN or TPU). An innovative application for this process lies in the field of wearables. Sensors and actuators attached to commonly used fabrics could enhance health and wellness monitoring, as well as packaging and fashion.
Authors : Lars Rebohle1,2, Viktor Begeza1, Daniel Blaschke1,4, Jörg Grenzer1, Erik Mehner5, Marcel Neubert3, S. Prucnal1,2, Heidemarie Schmidt4, Wolfgang Skorupa1, Yufang Xie1, Shengqiang Zhou1
Affiliations : 1Helmholtz-Zentrum Dresden - Rossendorf, Institute of Ion Beam Physics and Materials Research, Bautzner Landstraße 400, 01328 Dresden, Germany 2Helmholtz Innovation Blitzlab, Bautzner Landstraße 400, 01328 Dresden, Germany 3Rovak GmbH, Zum Teich 4, 01723 Grumbach, Germany 4Leibniz-Institut für Photonische Technologien, Albert-Einstein-Str. 9, 07745 Jena, Germany 5TU Bergakademie Freiberg, Institut für Experimentelle Physik, Leipziger Straße 23, 09599 Freiberg, Germany
Resume : Flash lamp annealing is, like laser annealing, a non-equilibrium annealing method on the sub-second time scale which excellently meets the requirements of thin film processing: it allows the use of temperature-sensible substrates for thin films, leads to energy and cost savings compared to long-time annealing methods, and enables the formation of new materials in thermal non-equilibrium. Originally developed for microelectronics, flash lamp annealing has opened up new areas of application like thin films on glass, sensors, printed electronics, flexible electronics, batteries etc. In this presentation, we shortly compare the pros and cons of flash lamp and laser annealing for thin film processing and discuss these issues at the example of thin semiconductor films on glass. In detail, the crystallization of amorphous Si on borosilicate glass, the crystallization of amorphous Ge on SiO2/Si substrates, and the formation of NiGe on different Ge substrates (amorphous, polycrystalline and monocrystalline) have been investigated. In all cases, the thin films were deposited by magnetron sputtering, followed by flash lamp annealing. The evolution of microstructure and its electrical properties was traced by corresponding characterization methods such as Raman spectroscopy, transmission electron microscopy, atomic force microscopy, X-ray diffraction, sheet resistance and Hall effect measurements.
Authors : Marcel Neubert1, Lars Rebohle2, Viktor Begeza2, Udo Reichmann1, Georg Ochlich1
Affiliations : 1Rovak GmbH, Zum Teich 4, 01723 Grumbach, Germany 2Helmholtz-Zentrum Dresden - Rossendorf, Institute of Ion Beam Physics and Materials Research, Bautzner Landstraße 400, 01328 Dresden, Germany
Resume : Flash lamp annealing (FLA) is an innovative technology already used in semiconductor industry, for flexible electronics and for thin functional coatings on glass. Due to the short time scale in the milliseconds range, FLA is energy and time effective, suitable for temperature-sensitive substrates and allows the exploitation of non-equilibrium processes. Recently, FLA was combined with sputter deposition to improve the properties and the functionality of transparent conductive binary oxide thin films based on indium, zinc and titanium. In this contribution, we present a new approach assembling both technologies and we report on first experiments to fabricate thin poly-crystalline silicon films on standard glass and ultra-thin glass foils for potential thin film transistor application. However, the improvement of sputtered films by post-deposition treatment is a general issue in order to achieve the desired structural, optical and electrical properties. The functionalization on the millisecond time scale as well as our strategies avoiding thermal stress and minimizing defects in order to obtain layers with a low electrical resistivity are discussed in details.
Authors : Evgeniia Gilshtein, Sami Bolat, Galo Torres Sevilla, Frank Clemens, Thomas Graule, Ayodhya N. Tiwari, Yaroslav E. Romanyuk
Affiliations : Laboratory for Thin films and Photovoltaics, Empa-Swiss Federal Laboratories for Materials Science and Technology, 8600 Duebendorf, Switzerland Laboratory for High Performance Ceramics, Empa-Swiss Federal Laboratories for Materials Science and Technology, 8600 Duebendorf, Switzerland
Resume : Transparent conducting oxides (TCO) are important optoelectronic materials which are typically fabricated by sputtering techniques. Lately, many efforts have been devoted to the fabrication of TCO films by solution-based processes; however, they are still inferior in terms of opto-electrical perfor-mance, and often require high annealing temperatures. Among various TCO materials, indium-tin-oxide (ITO) is the most widely used for different optoelectronic applications such as displays, screens, solar cells, etc. because of its low electrical resistivity in conjunction with a high visible transmittance. Flash Light Annealing (FLA) is an attractive technique used for printed electronics, as the transient heating (1 μs - 10 ms pulse length) could be carried out on a temperature sensitive substrates without affecting them. However, as the emission spectrum of the Xenon lamps used in FLA has a max-imum in the visible region, it is difficult to process films that are optically transparent. In this work, we are proposing integration of an organic coloring agent onto ink-jet printed ITO films before application of the FLA. Because of the increased light absorption, a higher effective temperature can be achieved thus enabling effective sintering of the ITO films. As the result, uniform 250 nm thick ITO film with a sheet resistance below 150 Ω/□ and trans-mittance above 85% can be obtained with FLA. As-fabricated printed and annealed ITO films on glass were employed as transparent capacitive sensors, which can be used to unlock the LCD interface with the help of a touch-sensing mechanism.
Authors : Xubin Chen, Abdessalem Aribia, Matthias Rumpel, Andreas Flegler, Anurag Singhania, Javier B. Bonner, Patrik Hoffmann, Yaroslav E. Romanyuk
Affiliations : Xubin Chen, Abdessalem Aribia, Yaroslav E. Romanyuk: Laboratory for Thin Films and Photovoltaics, Empa - Swiss Federal Laboratories of Materials Science and Technology, Überlandstrasse 129, 8600 Dübendorf, Switzerland; Matthias Rumpel, Andreas Flegler: Fraunhofer Institute for Silicate Research ISC, Neunerplatz 2, 97082 Wuerzburg, Germany; Anurag Singhania, Javier B. Bonner, Patrik Hoffmann: Laboratory for Advanced Materials Processing, Empa, Swiss Federal Laboratories for Materials Science and Technology, Feuerwerkerstrasse 39, 3602 Thun, Switzerland; Patrik Hoffmann: Laboratory for Photonic Materials and Characterization, Ecole Polytechnique Fédérale de Lausanne (EPFL), Station 17, 1015 Lausanne, Switzerland;
Resume : Solid-state thin film batteries are promising power sources for microelectronics. The thin film cathodes in these batteries are typically annealed at about 700 °C in order to crystalize them into electrochemically active phases. This thermal treatment has several drawbacks such as evaporation of Li2O in cathodes at elevated temperatures which degrades the battery performance; need of thermally stable current collectors, e.g. Pt and being time consuming. Therefore, effective alternatives to thermal an-nealing are desired for the crystallization of cathode films. Photonic based methods such as xenon flash lamp annealing (FLA), ultra-violet excimer laser irradiation (UV-laser) and pulsed infrared laser (IR) annealing are shown to crystalize materials used in print-ed electronics and solar cells. In such methods, the thin film material is illuminated with short pulses of light sources and absorbs the photons whose energy is then converted into thermal energy. By these annealing approaches, the cathode films can be crystalized at apparently lower temperature in short time while the underlying current collect and substrate remain unheated. In this work, we explore the feasibility of using FLA, UV-laser and IR annealing for LiCoO2 and LiMn2O4 thin film cathodes. The effect of these methods is systematically compared to that of reference thermal annealing in terms of processing time, crystal structure and electrochemical performance of the cathode films. By certain methods and under optimal conditions, the annealed cathodes are crystalized at room temperature ambient in less than one hour, and showed capacity of up to 51 % of that of thermally annealed samples. A comprehensive comparison of the methods and results will be pre-sented in the talk.
Authors : YANG Fei, ZHU Mingzhi
Affiliations : Institute of Systems Engineering, China Academy of Engineering Physics
Resume : In this work, we report a novel approach to fabricate the nano-hydroxyapatite (nano-HA)/zirconia (ZrO2) ceramic composites via an additive manufacturing process based on mask projection stereolithography (MPSL). The composites suspension characters and photosensitive parameters with different mass proportions of nano-HA/ZrO2 were investigated, the result demonstrated that composites suspension has lesser critical exposure (Ec) and higher penetration depth (Dp) as an increased proportion of HA, which confirms the variation tendency relating to viscosity and refractive index of composites suspension. The prepared green composites with nano-HA/ZrO2 ratio of 75/25 showed a higher density and compressive strength of 3.151g/cm3 and 7.29MP, respectively. The XRD analysis indicated that the nano-HA/ZrO2 composites sample consists of ZrO2 phase and TCP phase after sintered at 1500℃ with the decomposition of HA, still retaining the biocompatibility. Finally, test results illustrated the nano-HA/ZrO2 composites with the ratio of 75/25 have excellent manufacturing performance and microstructure to solve the manufacturing difficulty of conventional ceramic-shaping methods. The study may be referable for fabrication of other ceramic composites.
Laser processing techniques and applications II : D. Grojo
Authors : F. Garrelie1*, A. Abou Saleh1, A. Rudenko1, L. Douillard2, X. Sedao1, S. Reynaud1, F. Pigeon1 and J.P. Colombier1
Affiliations : 1 Univ Lyon, UJM-Saint-Etienne, CNRS, Institut d Optique Graduate School, Laboratoire Hubert-Curien UMR5516, F-42023, Saint-Etienne, France 2 CEA IRAMIS SPEC Service de Physique de l’Etat Condensé, UMR CNRS 3680, Université Paris Saclay, F-91191 Gif sur Yvette, France * Presenting author
Resume : The understanding of the light coupling process on a surface irradiated by ultrafast laser is the most promising strategy to address a nanoscale control of surfaces topographies. Ultrafast optical scattering by the surface is governed by the local nano-roughness and the mutual response of the nanostructures through both radiative and non-radiative fields interaction. The roles of collective effects and inter-pulse feedback on the resulting surface topographies are examined in terms of both experimental and 3D numerical approaches to identify the nature of the intriguing self-regulation process. Laser-induced periodic surface structures were realized on Ti samples and photoemission electron microscopy (PEEM) with a spatial nm resolution was employed for imaging the ultrafast laser light distribution on the pre- structured surfaces. Periodical distributions of light were progressively observed with a frequency shift as the number of applied pulses increases. Concentrated hot-spot patterns were revealed to be superposed to this expected periodic absorption, with the demonstration that nanostructures periodicity reducing is driven by the concentration of the local-field enhancement centers. Self-organization of matter on ultrashort laser-excited surfaces is a complex multiscale phenomenon, implying dynamic coupling between incoming coherent light and evolving material, driven out-of-equilibrium. A new way towards efficient fabrication of surface periodic nanostructures will be presented with the evidence of direct sub-100 nm arrays of nanostructures. A. Abou Saleh et al., ACS photonics 6, 9, pp 2287-2294 (2019) X. Sedao et al., ACS photonics 5, pp. 1418 (2018). A. Rudenko et al., Nanophotonics 8, pp. 459, (2019).
Authors : Alberto Sciuto, Ioannis Deretzis, Giuseppe Fisicaro, Salvatore Francesco Lombardo, Maria Grazia Grimaldi, Karim Huet, Benoit Curvers, Bobby Lespinasse, Armand Verstraete, Antonino La Magna
Affiliations : Dipartimento di Fisica e Astronomia, Università di Catania and CNR-IMM; CNR-IMM; CNR-IMM; CNR-IMM; Dipartimento di Fisica e Astronomia, Università di Catania; LASSE laser systems and solutions of Europe; LASSE laser systems and solutions of Europe; LASSE laser systems and solutions of Europe; LASSE laser systems and solutions of Europe; CNR-IMM
Resume : Laser thermal annealing (LA) is integrated, as micro- and nano- electronics processing step, when strongly confined heating is needed in the semiconductor device manufacturing flows. One of the main challenges for the application of the process in future devices is to achieve an optimal process control. That is why a reliable simulation of the process is needed, and despite models of LA have been implemented in academic or commercial packages, a further evolution of the methods is necessary for the general application in complex structures with nm wide elements where the thermal transport could be dominated by phonon effects. Moreover, ultra-fast (explosive) phase transitions occurs during the irradiation of device elements and their modelling is a challenging objective for the LA simulators’ development. In this context we integrate phonon transport corrections and modeling of explosive crystallization to our existing simulation tool, LIAB (LASSE Innovation Application Booster) that will help us to reproduce experimental data and predict behavior of semiconductor structures upon laser annealing. About the phonon corrections we simulated thermal transport induced by conventional and laser annealing in various structures comparing the results in which standard conditions and corrections were applied, noticing that there is a size dependent discrepancy between standard and corrected solutions. Regarding explosive crystallization we successfully simulated this challenging behavior including secondary melting during the process. The code we developed uses the FEniCS computing platform for solving continuum fields evolution and Gmsh as 3D finite element mesh generator.
Authors : Shengqiang Zhou
Affiliations : Helmholtz-Zentrum Dresden-Rossendorf, Institute of Ion Beam Physics and Materials Research, Dresden, 01328, Germany
Resume : Doping allows us to modify semiconductor materials for desired electrical, optical and magnetic properties. Ion implantation followed by annealing is a well-established method to dope Si and Ge. This approach has been maturely integrated with the IC industry production line. However, being applied to hyperdoping where the dopant concentration is much beyond the solid solubility, the annealing duration has to be shortened to millisecond or even nanosecond. Pulsed laser provides a unique processing method to recrystallize ion-implanted semiconductors. The molten layers undergo a fast cooling and recrystallize epitaxially on the beneath semiconductors with the time duration less than micro-second. In this process, the foreign impurities have limited diffusion time and can be effectively trapped into the lattice sites, leading to doping well beyond solid solubilities. In this talk, we propose that ion implantation combined with pulsed laser melting in nanosecond can be a versatile approach to fabricate hyperdoped semiconductors. The examples include magnetic semiconductors [1-5], Ge1-xSnx , chalcogen doped Si [7-9] as well as aligned nanostructrues .  M. Khalid, et al., Phys. Rev. B 89, 121301(R) (2014).  S. Zhou, J. Phys. D: Appl. Phys. 48, 263001(2015).  S. Prucnal, et al., Phys. Rev. B 92, 222407 (2015).  Y. Yuan, et al., ACS Appl. Mater. Interfaces, 8, 3912 (2016).  Y. Yuan, et al., Phys. Rev. Mater. 1, 054401 (2017).  K. Gao, et al., Appl. Phys. Lett.,105, 042107 (2014).  S. Zhou, et al., Sci. Reports 5, 8329(2015).  M. Wang, et al., Phys. Rev. Applied. 10, 024054 (2018).  M. Wang, et al., Phys. Rev. Applied. 11, 054039 (2019).  Y. Yuan, et al., Phys. Rev. Mater. Phys. Rev. Mater. 2, 114601 (2018).
Authors : M. Prudent *(1), F. Bourquard (1), A. Borroto (2), J.F. Pierson (2), F. Garrelie (1), J.P. Colombier (1)
Affiliations : (1) Univ Lyon, UJM-St-Etienne, CNRS, Institute of Optics Graduate School, Laboratoire Hubert Curien UMR 5516, F-42023 Saint-Etienne (2) Institut Jean Lamour, UMR CNRS 7198, Département CP2S, Ecole des Mines, F-54042 Nancy Cedex, France * lead presenter
Resume : Bulk and thin film metallic glasses (MG) are considered valuable materials for niche markets in various domains such as biomedical, aeronautic and renewable energies. Their amorphous structure induces outstanding mechanical properties (Metal-like) and surface state (Glass-like). The objective is to explore the potential to modify the surface physico-chemistry for the enhancement of the MG functionalities. Ultrafast laser irradiation treatment can considerably increase the properties of the thin film coatings by creating surface structures named LIPSS (Laser Induced Periodic Surface Structures). Controlling the initiation and the positive feedback by adjusting the laser parameters (fluence, pulse number), femtosecond (fs) laser irradiation generates LIPSS with a large variety of scales and periodicities. Under a controlled irradiation, MG undergo a remarkable self-organization process exhibiting very regular and homogeneous patterns with few bifurcations. In this study, Zr-Cu thin film MG was irradiated by a fs laser in order to structure the surface by tailoring multiscale patterns and topographical architectures. Two main types of nanostructures with variation of contrast and periodicity are obtained and analyzed by microstructural characterizations such as SEM, AFM and TEM. These results obtained on binary alloys propose irradiation strategies to achieve surface functionalization of thin film MG improving physico-chemical features such as wettability and corrosion behavior.
Authors : M. Vinnichenko (1), S. Mosch (1), V. Sauchuk (1), N. Trofimenko (1), M. Fritsch (1), M. Kusnezoff (1), I. Mönch (2), R. Illing (2), G.S.C. Bermúdez (2), D. Makarov (2)
Affiliations : (1) Fraunhofer IKTS, 01277 Dresden, Germany (2) Helmholtz-Zentrum Dresden-Rossendorf e.V., 01328 Dresden, Germany
Resume : The present work is focused on the realization of fully printed magnetic field sensors using a cost efficient commercially available material showing the magnetoresistive (MR) effect. The main challenge of this approach is the absence of the electrical conduction and MR-response of as-printed structures because particles of this material are easily oxidizing and are covered by organics directly after printing. To address this issue, we tested the functionalization of the printed material in air on the millisecond time scale using microoptically optimized diode laser array operating in the near infrared spectral range. The energy input on the millisecond time scale is desirable since such treatment simultaneously evaporates organics, enables particles sintering without their further oxidation and ensures the compatibility of the process with thermally sensitive substrates. For these experiments, the paste was formulated based on a commercially available material and sensor structures were screen-printed on various substrates ranging from rigid (alumina, glass) to flexible (polymer foils, paper) ones over inkjet or screen printed Ag electrical contacts. To realize electrically conductive structures revealing MR effect on different substrates, the optical power density and the dwell-time were varied in a broad range. Resulting sensors exhibit electrical resistances in the range of 100 Ohm, show isotropic sensitivity and MR effect typically up to 6% at 500 mT. In contrast to the laser processing, the conventional thermal treatment even in an inert gas mixture did not enable proper electrical conductivity and MR functionality.
Authors : P. Sopeña (1,3), J. Sieiro (2,3), J.M. López-Villegas (2,3), P. Serra (1,3), J.M. Fernández-Pradas (1,3)
Affiliations : (1) Department of Applied Physics, Universitat de Barcelona, Martí i Franquès 1, 08028, Barcelona, Spain; (2) Department of Electronics and Biomedical Engineering, Universitat de Barcelona, Martí i Franquès 1, 08028, Barcelona, Spain; (3) Institute of Nanoscience and Nanotechnology (IN2UB), Universitat de Barcelona, Av. Diagonal 645, 08028, Barcelona, Spain
Resume : Paper is a low cost and sustainable material that is gaining interest as substrate for printing electronic components and circuits. Inkjet printing is the most widespread direct-write method for printing electronics. In spite of its extended use, not all paper substrates are suitable for conductive inkjet printing inks. These exhibit low viscosity and nanometric loading particles that results in ink leakage and non-functional pads when deposited on regular paper such as paper sheets. Owing to this fact, paper must be coated with planarization polymer layers, despite this is less cost-effective and ecofriendly. As an alternative, we propose using laser-induced forward transfer (LIFT) for printing commercial conductive screen printing inks, which high viscosity and large particle size should avoid leaking and result in functional conductive patterns on regular paper. In this work we printed a silver screen printing ink on both coated and regular paper by means of LIFT. We first determined the optimum printing parameters (pulse energy, spot separation) to obtain continuous lines. Then, we considered a multiple-printing approach to increase the electrical performance, resulting in tens of microns thick lines with sheet resistances of 25 mΩ/sq. This value significantly improves sheet-resistance values of elements printed by inkjet and can be obtained even on regular paper. Finally, we printed a RF inductor as a proof-of-concept, which operates accordingly to the design parameters.
Authors : Marina Makrygianni (a), Filimon Zacharatos (a), Dimitris Reppas (b), Nikos Oikonomidis (b), Christos Spandonidis (b), Ioanna Zergioti (a)
Affiliations : (a) National Technical University of Athens, Physics Department, Zografou, 15780, Athens, Greece (b) Prisma Electronics SA, Alexandroupolis, 68 132, Greece
Resume : Current challenges in printed circuit board (PCB) assembly and IC packaging technology involve high resolution for ultra-fine pitch components (<0.3 mm and <60 μm respectively), high throughput and compatibility with flexible substrates. These challenges are poorly met by the conventional deposition techniques (e.g. slot die coating and stencil printing), thus the need for a digital and high-resolution deposition technology is essential. Laser-Induced Forward Transfer (LIFT) constitutes an excellent alternative for assembly and packaging of electronic components: it is fully compatible with the widely used soldering materials, it is environmentally friendly and offers versatile control over the printed solder paste volume with high resolution (< 50 μm) and throughput (up to 10000 pads/s). In this work, a novel process for printing lead-free, jettable solder paste (powder size 15-25 μm; metal loading 87%) relying on LIFT is reported. A side-view imaging configuration is employed by coupling a LIFT setup with a high-speed camera for the real-time visualization of the ejection process. The experimental data from the captured videos are analyzed to determine morphological aspects, such as the volume of the printed pattern. Transfers are achieved with diameters ranging from 50 to 150 μm and printed volumes down to sub-nl. Finally, the reported process is applied for the actual assembly of a 0.22 mm ultra-fine pitch BGA IC on FR4 type PCBs, resulting in functional demonstrators.
Authors : A. O. Larin, A. Nominé, E. I. Ageev, J. Ghanbaja, L. N. Kolotova, S. V. Starikov, S. Bruyère, T. Belmonte, S. V. Makarov, D. A. Zuev
Affiliations : Department of Nanophotonics and Metamaterials, ITMO University; Department of Nanophotonics and Metamaterials, ITMO University and Institut Jean Lamour - CNRS - Université de Lorraine; Department of Nanophotonics and Metamaterials, ITMO University; Institut Jean Lamour - CNRS - Université de Lorraine; Institut Jean Lamour - CNRS - Université de Lorraine; Joint Institute for High Temperatures, Russian Academy of Sciences and Moscow Institute of Physics and Technology; Joint Institute for High Temperatures, Russian Academy of Sciences and Ruhr-Universität Bochum; Institut Jean Lamour - CNRS - Université de Lorraine; Institut Jean Lamour - CNRS - Université de Lorraine; Department of Nanophotonics and Metamaterials, ITMO University; Department of Nanophotonics and Metamaterials, ITMO University
Resume : Plasmonic sponges are of interest in the field of nanophotonics due to the possibility of generating high local field enhancement through the large surface-to-volume ratio. One of the modern vectors for the development of this topic is the combination of a plasmonic nanosponge with semiconductor and all-dielectric materials, which is a rather non-trivial task. In this work, we suggest an application of the femtosecond laser ablation technique for fabrication of hybrid metal-dielectric nanostructures and an effect of laser annealing on them. Laser ablation of a bi-layer Au-Si film allows to obtain structures of plasmon gold nanosponges, the pores of which are filled with grains of crystalline silicon. TEM imaging is showed that diameters of sphere-like structures vary in the range of hundreds of nanometers and a silicon phase is crystalline. Numerical calculations of the electric field distribution in a hybrid nanosponge showed the possibility of the electric field enhancement in a wide range of wavelengths. We have demonstrated that such a structure can generate photoluminescence in a visible and near-infrared spectral range under multiphoton excitation. In addition, the positive effect of laser annealing on the photoluminescence generation of silicon is shown, which is accompanied by an increase in the peak of the optical phonon of crystalline silicon in Raman spectra and a general increase in the intensity of the photoluminescence signal from the nanostructure under identical excitation conditions. It is possible to find an application of hybrid nanosponges for the development of nanoscale sources of broadband radiation and for the modernization of the broadband scanning near-field microscopy.
Authors : Kuo Yao-Jen, Henry Medina, Yu-Ze Chen, and Yu-Lun Chueh
Affiliations : Department of Material Science and Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan; Department of Electronic MaterialsInstitute of Materials Research and Engineering (IMRE)Agency for Science, Technology and Research (A*STAR)Singapore 138634, Singapore; Department of Material Science and Engineering, National Cheng Kung University; Department of Material Science and Engineering, National Cheng Kung University
Resume : Layared materials such as graphite and transition metal dichalcogenides have attracted lots of attention owing to their unusal nature of reacing atomic thickness. These so-called two-dimensional materials reveal outstanding physical properties when its thickness reduces to mono layer, such as indirect to direct bandgap transition for TMDs, which is ideal for different kinds of potential applications in optoelectronics, energy harvesting, Li-ion batteries and supercapacitors. Among the numorous TMDs, MoTe2 is the only TMD, which can be synthesized in two phases because of the small energy difference between them. However, the synthesis approach to control these two phases is not refined enough. Most reliable strategy is CVD process, but its require high temperature annealing for a long time while control the Te atomphere at the same time. These complicated process is hard to applied and high temperature also restrict the use of substrates. Therefore, further improvement of the synthesis methods is an important issue. Here, we use a laser approach to induce the MoTe2 growth directly on different substrates such as Quartz and sapphire and so on. We control the two phases by tuning the laser power and irradiation time. TEM supported by Raman and X-ray Photoelectron Spectroscopies confirm the existence and quality of the synthesized films. Furtheremore, this approach can be extended to the synthesis of other TMDs. The laser annealing assisted method develops a new approach that is fast, cheap, patternable and does not require transfer giving a step forward on the technology development for practical applications.
Authors : L. Lavisse1, C Schuman2, C. Gorny3, P. Mathieu1, A. Kanjer1, Q. Freville2, H. Libang2, P. Berger4, O. Heintz1, V. Optasanu1, P. Peyre3, T. Montesin1, M. C. Marco de Lucas1, A. Tidu2
Affiliations : 1Laboratoire Interdisciplinaire Carnot de Bourgogne (ICB), UMR 6303 CNRS-Universite´ Bourgogne-Franche Comte, 9 Av. A. Savary, BP 47 870, F-21078 DIJON Cedex, France 2LEM3, Université de Lorraine, CNRS, Arts et Métiers ParisTech, Metz , France, 3Laboratoire PIMM, Ensam, CNRS, Cnam, HESAM Universite, 151 Boulevard de ´ l’Hopital, 75013 PARIS, France 4NIMBE, CEA, CNRS, Université Paris-Saclay, CEA Saclay 91191 Gif sur Yvette Cedex
Resume : In previous works [1,2] it was proved that Laser Shock Peening (LSP) improves the high temperature (HT) oxidation resistance of pure Ti. Here, we address the understanding of this behaviour as the result of the different effects of the LSP treatment affecting both the surface and the volume of the metal. For this, the study was focused on the influence of the laser irradiance (varying around 9 GW/cm2), and the number of laser impacts (1 to 3). A microstructural study of the cross-section of the LSP treated samples was made by EBSD as a function of these parameters. Two types of twins are observed, with a specific location within the samples depth. Their density increases with the laser irradiance and number of impacts. The LSP treatment modifies the topography of the samples surface. Moreover, XRD results showed changes in the texture at the subsurface. Chemical modifications of the surface as a function of the laser irradiance were investigated by XPS and SEM/EDS. It was shown an increase of the surface contamination with the irradiance and number of impacts. The chemical environment during the HT oxidation was first studied by XPS and the results were further compared with those obtained by ion beam analysis. This shows a preferential location of nitrogen at the metal/oxide interface from the very beginning (up to 100 h) of oxidation. This insertion of nitrogen seems to play a role of barrier for oxygen diffusion. In addition, the twins produced by the LSP treatment can also contribute to a smaller penetration of oxygen within the metal . Finally, the best LSP parameters are those limiting the chemical contamination of the sample and maximizing the structural modifications. Ref  A. Kanjet et al. Surf. Coat. Tech., 2017  A. Kanjer et al. Oxid. Met., 2017
Authors : Dab Chahinez, Sven Otto, Joe P. Harris, Andreas Ruediger, Katja Heinze and Christian Reber
Affiliations : Dab Chahinez; Joe P. Harris;Christian Reber : Université de Montréal, département de chimie, Montréal, Canada; Sven Otto;Katja Heinze : Johannes Gutenberg University, Germany; Andreas Ruediger: Institut national de la recherche scientifique, Nanophotonique, nanoélectronique. Centre Énergie Matériaux, Varennes, Canada.
Resume : Raman and Tip-Enhanced Raman Spectroscopies (TERS) are very powerful techniques to investigate the electronic and molecular structure of nanoscale materials. First, we report on photochemical and photophysical properties produced by Surface Plasmon Resonance (SPR) on metallic nanograins by means of high resolution (TERS). We describe the local variation of plasmon-induced Raman enhancement on the surface of nanostructure that also affects the photochemistry near the functionalized tip apex. Our TERS maps with 10 nm spatial resolution show Raman modes of hot electron reduction of 4-nitrothiophenol molecules on the tip and indicate at least partial photochemical dimerization. An apparent photo-induced reversibility of this dimerization can be conservatively explained by a local topography feature that we simulate in a finite element environment. Second, we have studied the surprising pressure effects on luminescence spectra of a series of molecular chromium(III) complexes and compare with the well-established properties of doped solids. Luminescence and Raman spectra and their variation with external pressure are presented. The pressure-induced red shift of 11 cm 1/kbar in [Cr(bpy)3]3 and similar molecular compounds is higher by more than an order of magnitude than for chromium(III) doped oxides, widely applied as pressure sensors.
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Lasers in additive manufacturing II : Andreea MATEI
Authors : Svyatoslav Chugunov1, Andrey Tikhonov1, Oleg Dubinin1, Andrey Smirnov2, Victor Rybalchenko2, Iskander Akhatov1, Igor Shishkovsky1
Affiliations : 1 Skolkovo Institute of Science and Technology, Moscow, Russia 2 Moscow Polytechnical University, Moscow, Russia
Resume : Application of laser stereolithography (SLA) was considered for the manufacture of functional lead-free piezoceramics from barium titanate. The process of layer-by-layer growing of preforms from a slurry consisting of a mixture of particles of barium titanate powder and a solution of photopolymer monomers was experimentally studied. The obtained preform samples were subjected to polymer binder removal processes and subsequent calcination at temperatures of 1100 and 1300 ° С. The microstructure of sintered samples and their phase composition were determined. The possibilities of obtaining billets from barium titanate by the SLA and obtaining sintered material without impurity phases in the composition are shown. The high density and mechanical strength of samples of 3D printed barium titanate ceramics strongly depended from optimal technological route, including the choice of the type and concentration of the monomer solution, the SLA process regimes, temperature-time modes of polymer binder removal and firing.
Authors : C. N. Kuo (a,b,*), P.C. Peng (a), and Y. L. Su (b)
Affiliations : a. Department of Bioinformatics and Medical Engineering, Asia University, Taichung, Taiwan b. 3D Printing Medical Research Institute, Asia University, Taichung, Taiwan
Resume : Development of advanced materials is always an important topic for global researchers. Meanwhile, the function/performance improvement of products is always accompanied by the development of advanced materials, especially the lightweight improvements. One of the advanced lightweight material is Sc- and Zr-modified Al alloy. The high specific strength of such materials is contributed by the precipitation strengthening effect and thus limits the formability through traditional processes. According to the development of 3D printing technologies, numerous mature high specific strength metal materials with complicated design were developed and applied to real applications such as aerospace parts and medical devices. In this study, Selective Laser Melting (SLM) technology has been introduced to fabricate Sc-modified Al alloy. Since the high strength of Sc-modified Al alloy is contributed by the fine grain size and precipitation strengthening effect, the strength can be further improved if the initial grain size can be made finer using 3D printing parameter optimization by exploring the relationship between parameter-microstructure-performance. In this study, the microstructure and mechanical property of 3D printed Sc-modified Al were examined/tested and the relationship between parameter-microstructure-performance was discussed in detail.
Authors : Sweta Rani, Arun Jaiswal, Gaurav Pratap Singh, Sumit Saxena, Boon Mian Teo and Shobha Shukla
Affiliations : Indian Institute of Technology Bombay-Monash Research Academy, Indian Institute of Technology, Mumbai, MH, India - 400076; Nanostructures Engineering and Modeling Laboratory, Department of Metallurgical Engineering and Materials Science, Mumbai, MH, India - 400076; Nanostructures Engineering and Modeling Laboratory, Department of Metallurgical Engineering and Materials Science, Mumbai, MH, India - 400076; Nanostructures Engineering and Modeling Laboratory, Department of Metallurgical Engineering and Materials Science, Mumbai, MH, India - 400076; School of Chemistry, Monash University, Wellington Rd, Clayton, VIC 3800; Nanostructures Engineering and Modeling Laboratory, Department of Metallurgical Engineering and Materials Science, Mumbai, MH, India - 400076.
Resume : Tunable photonic crystals (TPC) are nature-inspired nanostructure whose response can be tuned with an external stimulus. There has been a great demand for such structures because of its wide applications in optically active devices, color displays, biological and chemical sensing. Hydrogel is a potential material for fabrication of TPC as it can exhibit a reversible response to an external stimulus such as humidity and heavy metals. Two-photon assisted polymerization (TPP) provides efficient control over the spatial resolution of fabricated features due to the non-linear laser-material interaction. Subwavelength resolutions can be achieved with ease in photoactive polymeric resin compositions using TPP. We have demonstrated the fabrication of biocompatible hydrogel-based TPC having different periodicities, using a nanoimprinted mold fabricated by TPP. Optical detection was employed to monitor the response of the fabricated TPC in the presence of various humidity levels and different concentrations of heavy metals. This technique provides an efficient way to fabricate TPC for wide range of materials and hence can be used to devise sensors for other stimuli as well. Keywords: Photonic crystals, Hydrogels, Sensor, Direct laser writing.
Laser processing of materials III : Christoph Lienau
Authors : Dirk Hauschild
Affiliations : LIMO GmbH
Resume : Since the beginning of the development of high power diode laser in '80s of the last century, the industrial use of laser sources started a unique success story in scaling power and increasing brightness with diode pumped laser and direct diode laser sources in nearly all fields of applications and industries. On of the key advantages of these diode laser is the electro-optical efficiency of >60% that is higher than any other type laser source. In addition, the range of available wavelengths increased in the past years including 450nm in the visible and 1,9µm in the IR. The power level in the most optimized wavelength range from 900nm to 1070nm can generate today >20W per 100µm emitter and within an array of 19 emitters in a single chip >200W becomes now standard in industry. Parallel to the development of the diode laser technology, new type of micro-optics were developed that enable to combine a large number of emitters into one beam and shape the light of the diode laser arrays to process optimized or even enabling beam profiles and geometries. This talk will give an overview and latest examples how the beam shaped diode laser can be used to bring the right dose of energy to the applications and how to change or even generate new material properties with these laser sources. For the first time, it is possible to address very narrow process and energy windows to select a defined advantageous phase transition of materials or material compositions that can be designed and simulated e.g. in the computer and produced with the selected energy doses of the laser afterwards. This precise material transformation can be applied on small and large surfaces using the above mentioned scaling and beam shaping technologies. With this approach a wide range of challenges can be addressed in consumer electronics, generation and storage of electrical energy and energy efficient smart sensors and devices.
Authors : García-Quiñonez, L.V.*(1), Pineda-Aguilar, N.(2), Cardona-Castro, M.A.(3), Mendivil-Palma, M.I.(2), López-Villegas, R.(1), Coello-Cárdenas, V.M.(1), Rodríguez-Beltrán, R.I.(1), Castillo-Rodríguez, G.A.(4), Gómez-Rodríguez, C.(4).
Affiliations : (1) CONACYT- Centro de Investigación Científica y de Educación Superior de Ensenada, B.C, Unidad Monterrey, México; (2) Centro de Investigación en Materiales Avanzados, S.C. (CIMAV), Unidad Monterrey, México; (3) Centro de Investigación y de Estudios Avanzados del I.P.N., Unidad Saltillo, México, (4) Facultad de Ingeniería Mecánica y Eléctrica (FIME)- Universidad Autónoma de Nuevo León (UANL, México. * García-Quiñonez, L.V.
Resume : In this work, the effects of selective laser sintering on ceramic oxide powders were investigated. Different ceramic oxides (SiO2, Al2O3, ZnO, CaO, MgO, K2O, Na2O, Li2O) were dry mixed and ground in a planetary mill at 250 rpm for 30 min, with higher weight percentage of Al2O3 and CaO. The mixture of ceramic powders was irradiated with a continuous CO2 laser (λ=10.64 μm) with a power density of 155 W/cm2. The powders were irradiated in two ways: fixed irradiation and irradiation on moving samples placed in a translation device with two irradiation scans on the same sample (slow and fast irradiation), which were: 5 - 15 mm/s and 5 - 17 mm/s. The morphology, elemental composition, crystalline structure and thermal properties of sintered ceramic samples were studied by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and thermogravimetric analysis/differential thermal analysis (TGA/DTA). The SEM results, showed that the morphological changes depend on laser parameters, obtaining a sintered surface without porosity formation. XPS results, confirmed the chemical composition and chemical states of the corresponding elements. The XRD results revealed the formation of crystalline phases as anorthite, cordierite and magnesium aluminate spinel. In the thermal studies the formation of new phases was confirmed.
Authors : P. Warnicke1, A. Cavaliere1, A. De Luca2, C. Leinenbach2, and M. Pouchon1
Affiliations : 1. Paul Scherrer Institut, 5232 Villigen, Switzerland; 2. EMPA, Swiss Federal Laboratories for Materials Science and Technology, 8600 Duebendorf, Switzerland
Resume : Oxide dispersion strengthened (ODS) steel is a promising structural material for high-temperature applications such as turbines and advanced nuclear reactors due to its enhanced resistance to irradiation, corrosion, and high-temperature creep. Production of ODS steel via conventional powder metallurgy faces challenges in maintaining uniform properties throughout the material combined with complications and high cost of fabrication. Selective laser melting (SLM) is a rapidly emerging technique that circumvents these problems by systematically melting the powder locally during the buildup. However, SLM involves extreme thermal gradients leading to complex microstructures during cool down influencing the properties of the material. The ODS dispersoids as well as the crystallographic phases present on the microscopic scale determine the macroscopic properties of the material. In this work we characterize the chemical microstructure of ODS steel produced by SLM. Powders produced from mechanically alloyed Fe-9Cr steel with 0.5% yttrium oxide were employed to print a cubic specimen using SLM. Pieces of the 3D printed specimen were formed into thin X-ray transparent thin sections using electro-polishing. Scanning- (SEM) and transmission electron microscopy (TEM) were used to characterize dispersoid morphology and distribution, revealing oxide dispersoids in the steel matrix with sizes down to 2 nm. Focused synchrotron hard X-rays were subsequently used for chemical and crystallographic characterization of the melt pools in the thin section. Understanding the interplay between chemical and crystallographic microstructures is key for optimizing materials manufactured by laser based additive manufacturing.
Authors : M. Novotny1, S. Chertopalov1, P. Fitl1, S. Havlova1,2, J. Fara1,2, J. Bulir1, L. Volfova1, J. More-Chevalier1, M. Poupon1, L. Fekete1, P. Pokorny1, J. Lancok1
Affiliations : 1 Institute of Physics of the Czech Academy of Sciences, Na Slovance 2, 182 21 Prague, Czech Republic 2 University of Chemistry and Technology, Prague, Technicka 5, Prague, Czech Republic
Resume : Fluoride and ZnO based materials occupy an original and strategic position in modern optics and optoelectronics. The fluorides exhibit unique optical features (low phonon energy, high transparency in UV region, suitable host for rare earth ion dopants), which make them excellent candidates for variety of optoelectronics and photonics applications. ZnO material can be utilized in several emerging applications in optoelectronics and sensors because of its properties, ie. good transparency, high electron mobility, and strong room-temperature luminescence. Combinations of these materials in nanostructured films might result in structures of interesting properties with a potential for application in optoelectronics. We demonstrate fabrication of either pure and Eu doped fluorides (CaF2 and LaF3), and pure and Eu doped ZnO nanostructured thin films by means of hybrid laser deposition technique. Pulsed Laser Deposition (PLD) utilizing pulsed Nd:YAG laser operated at 266 nm was used for fabrication of ZnO based material. Fluorides were prepared by Electron Beam Evaporation (EBE). We investigated dependence of morphology, optical and structural properties on mixture ratio of fluoride/ZnO content. Pulsed laser annealing (PLA) utilizing a KrF laser at λ=248 nm was performed to further modify these properties at fluence varied from 10 to 300 mJ/cm2. The effect of PLA on optical properties was characterized in-situ by spectrophotometry and photoluminescence measurements.
Authors : Yu-Jen Hsu, Yung-Tang Nien
Affiliations : Department of Materials Science and Engineering, National Formosa University
Resume : In this study, delafossite CuFe5O8 was prepared by a CO2 laser sintering method and characterized with crystal structure, surface morphology and composition using an x-ray diffractometer (XRD) and a scanning electron microscope (SEM) equipped with an x-ray energy dispersive spectrometer (EDS), respectively. SEM images revealed that the surface of laser-sintered CuFe5O8 can be divided into two parts based on their various cooling rates. The first part scanned by laser beams (valley) exhibits many tiny crystallites with a triangular shape and an average size of around 5 μm. The second part formed between laser scans (peak) presents smaller crystallites with porous structures and an average size of around 1.5 μm. XRD patterns presented a main phase of CuFe5O8 with a small amount of CuFeO2. Selected area electron diffraction patterns revealed that the d-spacing corresponds to the phases of CuFeO2 and CuFe5O8. As known from the phase diagram, a molar ratio of 1:1 for CuO and Fe2O3 precursors would generate a main phase of CuFe2O4. However, in this study, the process of CO2 laser sintering was carried out in ambient air without any gas injection. It is believed that the lasering will deplete the surrounding oxygen content and result in a phase transformation from CuFe2O4 into CuFe5O8. Electrical measurements of laser-sintered CuFe5O8 using two tungsten microprobes indicated a metallic conducting property. The detailed process and characterization will be presented in the conference.
Authors : D. Sola, A.F. Lasagni
Affiliations : Institut für Fertigungstechnik, Technische Universität Dresden, George-Bähr-Str. 3c, 01069 Dresden, Germany; Laboratorio de Óptica, Centro de Investigación en Óptica y Nanofísica, Universidad de Murcia, Campus Espinardo, 30.100 Murcia, Spain; Fraunhofer-Institut für Werkstoff- und Strahltechnik IWS Winterbergstr. 28, 01277 Dresden, Germany.
Resume : The fabrication of diffractive elements in ophthalmic polymers to induce refractive index changes to be applied for refractive correction is of great interest in the field of Optics and Ophthalmology. In this work, silicone hydrogel used for soft contact lenses were structured with linear periodic patterns by means of Direct Laser Interference Patterning (DLIP). As laser sources, a Q-switched laser system emitting 10 ns pulses at a wavelength of 266 nm and a mode-locked solid-state oscillator delivering 12 ps laser pulses at a wavelength of 532 nm were used to produce periodic patterns on the surface of the polymer material. DLIP structuring was carried out employing a two-beam interference setup, studying the features of the laser processed areas as a function of both the laser fluence and the interference period. Next, static water contact angle (WCA) measurements were carried out with deionized water droplets on the structured areas. Contact angle variation was evaluated as a function of time to study the hydration properties of DLIP structures. The topography of the structured areas was investigated using optical confocal microscopy. Compositional and structural modifications on the materials were studied by means of micro-Raman spectroscopy. Finally, periodic patterns were characterized through diffractive techniques to determine the diffractive properties of the DLIP periodic patterns.
Laser Department, 409 Atomistilor Str., 077125 Maguerele - Bucharest, Romaniaandreea.email@example.com
Laboratoire IRCER / UMR CNRS 7315; Centre Européen de la Céramique (CEC), 12 rue Atlantis, 87068 Limoges, Francecatalin.firstname.lastname@example.org
Fraunhofer IKTS, Winterbergstr. 28, 01277 Dresden, Germanymykola.email@example.com
Institute of Materials Science and Engineering, Gustav-Kirchhoff-Str. 5, 98693 Ilmenau, Germanypeter.firstname.lastname@example.org