Advanced Materials Synthesis, Processing and CharacterizationEE
Protective coatings and thin films
Protective coatings and thin films is a biannual symposium that has started in 1993. For 2015, highlights will focus on advances in thin film synthesis using plasma processes and on the characterization of nanostructured coatings. Particular emphasis will be placed on the development of new thin films for mechanical, biological and energy applications.
Today, thin film technology is widely used in industrial applications. However, the development of new products requires coatings with improved properties of coatings and/or to synthesize new materials in thin film form. Processes using plasma at either atmospheric or low pressure are well suitable to achieve these goals. This symposium will be dedicated to advanced methods of vapor deposition and surface functionalization treatments and to nanoscale methods of coatings characterization. Areas of particular interest will include, but will not be limited to, the following topics:
- Fundamentals of deposition processes, growth modeling, plasma-surface interactions and in situ diagnostics
- New deposition processes including the recent development on HIPIMS technology or on the use hybrid methods combining for instance arc evaporation and magnetron sputtering or PVD and CVD, atmospheric plasma
- Nanostructured coatings including nanocomposites, multilayers and nanolayers
- Correlation of microstructure and functional properties such as optical, thermoelectrical, thermochromic, magnetic, etc
- Hard, wear and oxidation resistant coatings
- Characterization methods to determine the properties of the films in their conditions of use (high temperature, high pressure, irradiation, gaseous environment…)
- New materials in thin film form: high entropy alloys, oxynitrides, intermetallics…
We call for communications giving the latest information on research and development in topics corresponding to one or more of the above-mentioned areas.
Hot topics to be covered by the symposium:
- Fundamentals of thin film growth: diagnostics and modeling
- In situ and real-time diagnostics during film growth and surface modification
- High Power Impulse Magnetron Sputtering processes
- Atmospheric processes - organic synthesis and surface functionalization
- Composition-properties relations in multi-component and nanostructured functional films
- Characterization methods at the nanoscale
- Corrosion and oxidation resistant coatings
- Low-friction, self-healing and wear resistant hard coatings
- Design of novel thin films for energy conversion, save and storage
- Coatings for biological applications
Confirmed invited speakers:
- Roger Smith, Loughborough University, UK
Atomistic models of sputtering and thin film growth over realistic time scales
- Abdou Djouadi, CNRS-University of Nantes
In situ characterization using mass spectrometry: Cr, CrN, CrSiN, Al films
- Alexander Kromka, Institute of Physics of the ASCR, CzechRepublic
Nanostructured Diamond Coatings with Enhanced Functions in Electronics and Life Sciences
- Rainer Cremer, KCS Europe, Germany
- Bojan Podgornik, Institute of Metals and Technology, Slovenia
Performance of DLC and CrN coatings under oil lubricated conditions
- Philipp Dale, University of Luxembourg, Luxembourg
Kesterite for earth abundant photovoltaics: can we make single phase thin films, and does it matter?
- Filipe Vaz, University of Minho, Portugal
- Samir Aouadi, University of North Texas, US
Layered Binary Metal Oxide Solid Lubricants for High Temperature Moving Assemblies
- David Mariotti, University of Ulster, UK
Atmospheric pressure plasmas: from nano-synthesis and surface engineering to photovoltaic devices
The manuscripts submitted to the symposium will be published in the journal ‘Surface and Coatings Technology' by Elsevier after a standard peer-review processing.
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Authors : Yann Almadori*, Łukasz Borowik*, Nicolas Chevalier*, Denis Mariolle*, Stefano Curiotto**, Fabien Cheynis**, Frédéric Leroy**, Pierre Müller**, Jean Charles Barbé*
Affiliations : *Univ. Grenoble Alpes, F-38000 Grenoble, France CEA, LETI, MINATEC Campus, F-38000 Grenoble, France ; **Centre Interdisciplinaire de Nanoscience de Marseille (CINaM) CNRS UMR 7325, Aix-Marseille Université, Case 913 Campus de Luminy, 13288 Marseille Cedex 9, France
Resume : The dewetting of ultrathin silicon layers, induced by the thermal budget, is an issue to develop SOI-based technology. However, dewetting can be controlled to obtain well-arranged agglomerates with similar size or even inhibited. This experimental study aims at demonstrating the effect of the strain, surface contamination, ion sputtering on the dewetting mechanism, and also different ways to inhibit the dewetting process. For that purpose, we present the results obtained on (001) oriented ultrathin (8-22 nm) silicon layers on silicon dioxide (SOI). Both stress-free and strained (s-SOI) films fabricated using the Smart cut process have been studied. In order to understand the dewetting mechanism, samples were heated up to ~800°C under ultra-high vacuum (1×10-9 mBar) during tens of minutes, and characterized in situ by Low Energy Electron Microscopy (LEEM) by Atomic Force Microscopy (AFM). We will present the review of methods to control dewetting process developed in our group: -firstly, clear evidences of the influence of strain on the size, shape and density of these Si agglomerates formed during dewetting -secondly, control of dewetting by initial surface contamination through formation of SiC nanodots -thirdly, the influence of argon ion sputtering by control of ratio between amorphous and crystalline silicon -finally, inhibition of dewetting by control of crystallographic orientation of dewetting front or by exposing the Si surface to a partial pressure of dioxygen.
Authors : D. Edström, D.G. Sangiovanni, V. Chirita, L. Hultman, I. Petrov* and J. E. Greene*
Affiliations : Thin Film Physics, IFM, Linköping University, Sweden * University of Illinois, Departments of Materials Science and the Materials Research Laboratory, USA
Resume : The Modified Embedded Atom Method (MEAM) interatomic potential within the classical Molecular Dynamics (MD) framework enables realistic, large-scale simulations of important model materials such as TiN. As a step toward understanding atomistic processes controlling the growth of TiN on a fundamental level, we perform large-scale simulations of TiN/TiN(001) deposition using a TiN MEAM parameterization which reproduces experimentally-observed surface diffusion trends, correctly accounts for Ehrlich barriers at island step edges, and yields results in excellent qualitative and good quantitative agreement with Density Functional Theory (DFT) based Ab Initio MD. Half a monolayer of TiN is deposited on 100x100 atom TiN(001) substrates at a rate of 1 Ti atom per 50 ps, resulting in simulation times of ~ 200 ns. The TiN substrate is maintained at a typical epitaxial growth temperature, 1200 K during deposition using Ti:N flux ratios of 1:1 and 1:4 with incident atom energies of 2 and 10 eV to probe the effects of N2 partial pressure and substrate bias on TiN(001) growth modes. We observe nucleation of TixNy molecules; N2 desorption; the formation, growth and coalescence of mixed <100>, <110>, and <111> faceted islands; as well as intra- and interlayer mass transport mechanisms. For equal flux ratios at 2 eV incidence energy, islands begin to form atop existing islands at coverages ≳ 0.25 ML, leading to 3D multilayer growth. At 10 eV, the film growth mode shifts toward layer-by-layer growth. We discuss the implications of these results on thin film growth and process tailoring.
Authors : V. Elofsson1, M. Saraiva2, R.D. Boyd3, and K. Sarakinos1
Affiliations : 1Nanoscale Engineering Division, Department of Physics, Chemistry and Biology, Linköping University, SE- 581 83 Linköping, Sweden 2Sandvik Coromant AB, SE-126 80, Stockholm, Sweden 3Plasma and Coatings Physics Division, Chemistry and Biology, Linköping University, SE- 581 83 Linköping, Sweden
Resume : To explain the origin and predict the type of biaxial texture in off-normally deposited films, Mahieu et al. [Thin Solid Films 515, 1229 (2006)] have developed an analytical model that, for certain materials, predicts the occurrence of a double in-plane alignment. However, experimentally only a single in-plane alignment has been observed and the reason for this discrepancy has been unknown. The model calculates the resulting in-plane alignment by only taking into account grains with a specific out-of-plane orientation. This overlooks the fact that in vapor condensation experiments where growth kinetics is limited and only surface diffusion is active, out-of-plane orientation is random during grain nucleation and orientation selection happens only upon grain impingement. In the present study we pre-determine the out-of-plane orientation and only allow for competitive growth with respect to the in-plane alignment by growing a Cr film off-normally on a suitable fiber textured Ti epilayer. Crystallographic analysis shows unambiguously a biaxially textured Cr (110) film that possesses a double in-plane alignment, in agreement with predictions of the in-plane selection model by Mahieu et al. Thus, a long standing discrepancy in the literature is resolved, paving the way towards more accurate theoretical descriptions and hence knowledge-based control of microstructure evolution in biaxially textured thin films.
Authors : B. Baudrillart, F. Bénédic, A. Soltani, F.J. Oliveira, R.F. Silva, J. Achard
Affiliations :  Université Paris 13, Sorbonne Paris Cité, LSPM-CNRS, 99 Avenue Jean-Baptiste Clément, 93430 Villetaneuse, France ;  Institut d'Electronique de Microélectronique et de Nanotechnologie (IEMN) CNRS, PRES Université Nord de France, Université de Lille1, Avenue Poincaré, Cité scientifique, F-59650 Villeneuve d'Ascq, France ;  CICECO, Department of Ceramics and Glass Engineering, University of Aveiro, 3810-193 Aveiro, Portugal
Resume : Many thermal, electrical and mechanical applications of diamond films require large area thin layers deposited on various substrates at compatible temperature typically bellow 400 °C . We investigate a new distributed antenna array PECVD system, with 16 microwave plasma sources arranged in a 2D matrix, which enables the growth of 4-inch diamond films at low-pressure (0.2-0.6 mbar) and low substrate temperature (300-500 °C), by using H2/CH4/CO2 gas chemistry . Such a system allows reaching plasma density as high as 10^12 cm-3 , which leads to an efficient chemical species production. The effects of growth parameters are investigated both on diamond film properties (morphology, growth rate, thickness homogeneity, electrical properties, adhesion ) and plasma features (distribution of electron and species densities, temperatures, absorbed microwave power ). Experimental study points out that, depending on growth conditions, the diamond film features evolve from nanocrystalline to microcrystalline. 2D Plasma modelling evidences a gas temperature below 1100 K, an electron density around 10^12 cm-3 and a high conversion of molecular hydrogen H2 in atomic hydrogen H close to the plasma sources.  J.J. Gracio et al., J. Phys. D: Appl. Phys. 43 (2010) 374017.  H-A. Mehedi et al., Diamond Relat. Mater. 47 (2014) 58.  L. Latrasse et al., Plasma Sources Sci. Technol. 16 (2007) 7.
Authors : G. Abadias (1), Ph. Djemia (2), L. Belliard (2), V. Uglov (3), M.B. Kanoun (4), V. Ivashchenko (5)
Affiliations : 1. Institut Pprime, Université de Poitiers-CNRS-ENSMA, France; 2. LSPM-CNRS, Université Paris 13, France; 3. Belarusian State University, Minsk, Belarus; 4. School of Physics, Georgia Institute of Technology, Atlanta, USA; 5. Institute of Problems of Material Science, NAS of Ukraine
Resume : Since the pioneering materials selection concept of Holleck  to design multi-component hard coatings, efforts have been made to synthesize new ternary or multinary transition metal nitride (TMN)-based alloys, which offer the possibility of fine tuning the mechanical and physical properties by an appropriate choice of metal or non-metal alloying elements and by optimizing deposition process parameters. We will present a synthetic overview on the effect of alloying elements like Ta, Zr or Al on the phase stability, structure, stress state and elastic properties of a wide range of TMN thin films. Ternary Ti-Zr-N, Ti-Ta-N and Ta-Zr-N alloys will be first discussed based on ab-initio calculations and thin film growth experiments on polycrystalline films deposited by reactive magnetron sputtering [2-3]. Then, recent results obtained on quaternary TiZrAlN films will be presented. The stress state was investigated using both in situ (wafer curvature) and ex situ (XRD) techniques. The transverse and longitudinal sound velocities were determined by Brillouin Light scattering (BLS) and picoseconds acoustics (PA), while the hardness was measured by nanoindentation. The influence of phase composition, crystal structure, preferred orientation and film morphology on the elastic and mechanical properties will be discussed.  H. Holleck, J. Vac. Sci. Technol. A 4, 2661 (1986)  G. Abadias, Ph. Djemia, L. Belliard, Surf. Coat. Technol. 257 (2014) 129  G. Abadias, M.B. Kanoun, S. Goumri-Said et al., Phys. Rev. B 90 (2014) 144107
Poster session : J.F. Pierson & M. Cekada
Authors : Marta Janusz-1, Lukasz Major-1, Juergen M. Lackner-2, Jerzy Morgiel-1
Affiliations : 1). Institute of Metallurgy and Materials Science; Polish Academy of Sciences, Cracow, Poland 2). JOANNEUM RESEARCH- Materials- Institute for Surface Technologies and Photonics, Niklasdorf, Austria
Resume : The use of carbon fiber composites (CFC) for different applications is widespread. Carbon-based materials show, however, significant oxidative degradation in air. For the protection of CFC it was necessary to apply coatings on the composite surface. In the presented paper, as the inner part chromium/ chromium nitride (Cr/CrN) multilayer structure has been selected. The outer part of the coating, in the presented work, was hydrogenated amorphous carbon (a-C:H) gradually implanted by Cr nanocrystals. Coatings were prepared using magnetron sputtering technique. The application of transmission electron microscopy indicated that proposed deposition method allowed to form Cr/CrxN multilayer of lambda= 150 nm topped with a-C:H+ Cr23C6 composite of varied carbides density. The micro- hardness of the deposited coatings was up to 14GPa (at loading of 2 and 5mN).
Authors : G. Abadias (1), Ph. Djémia (2), D. Faurie (2)
Affiliations : 1. Institut Pprime, Dpt. Physique et Mécanique des Matériaux, Université de Poitiers - CNRS - ENSMA, 86962 Chasseneuil-Futuroscope, France; 2. Laboratoire des Sciences des Procédés et des Matériaux, CNRS - Université Paris 13, 93430 Villetaneuse, France
Resume : Transition metal nitrides have been extensively studied in the last decades, owing to their excellent performance as hard, wear- and corrosion resistant coatings and recently as reflecting back contacts and barrier film in solar cells. For most of the applications, the thermal stability and the subsequent high-temperature mechanical properties are of great interest. The effect of temperature on thin film elastic constants can be studied by high-temperature acoustic measurements. Here, we propose to use in situ Brillouin light scattering (BLS) laser-based technique during vacuum annealing up to 1200°C to measure the temperature-dependence of the sound velocity of a few kind of surface acoustic waves in TiZrN thin films. Binary TiN and ZrN films, as well as ternary TiZrN film, with thickness > 300 nm, were deposited by reactive magnetron sputtering at 600°C on MgO (001) single-crystal substrates. X-ray diffraction pole figures evidence a cube-on-cube epitaxial growth for all films. The in-plane and out-of-plane lattice parameters were determined from reciprocal space maps around the 113 reflection. The mass density was obtained from X-ray reflectivity measurements, as a necessary input to derive the shear elastic constant (C44) from BLS spectra. The evolution of the C44 constant with temperature was investigated using an original high-temperature chamber combined to the optical BLS set-up.
Authors : P. Písařík 1,2,*, M. Jelínek 1,2, J. Remsa 1,2, J. Zemek 2, K. Jurek 2, J. Luke 3 and J. epitka 3
Affiliations : 1 Czech Technical University in Prague, Faculty of Biomedical Engineering, nam. Sitna 3105, 272 01 Kladno, Czech Republic 2 Institute of Physics ASCR v.v.i., Na Slovance 2, 182 21 Prague 8, Czech Republic 3 Czech Technical University in Prague, Faculty of Mechanical Engineering, Technicka 4, 166 07 Prague, Czech Republic
Resume : Silver doped diamond-like carbon (Ag-DLC) were deposited on silicon (Si 100), fused silica (FS) and titanium substrates (Ti-6Al-4V) by dual pulsed laser ablation (dual-PLD) using two KrF excimer lasers and two targets (graphite and silver). The composition was analyzed using wavelength-dependent X-ray spectroscopy a XPS. The Ag content increased from 1.0 at. % to 10.6 at. %. The topology and surface properties as roughness of layers were studied using scanning electron microscopy and atomic force microscopy. With the silver concentration increased the roughness and the number of droplets. The mechanical properties of Ag-DLC films have been investigated. Hardness (reduced Young's modulus) was determined by nanoindentation. Hardness of our layers grown as a silver content decreased, as well as reduced Young's modulus. Films adhesion was studied using scratch test and with concentration of silver decreasing. This result opens further possibility for application of Ag-DLC films in medicine.
Authors : A.D. Pogrebnjak, I.V. Yakushchenko, O.V. Bondar, V.M. Beresnev, K. Oyoshi, H. Amekura, Y. Takeda, B.O. Postolnui
Affiliations : Sumy State University (Sumy, Ukraine); Karazin National University (Kharkiv, Ukraine); National Institute for Material Science (Tsukuba, Japan), IFIMUP and IN-Institute of Nanoscience and Nanotechnology University of Porto (Porto, Portugal)
Resume : Fabrication of nitrides or carbides of high-entropy alloys is an actual task of modern materials science. Good wear and corrosion resistance, resistance to oxidation, high hardness and good plasticity characterize such materials. Clarification of the limits of resistance of such coatings to ion implantation is also a very important task nowadays. Nanostructured multicomponent (TiZrHfVNbTa)N coatings were deposited on steel disks using Arc-PVD method in the nitrogen atmosphere under different deposition conditions. We provided pulsed deposition regime by applying of the high-voltage pulse generator in order to increase the energy of ion-plasma flux during deposition process. It improved the adhesion of the coatings to substrates and fabricated coatings with more disperse structure. Thickness of the fabricated coatings was 8 µm. We found forming of the phase with fcc lattice of the NaCl structure type in the deposited coatings. We used negative Au- ions for ion implantation, the doze was 1×10^17 cm^(-2), kinetic energy was 60 keV. Ion implantation led to forming of the disordered polycrystalline structure without preferred orientation of the fcc-phase, decreasing of the size of nanocrystallites from 8 nm to 1÷3 nm, increasing of the nanohardness up to 33 GPa in the implanted layer and increasing of the hardness of the coatings up to 51 GPa. Resistance of the fabricated coatings to irradiation by Au- ions was rather good.
Authors : V.V. Uglov, N.T. Kvasov, N.N. Dorozhkin, I.V. Safronov, V.I. Shymanski
Affiliations : Belarusian State University, Minsk, 220030, Nezavisimosty ave., 4, Belarus
Resume : In the present work we investigated the dependence of mechanical properties of nc-TiN/a-SiNx composites on the microstructure by means of multi-scale modeling. Components of tensor of elastic moduli Cij for crystalline nanocluster TiN and amorphous matrix a-SiNx were calculated by the method of molecular dynamics. Afterwards, Young's modulus E, shear modulus G, bulk modulus B and Poisson's ratio ν were obtained. The theory of composites elasticity based on the Eshelbys principle and polydisperse model was used to determine the effective elastic moduli (Eeff, Geff, Beff) for the nanocomposites. The amorphous matrix a-SiNx was represented as amorphous state Si3N4 formed by quenching from the melt, the local structure analyzed by pair radial distribution function. The nc-TiN particles were described by non-periodic boundary conditions providing the surface tension effect. The simulation showed that the elastic moduli of the nc-TiN particles with the size of about 10 nm are close to the values of corresponding bulk single crystals. When reducing the size up to 2 nm, there is an increase in the modules G at 13 %, the modulus B at 7% and modulus E at 12 %. The effective moduli of the composites increase with the volume fraction of the nc-TiN particles. The results showed that the values of the effective moduli Geff, Beff and Eeff are equal to 190 GPa, 330 GPa and 478 GPa, respectively, for the composite with 0.9 volume fraction of nc-TiN particles of an average size about 4 nm.
Authors : V.V. Uglov1,2, G. Abadias3, S.V. Zlotski1, I.A. Saladukhin1, V.I. Shymanski1, A. Michel3
Affiliations : 1Belarusian State University, Minsk, 220030, Nezavisimosty ave., 4, Belarus; 2Tomsk Polytechnic University, Tomsk, 634028, Lenina ave., 2a, Russia; 3Institut Pprime, Université de Poitiers-CNRS-ENSMA, Dpt. Physique et Mécanique des Matériaux, SP2MI, Téléport 2, F86962 Chasseneuil-Futuroscope cedex, France
Resume : The addition of metalloid atoms into binary nitrides of transition metals can significantly improve their mechanical properties as well as the oxidation resistance and thermal stability that is determined by the structure and phase state. In the present work the structural and phase transformations in ZrSiN system depending on Si content were investigated. The ZrSiN films have been deposited onto Si (001) wafers by a reactive unbalanced magnetron sputtering method at the temperature of 600°C. Zr and Si targets were co-sputtered under mixed Ar+N2 plasma discharges. Varying the power of the Si target from 40 to 200 W, the power of the Zr target being fixed at 300 W, resulted in silicon concentration to increase from 3.2 to 22.1 at.% in the films. According to TEM observations the synthesized films are biphase nanocomposite systems consisting of ZrN nanocrystals surrounded by X-ray amorphous SiNy matrix. Pure ZrN films are characterized by (111) preferred orientation that changes to (200) with Si addition. Transformation of nanocomposite structure of the films into X-ray amorphous state is observed for the film with 22.1 at.% of Si. Thermal annealing of the ZrSiN system (22.1 at. % Si) in vacuum at the temperature of 1000°C resulted in ZrN crystallization from X-ray amorphous matrix of ZrSiN. The hardness, elastic constants and tribological properties of the ZrSiN films were also determined as a function of Si content.
Authors : Michael Tkadletz1, Nina Schalk2, Manfred Wiesner1, Markus Pohler3, Christoph Czettl3, Kilian Bartholomé4, Markus Winkler4, Christian Mitterer2
Affiliations : 1Materials Center Leoben Forschung GmbH, Roseggerstrasse 12, 8700 Leoben, Austria; 2Department of Physical Metallurgy and Materials Testing, Montanuniversitat Leoben, Franz Josef-Strasse 18, 8700 Leoben, Austria; 3CERATIZIT Austria GmbH, Metallwerk-Plansee-Strasse 71, 6600 Reutte, Austria; 4Fraunhofer Institute for Physical Measurement Techniques IPM, Energy Systems (ES), Heidenhofstrasse 8, 79110 Freiburg, Germany
Resume : During severe machining applications, the cutting edges of the tool are exposed to high temperatures. Typically, PVD or CVD hard coatings are applied to minimize wear and to increase the lifetime of these tools. The evaluation of the suitability of such coatings is mainly based on reviewing their hardness, friction and wear as well as their oxidation resistance. However, thermo-physical properties like thermal expansion, thermal conductivity and heat capacity are crucial material properties to understand the in-service behaviour of cutting tools. Values of those properties are rarely found in literature for hard coatings. Furthermore, deposition parameters, chemical composition and coating architecture are assumed to have a major influence on these thermo-physical properties. Therefore, the rarely found literature values should be used carefully and the determination of actual values for individual coatings is advisable. Within this work, different techniques to investigate the thermo-physical properties of state-of-the-art PVD TiAlN and CVD Al2O3 and TiCN coatings are presented. High temperature X-ray diffraction and wafer curvature methods were applied to determine the thermal expansion of the coatings up to temperatures of 1000 ?C. Time-domain thermo-reflectance and the 3-method were used to determine the thermal conductivity of the samples at room temperature. Moreover, the complementary use of both techniques facilitated the determination of the heat capacity of the samples at room temperature. Additionally, the heat capacities were determined for temperatures up to 700 ?C using differential scanning calorimetry. The combination of the presented techniques for determination of the thermo-physical properties with well-established mechanical and tribological characterization methods will contribute to the development of further advanced design approaches for hard coatings for cutting tools.
Authors : Lenka Strbkova (1), Anton Manakhov (2), Adrian Stoica (2), Lenka Zajickova (2,3), Radim Chmelik (1)
Affiliations : 1 - Experimental Biophotonics Research Group, Central European Institute of Technology, Brno University of Technology, Technicka 3058/10, 616 00 Brno, Czech Republic.; 2- Plasma Technologies, CEITEC - Central European Institute of Technology, Masaryk University Kotlarska, 2, Brno 61137, Czech Republic; 3-Department of Physical Electronics, Faculty of Science, Masaryk University, Kotlarska, 2, Brno 61137, Czech Republic
Resume : The understanding of the surface-cell interaction plays important role for the biomaterials development and bioengineering. The surfaces exhibiting high biocompatibility (cell adhesion) are employed for tissue engineering, while the cell repellent surfaces are used for anti-fouling coating. It is well known that amine groups increase the cell adhesion and proliferation. However, the influence of the amine layers properties, such as concentration of primary and secondary amines, water contact angle, surface roughness and thickness loss on cell adhesion must be further investigated. The stable amine-rich coatings were prepared by low pressure plasma polymerization of cyclopropylamine using radio frequency capacitively coupled discharge. The normal human dermal fibroblasts were plated on glass coverslips and imaged by the coherence-controlled holographic microscopy. Holographic microscopy enables to acquire quantitative phase images, from which valuable cell parameters can be obtained. Based on those parameters, the cell adhesion and proliferation were studied. According to the results, amine-rich films enhanced the conditions for the cell cultivation.
Authors : Marcela Elisabeta Barbinta-Patrascu(a), Stefan Marian Iordache(b), Ana Maria Iordache(b), Nicoleta Badea(c), Florina Lucica Zorila(d), Ioan Stamatin(b)
Affiliations : (a)University of Bucharest, Faculty of Physics, Department of Electricity, Solid-State Physics and Biophysics, 405 Atomistilor Street, PO Box MG-11, Bucharest-Magurele, 077125, Romania (b)University of Bucharest, 3Nano-SAE Research Center, PO Box MG-38, Bucharest-Magurele, Romania (c)University Politehnica of Bucharest, Faculty of Applied Chemistry and Materials Science 1-7, Polizu Str., 011061, Bucharest, Romania (d)Horia Hulubei National Institute of Physics and Nuclear Engineering - IFIN HH, IRASM Multipurpose Irradiation Facility, Magurele, Ilfov, Romania
Resume : This paper reports for the first time, a creative bottom-up design of novel hybrid structures based on bio-inspired lipid membranes, green nanosilver and chitosan. Silver nanoparticles were phytosynthesized using different aqueous plant extracts. In order to get a deeper insight into the nanocomposite formation, the biomimetic membranes were labelled with chlorophyll a (Chla); this photopigment sensed the changes occurred in artificial lipid bilayers at molecular level. The resulted biocomposites were characterized by different spectral methods: UV-VIS absorption and emission spectroscopy, Dynamic Light Scattering. The physical stability of the samples was evaluated by zeta potential measurements and their antioxidant potential by chemiluminescence method. Different surfaces coated with thin films of these biocomposites were characterized by AFM. The obtained biohybrids exhibited biocidal properties against Staphylococcus aureus, Escherichia coli and Enterococcus faecalis. These antioxidant and antimicrobial bio-based hybrids could be used as protective biocompatible coatings for bio-applications.
Authors : Ming Wang, Dong Wang, Shaobin Yang, Peter Schaaf
Affiliations : Liaoning Technical University; Ilmenau University of Technology; Liaoning Technical University; Ilmenau University of Technology;
Resume : The fracture behaviour of multilayers in the nanometer thickness range has attracted an increased attention due to microelectronics and high-speed technologies. In this work, Al/Si3N4 multilayers fabricated by magnetron sputtering on the silicon substrate were subjected to three points bend testing. It was investigated that the fracture behaviour of Al/Si multilayers with different individual layer thickness t (50, 100, 250 nm) but with the same total thickness (1 µm). There appeared plastic shear fracture (pile-ups at interface) at submicron meter scale, while there appeared quasi-brittle shear fracture (cracks along grain boundary) at nanometer scale. When the individual layer thickness decreased from submicron meter scale to nanometer scale, it performed significant size effect of the Al/Si3N4 multilayer fracture strain at the topmost layer, which the thicker the individual thickness is, the higher the fracture strain is.
Authors : ILHEM. R. KRIBA1*; K. BENOUMSAAD1; A. DJEBAILI2
Affiliations : 1 Plasma Laboratory - Faculty of Sciences Department of Physics- University of Batna- Algeria 2 Laboratory of chemistry and environmental chemistry L.C.C.E - University of Batna- Algeria,
Resume : The plasma spray coating technology is widely used in many sectors of industry to protect surfaces against thermal heat, wear, or corrosion. In plasma spray coating process, particles are fed into a high- velocity, high- temperature gas jet where they melt or partially melt while being propelled at high velocity onto the surface to be coated. Particles land on the solid surface where they spread, solidify and agglomerate to form a thin layer. The flattening characteristics of the droplets impinging on a substrate are important determinants in governing the eventual quality of the plasma spray coating. Because the mechanical performance of the coatings depends crucially on the particles flattening and intersplat bonding, such studies are very important to unravel the complex interaction between spray parameters and coating properties. Different codes have been developed in recent years to simulate the overall thermal spraying process, as well as the growth of the 3D coatings. The present investigation was carried out to have an approach to systematize the atmospheric plasma spraying process of two molten droplets in order to create a basis for numerically modelling the plasma dynamics, the coating formation mechanisms and to predict the particle thermo- kinetic state at impact. Key words: plasma spray, plasma dynamics, coating formation, thermo-kinetics
Authors : K. BENOUMSAAD1; ILHEM. R. KRIBA1*; A. DJEBAILI2
Affiliations : 1 Plasma Laboratory - Faculty of Sciences Department of Physics- University of Batna- Algeria 2 Laboratory of chemistry and environmental chemistry L.C.C.E - University of Batna- Algeria,
Resume : Plasma spray deposition is one of the most important technologies available for producing the high-performance surfaces required by modern industry. In this process, powder of the coating material is fed into high-temperature plasma, which melts and accelerates the powder; the molten particles subsequently hit and solidify on the surface to be coated. Most of the applications require coatings with a high density, which are well bonded to the substrate. To obtain good quality coating, the powder particle must be at least partially molten and hit the substrate with a high velocity. The flattening characteristics of the droplets impinging on a substrate are important determinants in governing the eventual quality of the plasma spray coating. Because the mechanical performance of the coatings depends crucially on the particles flattening and intersplat bonding, such studies are very important to unravel the complex interaction between spray parameters and coating properties different codes have been developed in recent years to simulate the overall thermal spraying process, as well as the growth of the 3D coatings, in which entrained particles are modeled by stochastic particle models, fully coupled to the plasma flow. Similarly to previous work, there are still a lot of assumptions involved in these codes, dealing with the shape of the droplets, the degree of splattering edge curl up, the porosity of the coating, and so on. The present investigation was carried out to have an approach to systematize the atmospheric plasma spraying process in order to create a basis for numerically modeling the plasma dynamics, the coating formation mechanisms and to predict the particle thermo- kinetic state at impact. Key words: plasma spray process, flattening, coating, solidification, numerical model
Authors : V.V. Uglov1,2, N.T. Kvasov1, V.M. Astashynski3, R.S. Kudaktsin3, A.M. Kuzmitski3
Affiliations : 1Belarusian State University, Minsk, 220030, Nezavisimosty ave., 4, Belarus; 2Tomsk Polytechnic University, Tomsk, 634028, Lenina ave., 2a, Russia; 3A.V. Luikov Heat and Mass Transfer Institute of the National Academy of Sciences of Belarus, Minsk, 220072, P. Brovka Str., 15, Belarus
Resume : Composite layers with refractory metal silicides are of great interest for hardness increase. Magnetron sputtering and compression plasma flow treatment were used to synthesize modified layer containing titanium and tungsten silicides in carbon steel. Synthesis was carried out in two stages. First titanium (0.5 μm), silicon (1 μm) and tungsten (0.5μm) coatings were deposited on carbon steel by means of magnetron sputtering. Then this system was treated by compression plasma flow. XRD investigations showed that after treatment with plasma flow energy density 5-7 J/cm2 the resulting modified layer contained silicides WSi2 and TiSi. If energy density was more than 7 J/cm2 only WSi2 formed. Structure of modified layer was investigated by means of SEM. It was established that its thickness was from 1 to 5 μm. EDX and XRD analysis showed that with increasing plasma flow energy density distribution of elements in modified layer sought to uniform and silicide amount decreased. It can be concluded that compression plasma flow allows to synthesize modified layer in carbon steel containing silicides WSi2 and TiSi with simultaneous steel alloying with coating elements.
Authors : . Mekinis, A. Vasiliauskas, K. lapikas, A. Čiegis, T. Tamulevičius, S. Tamulevičius
Affiliations : Kaunas University of Technology, Institute of Materials Science, Barausko 59, Kaunas, Lithuania
Resume : Titanium nitride (TiN) films are widely used as protective coatings and diffusion barrier interlayers due to their high hardness, wear and corosion resistance. At present TiN is considered as a prospective optical material due to the recently found surface plasmon resonance effect in it. As plasmonic material TiN has some advantages over Au, Ag, Cu: lower losses in the visible light range, compatibility with semiconductor device technology, high temperature stability. In the present study TiN films were deposited by reactive high power pulsed magnetron sputtering (HIPIMS) of Ti target. Some samples were grown by DC magnetron sputtering. Technological advantage of HIPIMS over conventional DC magnetron sputtering is possibility to acieve achieve high plasma densities comparable with the case of the cathodic arc deposition or pulsed laser ablation. Structure and composition of the TiN films were studied by x-ray diffractometry, scanning electron microscope equipped with energy-dispersive X-ray spectroscope and X-ray photoelectron spectroscopy. Surface morphology was investigated by atomic force microscopy. Reflectance and absorption spectra of the deposited films were investigated in ultraviolet, visible light and near infrared ranges. Influence of the deposition conditions on optical properties of TiN films was investigated. Possible relations between the optical properties and structure as well as chemical composition of TiN films were considered.
Authors : D.Chaliampalias1, L.Kolaklieva2, R. Kakanakov2, N.Vouroutzis1, N.Pliatsikas1, D.Stathokostopoulos1, E.Pavlidou1, P.Patsalas1, Ε.K.Polychroniadis1, Κ.Chrissafis1, G.Vourlias1
Affiliations : 1Department of Physics, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece; 2Central Lab. of Applied Physics, Bulgarian Academy of Sciences,59 St. Petersburg Blvd., 4000 Plovdiv, Bulgaria
Resume : Cathodic arc deposition is a promising coating method for the deposition of transition metal nitrides because it is possible to produce tailored structures by modifying the current of the targets and the nitrogen pressure. The as produced materials fulfill most of the requirements for drilling and cutting applications. CrAlSiN quaternary films are reported to have the best mechanical and oxidation performance as they incorporate the beneficial effects of CrN while the presence of Al forms compounds which offer significant promotion to the film properties. Si amounts form amorphous Si-N which impedes the propagation of cracks. Moreover, the deposition of such film following a gradient technique improves the adhesion with the substrate. The aim of this work is the investigation of the structure and mechanical properties of gradient CrAlSiN films deposited with CAD method. Furthermore, the high temperature oxidation of the coupons was also investigated and compared with that of widely applied mechanical materials. The examination of the deposited films was performed by electron microscopy, X-ray diffraction and photoelectron spectroscopy while the oxidation tests were performed by thermogravimetric measurements. The examination of the as deposited films showed that they had nanostructured morphology while grains grow creating distinguishable columnar formations. Moreover the measured mechanical properties were comparable with the industrially applied materials. Finally the CrAlSiN films were found to have no mass gain, due to oxidation, up to 1000oC but Fe and Cr diffusion from the substrate was detected from 900oC. This work was supported from IKY Fellowships of excellence for postgraduate studies in Greece Siemens Program.
Authors : A. C. Popescu1, D. Cristea2, M. Stoicanescu2, A. Crisan2, G. Guilloneau3, E. Lambers4, G. Socol1, V. Craciun1
Affiliations : 1National Institute for Lasers, Plasma and Radiation Physics, Magurele, Romania 2Materials Science Department, Transilvania University, Brasov, Romania. 3EMPA, Thun, Switzerland 4Major Analytical Investigation Center, University of Florida, Gainesville, USA
Resume : Thin TiC films (400-500 nm thickness) were synthesized on Si substrates heated to 500°Cby the pulsed laser deposition technique using a KrF excimer laser source. The deposition were performed in an UHV stainless steel installation under a methane or nitrogen atmosphere at pressuresfrom 10-4to 10-5mbar. The films surface morphology was investigated by scanning electron microscopy. Films thickness, profiles and surface features were extracted from con-focal microscopy image processing. All films had very smooth surfaces and were very dense, as also indicated by the simulations results of X-ray reflectivity curves.The films structure was investigated by grazing incidence and symmetrical X-ray diffraction.The use of a high laser fluence (~6 J/cm2)during deposition resulted inthe synthesis of dense films with small crystallite sizes, and a high compressive stress level, which influenced the mechanical proper-ties of the films. Hardness and elasticityof the films have been studied by nanoindentation. The variable para-meter was set to be the indentation depth, at no more than 25% of the film thickness. Lower indentation depths resulted in inconclusive results. The hardest coatings were obtained in ni-trogen atmosphere (Hit~35 GPa). Samples synthesized in methane ambient had hardness val-ues of ~ 30 GPa. The samples were quite rigid, with Youngs modulus of ~300 GPa for films deposited in nitrogen and ~250 GPa for samples produced in methane atmosphere.
Authors : C. Popescu1, L. Duta1, G. Socol1, G. E. Stan2, M. Husanu2, S. Iordache3, I. Stamatin3, C. Himcinschi4, V. Craciun1, A. C. Popescu1
Affiliations : 1National Institute for Lasers, Plasma and Radiation Physics, Magurele, Romania 2 National Institute of Materials Physics, Magurele, Romania 3 3Nano-SAE Research Center, University of Bucharest, Romania 4 Institute of Theoretical Physics, TU Bergakademie Freiberg, Freiberg, Germany
Resume : Commercially available cutting saws and drills covered by DLC protective films were tested against similar tools protected by PLD laboratory-synthesized coatings. To increase the films adherence to metallic tools, a buffer layer with gradual composition was synthesized by magnetron sputtering, prior deposition. Films were deposited in methane, nitrogen or vacuum. Co-doped DLC was symthesized by combinatorial pulsed laser deposition, by simultaneous irradiation of Co and graphite targets. Films content and structure was assessed by XPS, Raman and X-ray diffraction. In case of Co-doped films, supplementary EDX analyses were conducted to determine the content and distribution of Co in films. Morphology and surface features were studied by AFM. Films adherence to the metallic substrate, with or without buffer layer, was determined by pull-out tests. The mechanical properties were assessed by nanoindentation and wear tests. Special emphasis was put on the influence of Co content in the films and deposition ambient composition upon the mechanical properties of the layers. The deposition conditions for films with the best mechanical properties were selected and new layers were deposited on drills and saws and tested mechanically in real applications vs commercially available tools. Microscopic and profilometric studies showed that the wear rate and delamination were significantly reduced for films synthesized by PLD compared to commercially available products.
Authors : I. Pana, C. Vitelaru, N.-C. Zoita, M.Braic
Affiliations : National Institute for Optoelectronics, 409 Atomistilor St., Magurele-Bucharest, Romania
Resume : The optical emission spectroscopy technique was used to enable insights into the RF sputtering process of Si target in an argon/nitrogen reactive gas environment. The nitrogen mass flow ratio was the main control parameter. No hysteresis behavior of the sputtering process were observed on a large interval of FR (0 to 90%), indicating the possibility to obtain progressive and reversible changes of plasma chemistry and thus of films properties. The evolution of plasma emission lines intensity vs nitrogen flow reveals process intervals relevant for both plasma chemistry and thin films deposition. Therefore, thin films of silicon nitride (SiNx) with tunable optical properties were deposited and characterized, in order to correlate the deposited films properties with the ones of reactive plasma. It is shown that the evolution of the deposition rate is similar with that of the Si emission line intensity, while the refractive index, the absorption coefficient and the width of the optical band gap, Eg, are well correlated with the process intervals identified from the evolution of nitrogen emission lines intensities. The largest variations of the optical properties were obtained for reactive gas ratios< 15 %. The refractive index varies from ~ 2.75 to ~ 1.7 and the optical band gap width changes from 1.86 eV to 4.56 eV when FR varies from 5% to 15 %. The maximum Eg value, 4.68 eV, is obtained for FR = 20 %.
Authors : M. Braic1, N.C. Zoita1, M. Danila2, C. E. A. Grigorescu1, C. Logofatu3
Affiliations : 1 National Institute for Optoelectronics, 409 Atomistilor St., Magurele-Bucharest, Romania 2 National Institute for Microtechnologies, Bucharest, Romania 3 National Institute for Materials Physics, Magurele-Bucharest, Romania
Resume : Hetero-epitaxial TiC thin films were deposited at 100 0C on MgO (001) by DC reactive magnetron sputtering in a mixture of Ar and CH4. The 62 nm thick films were analysed for elemental composition and chemical bonding by Auger electron spectroscopy, X-ray photoelectron spectroscopy and micro-Raman spectroscopy. The crystallographic structure investigation by high resolution X-ray diffraction revealed that the film consist of two layers: an interface partially strained epilayer with high crystalline quality, and a relaxed layer, formed by columnar grains, maintaining the epitaxial relationship with the substrate. The films presented smooth surfaces (RMS roughness ~ 0.55 nm), with circular equi-sized grains/crystallites with comparable mean lateral sizes, as observed by atomic force microscopy. The Hall measurements in Van der Pauw geometry revealed relatively high resistivity value of about 620 µΩ cm, ascribed to electron scattering on interfaces, on grain boundaries and on different defects/dislocations.
Authors : M. Apreutesei1, P. Djemia2, L. Belliard3, G. Abadias4, A. Billard5, C. Esnouf1, L. Joly Pottuz1, P. Steyer1
Affiliations : 1: MATEIS Laboratory, INSA de Lyon, 20 av. A. Einstein, 69621Villeurbanne, France; 2: LSPM-CNRS, Université Paris 13, Sorbonne Paris-Cité, 99 Avenue J.B. Clément 93430 Villetaneuse, France; 3: UPMC-Institut des NanoSciences de Paris, 4 place Jussieu 75252 Paris cedex 055; 4: Département Physique et Mécanique des Matériaux, Institut P, CNRS-Université de Poitiers-ENSMA, SP2MI - Téléport 2, BP 30179, F86962 Futuroscope-Chasseneuil, France; 5IERTES-LERMPS Laboratory, Site de Montbéliard, 90010 Belfort Cédex, France
Resume : Metallic glasses (MGs) are innovative materials with prone applications in various domains due to crystal-free structure and inherent toughness. We investigated the structure and mechanical properties of Zr1-xCux metallic glass films deposited by dc magnetron co-sputtering from pure Zr and Cu targets in Ar plasma discharge on different substrates. Process parameters target current intensity especially was varied and the conditions for glass forming ability identified. Their influence on the thickness, the films microstructure, the chemical composition and the mechanical properties were explored. The structural properties of the metallic glass compounds were characterized by X-ray diffraction and X-ray reflectivity. The thermal stability of the films was deduced from in situ X-ray diffraction analysis (from room temperature up to 600 °C) and correlated with the differential scanning calorimetry technique. When characterized at a deeper scale by TEM, some films were in fact composed of nanometer-size crystallized domains. The picosecond ultrasonics, the Brillouin light scattering and the nanoindentation techniques were employed to measure the longitudinal VL and the transversal VT sound velocities, the elastic properties (C11, C44 and E) and the nano-hardness H. Some relationships between elastic moduli (Youngs modulus E and shear modulus G = C44) structural state and thermal properties (glass temperature Tg) are identified. Keywords Thin film metallic glass, structural stability Brillouin light scattering, picosecond ultrasonics, nanoindentation
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Authors : A. Rizzo, D. Valerini, L. Capodieci,L. Mirenghi, F. Di Benedetto
Affiliations : ENEA UTTMATB Brindisi
Resume : Zirconium nitride (ZrN) coatings due to its inherent high hardness, wear resistance, corrosion resistance and gold like colour have attracted many applications ranging from coatings for wear resistance, corrosion resistance, coatings for biomedical appliances, high reflectivity optical and decorative surfaces. ZrN coating properties have shown a strong relationship with their employed techniques of growth process. Reactive Bipolar Pulsed Dual Magnetron Sputtering (BPDMS) is a powerful technique for the deposition at high deposition rate of dense and defect free coatings. Operating in the mid-frequency range the periodic target voltage reversals suppress arcing and stabilize the reactive sputtering process. Despite the success of the dual bipolar process, there are many aspect of this complex process that are not yet well understood, particularly the interrelationships between target voltage waveforms and plasma parameters and their impact on film growth. We studied the effect of BPDMS from a Zr target on structural and mechanical properties of the deposited ZrN films. We found that the hardness increases with decreasing of grain size and increasing packing factor. For BPDMS with 80 kHz and increasing duty cycle duration from 20 to 80 % the structure changes from a (111)-preferential oriented to random oriented single-phase cubic, resulting in hardness increases from 20 to 32 GPa, respectively.
Authors : Abdel-Aziz El Mel, Farah Boukli-Hacene, Leopoldo Molina-Luna,§ Nicolas Bouts, Benoit Angleraud, Adrien Chauvin, Damien Thiry, Eric Gautron, Nicolas Gautier, and Pierre-Yves Tessier
Affiliations : Institut des Matériaux Jean Rouxel, IMN, Université de Nantes, CNRS, 2 rue de la Houssinière B.P. 32229, 44322 Nantes cedex 3, France §Technische Universität Darmstadt, Department of Material- and Geosciences, Alarich-Weiss-Strasse 2, 64287 Darmstadt, Germany
Resume : Nanoporous materials exhibiting a sponge-like structure have recently revealed enhanced properties compared to their solid counterparts. Dealloying, which is an ancient alchemy technique used in the past in depletion gilding for the surface enrichment of artifacts of gold alloys, is among the most popular methods employed to create nanoporous materials. Currently, the conversion chemistry of such process has attained enough maturity to start concentrating the efforts on the integration of this promising class of materials in practical applications. An elegant way to achieve this goal is by using thin films technology. In this work we shed the light on a novel approach to synthesize nanoporous thin films of various materials (e.g., carbon and gold) exhibiting a sponge-like structure. Such process consists in the growth of binary alloy  or nanocomposite  thin films by co-sputtering followed by a free-corrosion process in nitric acid. We explore the impact of the composition, the structure and the morphology of the as-grown thin film precursors on the dealloying process as well as on the final porosity and crystalline structure of the nanoporous films. Based on our experimental observations, a scenario is further proposed to provide a detailed explanation of the fundamental mechanisms occurring during the dealloying process of films with various structures.  El Mel et al, ACS Appl. Mater. Interfaces, DOI:10.1021/am5065816  Bouts et al, Carbon 83, 250, 2014
Authors : L. Major-1, J.M. Lackner-2, M. Kot-3, J. Morgiel-1
Affiliations : 1). Institute of Metallurgy and Materials Science; Polish Academy of Sciences, 25 Reymonta Street, 30-059 Cracow, Poland; 2). JOANNEUM RESEARCH- Materials- Institute for Surface Technologies and Photonics; Leobner Strasse 94; 8712 Niklasdorf, Austria; 3). University of Science and Technology, AGH, Aleja Adama Mickiewicza 30, 30-059 Cracow, Poland
Resume : Requirements for tribological protective coatings for medical tools, which would increase their wear and corrosion resistance, particularly are very high. The presented paper deals with the novel nanocomposite, multilayer protective coatings for tissue interaction elaboration and their diagnosis on metallic substrates. A hybrid PLD system was used for coatings deposition. In the presented work, nano- composite, Cr/CrN+[Cr/ a-C:H implanted by metallic nanocrystals] multilayer coatings have been developed for surface protection. The mechanical properties of the coatings were investigated by means of micro- hardness and elasticity modulus measurements. Bio- medical tests were done using eukaryotic cells. Microstructure analysis by TEM indicated that chromium which was implanted into a-C:H layers reacted with carbon forming chromium carbides. Carbides were distributed in the a-C:H structure as nano- multilayers.
Authors : Sami Rtimi, Cesar Pulgarin, Rosendo Sanjines, John Kiwi
Affiliations : Ecole Polytechnique Federale de Lausanne
Resume : This study presents the bacterial reduction by visible light absorbing nanocomposite stable, resistant and non-corrosive oxynitrides films presenting absorption in the visible spectral range and their silver derivatives. The design, sputtering, bacterial evaluation and surface characterization of uniform and adhesive nanoparticulate oxynitrides films is described in detail. The bacterial reduction was observed by these Ag- oxynitrides in the dark and with high kinetics under daylight/actinic light irradiation. The special interest for the oxynitrides is their low cytotoxicity and chemical stability, making them suitable as supports for highly oxidative Ag-nanoparticles. The Ag-TiON fast inactivation kinetics concomitant with low cytotoxicity, low cost and long operational lifetime are the essential requirements for the potential practical application of these antibacterial surfaces. The aim here is to show the bacterial inactivation as a function oxynitride composition and details of the microstructure and properties by up-to-date surface characterization techniques.
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Authors : G. Abadias1, I.A. Saladukhin2, V.V. Uglov2,3, S.V. Zlotski2, A. Michel1, S.N. Dub4, Ph. Djemia5, A.Yu. Rovbut2
Affiliations : 1Institut Pprime, Université de Poitiers-CNRS-ENSMA, Dpt. Physique et Mécanique des Matériaux, SP2MI, Téléport 2, F86962 Chasseneuil-Futuroscope cedex, France; 2Belarusian State University, Minsk, 220030, Nezavisimosty ave., 4, Belarus; 3Tomsk Polytechnic University, Tomsk, 634028, Lenina ave., 2a, Russia; 4Institute of Superhard Materials, NAS of Ukraine, Kiev, 04074, 2, Avtozavodskaya Str.,Ukraine; 5Laboratoire des Sciences des Procédés et des Matériaux (LSPM) - UPR 3407 CNRS, Université Paris 13, Sorbonne Paris Cité, 99 Avenue J.B.Clément 93430 Villetaneuse, France
Resume : Quaternary TiZrAlN and TiZrSiN films were grown at Ts=600 °C by reactive magnetron sputtering in Ar+ N2 plasma discharge from elemental targets. Deposition occurred at the constant power of Ti and Zr targets, while changing the Al (resp. Si) power and adjusting the N2 flow rate, resulting in stoichiometric nitride films (N concentration between 48 and 53 at.%) with Al (resp. Si) content up to 23 at.% (resp. 13 at.%) and fixed Zr :Ti ratio of 1.1. It is shown that single-phase, cubic (Ti,Zr)1-xAlxN solid solutions are stabilized upon incorporation of Al, while dual-phase, nanocomposite TiZrSiN films consisting of cubic TiZrN grains surrounded by SiNy phase are formed upon incorporation of Si. The lattice parameter of Al-containing films linearly decreases with the increase in Al concentration. During vacuum annealing (up to 1000 °C), the subsequent increase in the lattice parameter can be connected with out-diffusion of Al from c-TiZrAlN phase. The lattice parameter of Si-containing films is close to that of pure TiZrN film. The phase composition of TiZrSiN films is stable under vacuum annealing, except above 1000°C where a weak ZrN (200) reflection appears, indicating that structural phase transformation occurred. Both TiZrAlN and TiZrSiN films are under compressive stress state (up to -2 GPa). For these films the maximum hardness, 25 GPa (resp. 29 GPa) is achieved at Al content of 19 at.% (resp. Si content of 6 at.%).
Authors : E. Calvie, M. Apreutesei, A. Malchere, T. Douillard, J. Rethore, Ph. Goudeau, E. Damond, C. Esnouf, P. Steyer
Affiliations : INSA de Lyon, MATEIS Laboratory; INSA de Lyon, LaMCoS Laboratory; Université de Poitiers, P' Laboratory, IonBond Company
Resume : Keywords : hard thin films, oxidation, microstructure, SEM, TEM, in situ approach, micro-tensile tests, Digital image correlation New economical and ecological tendencies in the industrial area yield to increase machining speeds together with a drastic restriction of lubricant-cooling fluids. As a consequence, the surface of coated tools has to withstand extreme conditions, especially in terms of temperature, which can locally reach 1000°C, and severe deformation. Simple transition metals nitrides cannot sustain such extreme conditions. Therefore, a new generation of coating enriched in aluminium, as it is the case for AlTiN and AlCrN, and reactive elements, such as yttrium to form CrAlYN or AlTiYN, has been developed. The aim of this talk is to characterize at a fine scale and in situ the damage linked to an important controlled deformation of the surface, and to determine its consequences regarding the oxidation behavior. Influence of the microstructure and of yttrium incorporation is studied through a metallurgical and micro-mechanical approach. 3 µm-thick films were synthesized by arc-evaporation of Al60Cr40 and Al59.1Cr30.4Y1.5 targets into a PVD random arc reactor, using a constant evaporation intensity of 80 A. Deposition was conducted for a bias voltage applied in the range of -30/-60 V at a deposition pressure of 3 Pa. Surface defects are observed using SEM, TEM and quantitatively determined by electrochemistry. Residual stresses of films are measured through XRD measurements using the sin2 psi method. Of prime interest is the cracking behavior, investigated at a deep-scale through a micro-tensile test machine able to be implemented into the SEM chamber. The dynamic of the surface is got through a specific DIC (Digital Image Correlation) post-treatment. Deformation behaviors are then discussed in light of chemistry, residual stresses and microstructure of films.
Authors : Spyros Kassavetis, Alexis Spiliotis, Stelios Karamanidis and Stergios Logothetidis
Affiliations : Lab of Thin Films - Nanosystems & Nanometrology (LTFN), Physics Department, Aristotle University of Thessaloniki, Thessaloniki, Kentriki Makedonia, GR-54124, Greece
Resume : Accurate characterization of the mechanical properties of superhard, nanocomposite thin films is particularly complicated, but it is crucial since these nanomaterials attract the interest of the scientific community and meet the needs of the protective coatings industry. In this paper, we focus on the accurate nanomechanical characterization of superhard Ti-B-N nanocomposite thin films using depth-sensing nanoindentation and atomic force microscopy (AFM). Nanoindentation was performed using two Berkovich (triangular-pyramid) type diamond indenters with different tip roundness (nominal tip roundness 20 nm and 50 nm), while the AFM was used to image the nanoindentation imprints and to study the difference in the deformation induced to the superhard films by the two different Berkovich diamond tips. The sharper diamond tip was found to induce elastic/plastic deformation at swallower depth (~10 nm), fact that enables the measurement of the hardness (H) and the elastic modulus (E) closer to the thin film surface. In addition the analysis of the nanoindentation load-displacement curves showed that both the H and E values were found to be considerably higher in the case of the sharper tip (e.g. 52 GPa against 31 GPa for the H in the case of the most promising sample). Finally, the mechanical properties were correlated with the thin film structure coming from the X-rays characterization. Acknowledgments: Hellenic National Strategic Reference Framework 2007?2013, contract no. 11ΣΥΝ-5-1280, Project ?Nano-Hybrid?, within the Program ?Competitiveness and Entrepreneurship?.
Authors : F. Aousgi,1,* A. Harizi,2 M. Kanzari,2,3 R. chtourou1
Affiliations : 1 Laboratoire de Photovoltaïque (LPV), Centre de Recherches et des Technologies de l'Energie (CRTEn), Tech-nopole Borj Cédria B.P N°95 - 2050 Hammam-Lif Tunisie. 2 Laboratoire de Photovoltaïque et Matériaux Semi-conducteurs, ENIT-Université Tunis El Manar, BP 37, Le belvédère, 1002 Tunis, Tunisie. 3 Institut Préparatoire aux Etudes dIngénieurs de Tunis Montfleury -Université de Tunis.
Resume : In this work, the evolution of the structure and morphology of Sn4Sb6S13 thin films grown by thermal evaporation was investigated .The films were deposited onto glass substrates heated in the temperature range 30-200°C.The deposited films were characterized by X-ray diffraction (XRD), atomic force microscopy (AFM), Scanning electron microscopy (SEM), Homogeneous films were found to be preferentially orientated along the ((6 ) ̅11) direction. The surface morphological analysis revealed that the films had an average roughness increase from 0.58 to 6.45 nm with increasing the substrate temperature from 30 to 200 °C. The variations of the microstructural parameters, such as crystallite size (D), dislocation density (δ), stacking fault probability (α) and strain (ε) with substrate temperature were investigated. FTIR and Raman were used to obtain information about structural changes of Sn4Sb6S13 films.
Authors : Yong Jung Kwon, Han Gil Na, Hong Yeon Cho, Sung Yong Kang, Hyoun Woo Kim*
Affiliations : Department of Materials Science and Engineering, Hanyang University, 222 Wangsimni-ro, Seongdong-Gu, Seoul, 133-791, Korea
Resume : Owing to outstanding characteristics of carbon nanotubes (CNTs) such as small size, large surface area, hollow geometry, and highly sensitive electrical properties, CNTs have been widely used in a variety of devices and systems. We have prepared metal-CNTs core-shell nanostructures by sputtering technique with the metal target, subsequently investigating the effects of thermal annealing. The surface of metal-CNTs became rougher by the thermal annealing, being attributed to the agglomeration of the metal shell layers into the metal oxide (MOx) nanoparticles. The gas sensing test demonstrated that the MOx functionalization significantly improved the sensing performances, successfully attaining the higher sensitivity and faster response than bare CNTs. We have scrutinized the possible mechanisms for improvement of the sensing properties by MOx-functionalization.
Authors : F. Djeffal1,2, H. Bencherif1, K. Kacha1 and D. Arar1
Affiliations : 1) LEA, Department of Electronics, University of Batna, Batna 05000, Algeria. 2) LEPCM, University of Batna, Batna 05000, Algeria. E-mail: email@example.com, firstname.lastname@example.org Tel/Fax: 0021333805494
Resume : The optical confinement is an important parameter for enhancing the efficiency of solar cells. In this context, transparent conductive oxide coating (TCO) with randomly textured surfaces is widely used to improve optical confinement, where many numerical and experimental studies have been carried out to investigate the impact of the surface texture morphology on the electrical performance of the solar cell. However, till now, any analytical investigation is proposed to optimize and improve the electrical efficiency of SiGe-based solar cells, taking into account the texture morphology effects. In this paper we present an analytical investigation including texture morphology effects, in order to optimize the texture morphology and TCO design parameters. In the present paper, we propose an analytical model allowing the electrical efficiency optimization for Glass/ZnO:Al/SiGe/Si heterojunction solar cell, by taking into account the surface texture morphology, Al concentration and Ge mole fraction effects. A multi-objective genetic computation has been used to optimize triangular grating. Solar cell with optimized triangular grating exhibits an enhancement over planar and randomly triangular grating cells. The purpose of this work is to formulate novel design criteria based on analytical and optimization investigation of surface texture morphology that would help in obtaining a high electrical performance.
Authors : Arvaidas Galdikas, Teresa Moskaliovienė, Akvilė Petraitienė
Affiliations : Physics Department, Kaunas University of Technology, Studentų 50, LT-51368 Kaunas, Lithuania.
Resume : Cobalt-chromium (CoCr) alloys and austenitic stainless steels (ASSs) are the most suitable metallic biomaterials owing to their good wear and corrosion resistance, and sufficient biocompatibility. However, there are concerns over the wear of such biomaterials surfaces and toxic metal ions release when they are used as medical implants. Low temperature plasma assisted nitriding is an effective treatment that improves wear and corrosion resistance, and reduces the release of potentially harmful metal ions from these alloys. Expanded austenite phase, formed after plasma assisted nitriding of CoCr base alloys and ASSs, is characterized by the expansion of the alloy lattice and an anomalous diffusion of nitrogen. In this work the nitrogen diffusion in CoCr alloy and ASS is investigated on the basis of internal stress assisted diffusion model. Proposed model assumes that the stress field, associated with the distorted alloy lattice due to incorporation of nitrogen, effects the diffusive flux of nitrogen. It was shown, that the enhanced nitrogen diffusivity in the expanded austenite as well as a plateau-type shape of nitrogen depth profile can be explained by proposed model.
Authors : J. Schäfer (1), J.Hnilica (2), J. perka (2,3), A. Quade (1), V. Kudrle (2), R. Foest (1), L. Zajíčková (2,3)
Affiliations : (1) Leibniz Institute for Plasma Science and Technology e.V., 17489 Greifswald, Felix-Hausdorff-Straße 2, Germany; (2) Department of Physical Electronics, Masaryk University, Kotlářská 2, CZ-61137, Brno, Czech Republic; (3) CEITEC (Central European Institute of Technology), Masaryk University, Kamenice 753/5, CZ-62500, Brno, Czech Republic
Resume : TTMS has been used to study plasma enhanced chemical vapor deposition processes at atmospheric pressure (AP-PECVD). TTMS has been chosen because of its potential to form branched organosilicon polymers of regular structure that is used in the chemical synthesis. Despite the widespread surveying of various silicon-organic molecules for PECVD, the use of TTMS in AP-PECVD has not been investigated deeper yet. Deposited films based on TTMS exhibit diametrically opposed morphology from closely spaced smooth films to nano-dendriticaly branched 3D structures depending on the particular process. AP-PECVD processes have been performed with two different plasma jets. While they are alike regarding the geometry and injection of TTMS, they differ in electrical power and excitation frequency. The radiofrequency plasma (RF) jet  operates at lower power densities as compared to the microwave plasma (MW) jet . For all observed film morphologies, from amorphous, smooth films to films with dendritic structure, the results of the surface and film analysis (X-ray photoelectron spectroscopy and FTIR absorption) demonstrate their inorganic character. The carbon content does not exceed 5% while the IR absorption band of OH remains below the detection limit. The stoichiometry resembles that of silicon dioxide (Si:O=1:2). Supported by DFG TRR 24.  J. Schäfer et al., Plasma Phys. Control. Fusion 51, 12, 124045, 2009.  J. Hnilica et al., J. Phys. D: Appl. Phys. 45, 5, 055201, 2012.
Authors : Emile HAYE, Fabien CAPON, Silvère BARRAT, Pascal BOULET
Affiliations : Institut Jean Lamour UMR 7198, Parc de Saurupt, FRANCE
Resume : Perovskite materials with ABO3 formula present interesting properties depending on their composition, and are studied for their potential applications as smart or monitoring devices. Some of these perovskites based on iron and Rare Earth elements are particularly adapted as NOx gas sensors, or fuel cells electrodes, and the requirement of miniaturization and low power consumption in such electronic components has led to the development of thin films. The understanding of their growth and crystallization mechanisms are thus important to optimize their properties. In this work, we investigate crystallization mechanisms of REFeO3 (RE= La, Pr, Nd, Sm) thin films. Films were deposited by magnetron sputtering, from two metallic targets (RE and Fe), in reactive atmosphere (Argon + Oxygen), onto (100) undoped Si single-crystal. The deposition temperature was fixed at 400°C to avoid stresses and crystallization start. The chemical stoechiometry of these films was checked by energy X-ray analyses (EDS). As grown films were amorphous and crystallization was induced by heating it in a furnace. This crystallization develops during heating and this evolution was characterized by in situ XRD measurements. We have used Johnson-Mehl-Avrami-Kolmogorov (JMAK) model to quantify the kinetic crystallization of films. In a first step, XRD measurements were performed at different temperatures, to approximately determine the crystallization temperature. Secondly, XRD measurements were performed on a restricted diffraction angle range, to record area of (121) peak as a function of time. The peak area is linked to the crystallized fraction inside the film. Then, JMAK equations have been applied to find crystallization mechanisms, depending on Avrami parameters. Finally, Arrhenius law was used to calculate rate constant and activation energy of the crystallization reaction. We observe a constant increase of the energy required to crystallize the perovskite by decreasing the ionic radius of the Rare Earth element.
Authors : Anton Manakhov(1), Adam Obrusnik(1,2), Petr Jelinek(1,2), Miroslav Michlicek(1,2), David Necas(1,2), Marek Elias(1,2), Jan Cechal(3), Josef Polcak(3), Lenka Zajickova(1,2)
Affiliations : (1) Plasma Technologies, CEITEC Central European Institute of Technology, Masaryk University, Brno, Czech Republic; (2) Department of Physical Electronics, Faculty of Science, Masaryk University, Brno, Czech Republic; (3) Functional Properties of Nanostructures, CEITEC - Central European Institute of Technology, Brno University of Technology, Brno, Czech Republic
Resume : Carboxyl coatings are extensively used for adhesion promotion, bio-immobilization, surface reactions, thanks to their reactivity towards nucleophilic groups and high wettability. The deposition of relatively stable carboxyl-rich coatings using low-cost atmospheric pressure plasma processes was achieved by copolymerization of acrylic acid and ethylene or maleic anhydride and vinyltrimethoxysilane. The acrylic acid or maleic anhydride provide a reactive carboxyl group, while layer crosslinking is enhanced by adding a second monomer. The detailed research of the thickness loss and the retention of carboxyl function after immersion of such copolymers in water is not available in the literature. This work is aimed at the investigation of the plasma copolymerization of maleic anhydride and acetylene by atmospheric pressure dielectric barrier discharge. The quantification of the carboxyl groups was performed by X-ray photoelectron spectroscopy (XPS) C1s curve fitting and by derivatization with trifluoroethanol. The layer synthesized at optimized monomer flow rate and plasma power, contained 5 at% of COOH groups (determined by derivatization combined with XPS) and exhibited the thickness loss below 10% after 128 hours in water. The influence of plasma chemistry, gas dynamics and plasma power on the layer properties was studied. Numerical models were developed to understand the importance of the gas dynamics in the deposition process and optimize the set-up.
Authors : A. M. I. Trefilov*, P. Dinca**, O.G. Pompilian**, C. Luculescu**, A. Tiliakos*, E. C. Şerban*, A. Balan*, I. Stamatin*
Affiliations : * University of Bucharest, Physics Department, 3 Nano-SAE Research Centre, Bucharest-Magurele, Romania; ** National Institute for Laser, Plasma and Radiation Physics, RO-77125 Magurele, Romania
Resume : Raney type nickel alloys with high surface area and specific morphology are promising catalysts for low-temperature fuel cells, particularly alkaline and urea fuel cells. Our research focuses on improving the catalyst performance by controlling the shape and size of the nickel nanostructure. In this respect, we use thermionic vacuum arc deposition to produce Ni - Al thin films; the method employs two independent and constant electron beams emitted by externally heated cathodes inside a vacuum chamber. The resulting Ni - Al films are thermally treated at high temperatures, then activated with concentrated sodium hydroxide, which also results in aluminum leaching from the alloy. The aim of this work is to investigate skeletal nickel catalysts incorporation in alkaline fuel cells. The Raney type Ni nanostructures are evaluated by scanning electron microscopy and electrochemical methods; the prototype catalysts are then tested in an alkaline fuel cell.
Authors : Ali Tufani, Gozde Ozaydin Ince
Affiliations : Materials Science and Engineering Program, Faculty of Engineering and Natural Sciences, Sabanci University
Resume : In this study selective permeability of poly(hydroxyethylmethacrylate), p(HEMA), thin film membranes are investigated. P(HEMA) free standing thin films with different crosslink ratios are synthesized via initiated chemical vapor deposition (iCVD). Dependence of swelling kinetics on the chemical composition of the films is studied by spectroscopic ellipsometry and Fourier transform infrared spectroscopy. Selective permeation of dyes with different size and hydrophilicity through the membranes is investigated via diffusion tests using a side-bi-side cell and UV-vis spectroscopy. Using the diffusion studies of the model dyes, the relation between the chemical composition and the permeability coefficients of the membranes is studied and methods to tailor the selectivity of the membranes by tuning the fabrication methods are discussed.
Authors : M. Dinu, A.C. Parau, L. Constantin, I. Pana, M.Braic
Affiliations : National Institute for Optoelectronics, Magurele-Bucharest, Romania
Resume : Multicomponent carbide coatings, containing transitional metals, with or without Si, are promising ceramic materials, exhibiting high hardness, low residual stress, improved corrosion resistance. An amorphous coating - (CuTiYSiZr)C, and three crystalline coatings - (CuTiYCrNb)C, (TiYCrNbAl) and ZrSiC, were analyzed in term of elemental composition and crystallographic structure. The surface and in-depths coating morphology was correlated with their tribological performance, assessed in terms of friction coefficients and wear rates. Compared to the stoichiometric coatings with columnar structures, the overstoichiometric ones present finer, denser, and almost glassy structures. The existence of the free-carbon phase in overstoichiometric coatings, evidenced by Raman and XPS analyses, determined a reduced surface roughness, with a reduced coefficient of friction (<0.2) and low wear rates (of about 10-6 m3N-1m-1). The tribological characteristics similarities noticed for all the investigated overstoichiometric coating indicated that the amorphous carbon phase plays a major role, out-shadowing the nature of other elements, as well as their number. The increase of carbon content in the coating to about 80% determined an accentuated decrease of the surface roughness (RMS < 2 nm), resulting in a further decrease of the friction coefficient to about 0.05.
Authors : L. Constantin, C. Vitelaru, A.C. Parau, M. Braic
Affiliations : National Institute for Optoelectronics, 409 Atomistilor St, Magurele-Bucharest, Romania
Resume : Zr- and Cr- doped TiSiC coatings were deposited on Si and 316 L steel substrates by the cathodic arc technique using CH4 as reactive gas. Corrosion and wear tests in normal 0.9% NaCl solution were performed. Additional investigations on elemental composition, crystalline structure and surface morphology of the coatings were carried out. The following main conclusions are drawn from the experimental results of the present study. An overstoichiometric film composition was determined, with a C/ (metal Si) ratio of 1.5‒1.7 and added metal/Ti ratio of about 0.4‒0.5. All the coatings contained FCC nanocrystalline solid solution phases, with nanometer size crystallites (4.3‒7.1 nm). If compared to the 316 L steel substrate, the coatings exhibited superior corrosion behaviour. This fact is indicated by the more electropositive corrosion potential, the lower corrosion current densities and the higher polarization resistances. Combined effects of corrosive, adhesive and oxidative wear were considered to mainly contribute to coating damage under wear in corrosive environment. In the saline solution, the TiSiC-Cr coating was found to have better tribological performance than TiSiC-Cr coating, opposite to the results obtained in dry tribological tests. Therefore, for a proper selection of the alloying metal aiming to improve the performances of TiSiC protective coatings, one should consider the specific working conditions in the envisaged application.
Authors : M. Apreutesei1, C. Boissy1, N. Mary1, M. Arab Pour Yazdi2, A. Billard2, P. Steyer1
Affiliations : 1: MATEIS Laboratory-INSA de Lyon, Bât. B. Pascal, 7 Avenue Jean Capelle, 69621 Villeurbanne cedex, France 2: IRTES-LERMPS-UTBM, Site de Montbéliard, 90010 Belfort Cédex, France
Resume : Thin film metallic glasses are a new class of promising materials for advanced structural applications. In this work, binary Zr-based thin film metallic glasses (TFMGs) were deposited by the magnetron co-sputtering process from pure metal targets. Two similar enrichments were investigated (44 at.% for the nickel, 43 at.% for the cobalt), in order to determine the effect of the alloying elements nature on the structural, mechanical and electrochemical behaviors. Structure of films was determined by in situ XRD measurements carried out during heating up to 600°C, while their morphology was characterized by SEM observations. Mechanical properties of amorphous and crystallized films (hardness and Youngs modulus) were measured by nanoindentation. Intrinsic electrochemical properties are deduced from polarization curves and electrochemical impedance spectroscopy measurements carried out in Na2SO4 aqueous solution. It is found that the surface morphology of TFMGs were very smooth with a compact and dense microstructure. When heated, glassy films exhibit a high structural stability (up to 440 °C) with crystallization occurring through a multistage process for the Co-containing film. Whatever the coating, Zr affords its beneficial passive-ability, while crystallization process accelerates the global corrosion kinetics. Corrosion mechanisms of the Zr-based TFMGs were discussed in the light of the alloying element (Ni or Co) and the structure of films (amorphous or crystallized).
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Nanocomposites and nanostructured coatings : Part IV : Functional properties : T. Belmonte and F. Vaz
Authors : J. Borges1,2,3, M.F. Rodrigues3, L. Cunha3, M. Vasilevsky3, A. Cavaleiro2, T. Polcar1, T. Kubart4, F. Vaz2,3
Affiliations : 1 Department of Control Engineering, Faculty of Electrical Engineering, Czech Technical University in Prague, Technická 2, Prague 6, Czech Republic 2 SEG-CEMUC, Mechanical Engineering Department, University of Coimbra, 3030-788 Coimbra, Portugal 3 Centro/Departamento de Física, Universidade do Minho, Campus de Gualtar, 4710 - 057 Braga, Portugal 4 Solid-State Electronics, Department of Engineering Sciences, Uppsala University, P.O. Box 534, Uppsala SE-751 21, Sweden
Resume : The interest in nanocomposite materials containing those metal NPs embedded in dielectric matrices, such as TiO2 or Al2O3, is related with their potential use for a wide range of advanced technological applications, including colour filters, optical sensors, solar cells, photocatalytic antibacterial and pollutant-degradation materials, gas sensors and Surface Enhanced Raman Spectroscopy (SERS). Most of these applications, particularly, those in the decorative field, rely on the so-called localized surface plasmon resonance (LSPR) absorption, which is governed by the type of the noble metal NPs, their distribution, size and shape and as well as of the dielectric properties of the matrix. Results show that the annealing experiments enabled a gradual increase of the mean grain size of the Au NPs (from 2 to 23 nm), and changes in their distributions and separations within the dielectric matrix. For higher annealing temperatures of the as-deposited films, a broad size distribution of Au NPs was found (sizes up to 100 nm). The structural conditions necessary to produce LSPR activity were found to occur for annealing experiments above 300 ºC, which corresponded to the crystallization of the gold NPs, with an average size strongly dependent on the annealing temperature itself. The host matrix started to crystallize at an annealing temperature of about 500 ºC, which is an important parameter to explain the shift of the LSPR peak position to longer wavelengths, i.e. a red-shift.
Authors : R. J. Peláez, C.E. Rodríguez, C. N. Afonso
Affiliations : Laser Processing Group, Instituto de Optica, CSIC, Serrano 121, 28006 Madrid, Spain
Resume : Nanoparticles (NPs) of noble metals on surfaces or embedded in dielectric hosts give rise to interesting optical responses related to collective oscillations of free electrons. They lead to surface plasmon resonances (SPR) in the visible part of the spectrum that give rise to intense colours, thus becoming attractive for decorative coatings. One of their appealing properties is the possibility to tune the optical response or colour through parameters such as the size or shape of the NPs as well as their spacing or proximity. In this work we demonstrate that surface treatment of multilayer thin films (thickness <20 nm) with single UV nanosecond laser pulses is an easy-to-use tool for tuning the NPs optical response in a wide spectral range. We have selected a bilayer system (Au & Ag) on glass substrates and used single layers of Ag or Au for comparison. As film parameters, we have studied the deposition order and the composition by varying the thickness of the Au layer while keeping that of Ag constant. As laser parameter, we have varied the fluence. The samples are optically and structurally characterized by extinction spectroscopy and scanning electron microscopy, respectively. The laser treatment produces mixing of the two metals and NPs with a diameter that depends on the total amount of metal. Depending on fluence, the interparticle distance can become comparable to the NPs diameter and multipolar interactions dominate the optical response.
Authors : D. Craciun1, D. Cristea2, M. Stoicanescu2, E. Lambers3, G. Socol1, V. Craciun1
Affiliations : 1National Institute for Lasers, Plasma and Radiation Physics, Magurele, Romania; 2Materials Science Department, Transilvania University, Brasov, Romania; 3MAIC, University of Florida, Gainesville, USA
Resume : LaB6 is a refractory compound that is well known for its very low work function. It has been mainly used for electron emitting devices working at high temperatures in vacuum. We depos-ited LaB6 films on Si substrates at 500 deg. C under ultrahigh vacuum conditions using the pulsed laser deposition technique. The structure was investigated by grazing incidence and symmetrical X-ray diffraction. The use of a high laser fluence (~7 J/cm2) during deposition re-sulted in the synthesis of slightly textured films along (100) axis, with small crystallite sizes and rather high level of microstresses. X-ray reflectivity investigations showed that films were very dense and smooth, while X-ray photoelectron spectroscopy found that films were almost stoichiometric and contained a low amount of oxygen. Four point probe measurements showed that films exhibited very good electrical conductivity, below 100 micro-ohm.cm. Nanoindentation and scratch tests found that films were hard, adherent, and exhibited low friction coefficients. All these characteristics recommend the LaB6 films for usage as sliding electrical contacts operating under vacuum and/or extreme temperatures.
Design of novel thin films for energy conversion, save and storage : T. Kubart & D. Mariotti
Authors : P.J. Dale
Affiliations : Laboratory for Energy Materials, Physics and Materials Science Unit, University of Luxembourg
Resume : In order for thin film photovoltaic devices to contribute to future renewable energy generation they must consist of earth abundant materials and be cheap to manufacture. At the heart of thin film photovoltaic devices lies the p-type semiconductor absorber layer whose job is to convert incoming solar radiation into electrical charge carriers that are subsequently separated across the p-n junction. The leading earth abundant thin film absorber layer is Kesterite, Cu2Zn(Sn,Ge)(S,Se)4, which has produced laboratory scale power conversion efficiencies of around 12 %, close to the necessary efficiency for thinking about industrial production. Here, the current status of Kesterite technology will be reviewed in terms of desired and achieved properties and the synthetic challenges which must be overcome to improve overall device efficiency. Amongst the key semiconductor properties for thin film absorber layers are band gap, doping density and minority carrier life. Additionally, attention to layer integrity and the presence of detrimental secondary phases is of equal importance. The quaternary Kesterite has a rather small single phase region and multiple secondary phases are possible. Also, under normal synthesis conditions it releases two volatile species that must be taken into account for any controllable synthesis. Given these challenges, and with a perspective to depositing films on a meter squared basis, a close examination of Kesterite layer growth strategies is required.
Authors : D.Aureau,C.Njel,A.-M.Goncalves,A.Etcheberry
Affiliations : Institut Lavoisier de Versailles UMR 8180, Université de Versailles-St-Quentin en Yvelines, 45 avenue des Etats Unis, 78000 Versailles, France
Resume : III-V semiconductors represents ideal candidates for several applications. However, the spontaneous oxidation in air leads to the loss of its electrical properties. The surface passivation becomes a key step for its integration in attractive devices. In this work, the electrochemical passivation of III-V semiconductors is evidenced in liquid ammonia ( 55 °C) during an anodic treatment as alternative ways for nitrogen (N2+) ion bombardment procedure or N2 plasma technique. We reproducibly realized the formation of a polyphosphazene-like (H2N-P=NH)n film on InP. The monitoring of the film formation was performed using a systematic coupling between electrochemical measurements and X-ray photoelectron spectroscopy. Detailed analysis show the growth mechanism of the film starting from nucleis up to a complete coverage. The lowest charge required to guarantee full coverage of InP by the film is determined (~ 0.5mC/cm2) which shows that only some layers of InP are involved (density of surface atoms=1015/cm2). The study of the air ageing or the evolution in contact with strong oxidants of the modified surface revealed the chemical protection of the surface by the film. This tremendous stability is also in accordance with the high level of luminescence. PL measurements show that really few interface states are created upon film formation. Promisingly, the film prevents the decrease of luminescence in long periods of time suggesting the maintaining of a good interface.
Authors : E. Symeou 1*, C. N. Mihailescu 1, 2, M. Pervolaraki 1 and J. Giapintzakis 1*
Affiliations : 1 Nanotechnology Research Center and Department of Mechanical and Manufacturing Engineering, University of Cyprus, 75 Kallipoleos Av., PO Box 20537, 1678 Nicosia, Cyprus 2 National Institute for Laser, Plasma and Radiation Physics, 409 Atomistilor St., PO Box MG-36 077125, Magurele, Romania
Resume : Nowadays there is a strong belief that thermoelectric thin film-based devices represent a suitable route to mitigate thermal management problems in micro- and nano-electronics. Bi0.5Sb1.5Te3 is considered to be a state-of-the-art p-type thermoelectric material, at temperatures near room temperature, due to its high power factor value. We have grown p-type Bi0.5Sb1.5Te3 thin films onto different types of substrates using pulsed laser deposition at 248nm and home-made targets with different Bi concentrations, and investigated their structural, electrical and thermoelectrical properties. In this talk, we will present our recent results on Seebeck coefficient, electrical resistivity and Hall carrier concentration as a function of temperature for a series of Bi0.5Sb1.5Te3 thin films. We will discuss how their thermoelectric properties are affected by the substrate type and Bi content. Also, we will address the effect of post-annealing treatment on their structural and thermoelectric properties.
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Atmospheric process, organic synthesis and surface functionalization : J.F. Pierson & T. Kubart
Authors : Davide Mariotti
Affiliations : NIBEC - University of Ulster
Resume : Non-thermal atmospheric pressure plasmas (APPs) have attracted great interest due the potential cost reductions in manufacturing and processing of materials for a wide range of applications. Although APPs present several challenges, considerable progress has been achieved in recent years with an increasing number of industrial and commercial applications utilizing different forms of APPs. One of the most attractive applications of APPs is for the synthesis and processing of nanomaterials with specific focus on materials for energy applications. In this contribution we will present recent advances in both the synthesis and surface engineering of a range of materials including metal, metal-oxides and quantum confined silicon-based nanoparticles. We will then discuss the integration of such materials and low-cost APP-based processes for the fabrication of photovoltaic devices, demonstrating their contribution and potential for an all-APP fabrication sequence. Device parameters will be presented and analysed for different device architectures. Finally, we will show also how APP-based surface engineering can also offer great opportunities for tailoring surface properties of nanoparticles and contribute to further our scientific understanding of nanosystems.
Authors : Anton Manakhov(1), Rony Snyders(2,3), Damien Cossement(3), Miroslav Michlicek(1,4), Jan Cechal(5), David Necas(1,4), Lenka Zajickova(1,4)
Affiliations : (1) Plasma Technologies, CEITEC Central European Institute of Technology, Masaryk University, Brno, Czech Republic; (2) Chimie des Interactions Plasma Surface (ChIPS), CIRMAP, Université de Mons, Mons, Belgium; (3) Materia Nova Research Center, Parc Initialis, Mons, Belgium; (4) Department of Physical Electronics, Faculty of Science, Masaryk University, Brno, Czech Republic; (5) CEITEC - Central European Institute of Technology, Brno University of Technology, Brno, Czech Republic
Resume : Stable amine-rich plasma coatings have numerous important applications including cell adhesion enhancement and biomolecule immobilization. The bioapplication of plasma coatings requires sufficient layer stability in water in order to avoid leaching of toxic oligomers and increase the durability of the deposited coating. For majority of monomers used for plasma polymerization of amine coatings (allylamine, ethylemediamine, ammonia/ethylene), the increase of the coating stability was obtained at the expense of the surface concentration of amines. Recently, it was found that amine-rich cyclopropylamine (CPA) plasma polymers exhibited extremely low thickness loss (1-2%) combined with 9 at.% of NHx environment if the substrate is DC self-biased. Hence, the stability was sufficiently improved compared to previous results (thickness loss of 20%, NHx of ~10 at.%) where the substrate was at a floating potential. The IR spectroscopy and Time-of-Flight Secondary Ion Mass Spectroscopy (ToF-SIMS) combined with principal component analysis (PCA) were employed to investigate the crosslinking degree of the CPA plasma polymers. According to IR data, the layers deposited at floating potential exhibited higher intensities of nitriles and lower intensities of hydrocarbons. PCA analysis of ToF-SIMS data revealed that the layers deposited at DC self-bias has higher C/H ratio and therefore, higher crosslinking degree. Hence, the deposition at DC self-bias allowed to improve the layer stability without large sacrifice of the amine concentration.
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