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2015 Fall

Nanomaterials,Nanostructures and Nano devices


Colloidal Assembly of Functional Nanomaterials: from assembly routes to functional device

The assembly of nanoparticles into complex and functional superstructures is key to achieving tailor-made materials with functional properties at the nanoscale. Novel synthesis strategies that include various classes of building blocks give rise to advanced nanomaterials like photonic crystals, multifunctional carriers for drug delivery or elaborate superlattice structures. 




This symposium explores novel strategies for the assembly of functional nanomaterials. Methods for the synthesis of nanostructures include the self-assembly of functional nanoparticles, the formation of polymer-nanoparticle hybrids, or bio-inspired processes like mesocrystal formation.

Carbon nanomaterials are a prime example of building blocks for the assembly of functional nanomaterials, such as graphene-based sensors, drug delivery carriers based on nanodiamond or photoelectrodes made from arrays of nanotubes in combination with TiO2 particles. Further building blocks are functional nanoparticles like quantum dots, mesoporous silica, superparamagnetic iron oxide or anisotropic and patchy nanoparticles. One especially exciting development of the last years is the emergence of superlattice structures based on nanoparticles with conjugated DNA-linkers, which enable the assembly of nanoparticle superstructures in a molecular-chemical approach. Another point of interest is the formation of hybrid nanomaterials assembled from a combination of nanoparticles and polymers, including bionanocomposites.

Application areas for assembled nanostructures can be found in diverse and critical fields: in drug delivery, multifunctional drug carriers are assembled from mesoporous silica or other functional nanoparticles; lab-on-a-chip devices utilize functionalized nanoparticle arrays for improved diagnostic capabilities; photovoltaics benefit from tailored nanostructured surfaces; photonic crystals are used to enhance optical devices; carbon nanomaterials begin to find their way into next generation electronics and the field of tissue engineering drives the development of materials with fine control over nanotopographical features, especially regarding the assembly of three dimensional fibrous nanostructures which are found in many natural tissues. 


Hot topics to be covered by the symposium:


Contributions will address the following topics which are corresponding to possible topical sessions: 

  • Functional Nanostructures
  • Hierarchical Materials
  • Nanoparticle Self-Assembly
  • Colloidal Crystals/Mesocrystals
  • Photonic Crystals
  • Superlattice Structures
  • Colloidosomes and other Multifunctional Microcapsules
  • Bionanocomposites
  • Nanostructured Substrates for Tissue Engineering
  • Assembly of Carbon Nanomaterials
  • Colloidal Processing of Nanostructured Ceramics


Invited speakers:


  • German Salazar-Alvarez, Stockholm University, Sweden
  • Jan Lagerwall, University of Luxembourg
  • Anna Roig, Materials Science Institute of Barcelona, Spain
  • Francisco Fernandes, Université Pierre et Marie Curie, France
  • Erik Reimult, University of Natural Resources and Life Sciences, Vienna, Austria
  • Andrés Guerrero Martínez, Complutense University of Madrid, Spain
  • Xuehua Zhang, RMIT University, Melbourne, Australia
  • Joachim Bill, Stuttgart University/MPI for intelligent Systems, Stuttgart, Germany
  • Sylvain Deville, CNRS, Cavaillon, France


Tentative list of scientific committee members


  • Fiona Meldrum, University of Leads, UK
  • Markus Niederberger, ETH Zurich, Switzerland
  • Ulrich Simon, RWTH Aachen, Germany
  • Markus Antonietti, MPI for Colloids and Interfaces, Potsdam, Germany
  • Janne Roukolainen, Aalto University School of Science, Finland
  • Liberato Manna, Istituto Italiano di Tecnologia, Genova, Italy
  • Frank Caruso, University of Melbourne, Australia
  • Gustaaf van Tendeloo, University of Antwerp, Belgium
  • Dean Ho, UCLA School of Dentistry, USA
  • Marie-Helene Delville, Institute of Chemistry-CNRS, Bordeaux, France
  • Luis Liz-Marzan, University of Vigo, Spain
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Authors : C. Garozzo, K. Brassat, A. La Magna, R.A. Puglisi, J.K.N. Lindner
Affiliations : CNR- Instituto per la Microelettronica e Microsistemi, 95121 Catania, Italy; Universität Paderborn, Departmet of Physics, 33098 Paderborn, Germany

Resume : Nanoparticles of Au play an important role in the functionalization of surfaces, as they can be used as catalysts for the growth of semiconductor nanowires, plasmonic particles, metal enhanced etching etc. In many of these applications it is essential to control the arrangement and distance of these particles at specific sites on the surface, to control their shape and to fix the position in subsequent processing steps. Au nanoparticles can be obtained in large quantities as colloidal particles in aqueous suspensions which can be easily employed to functionalize surfaces. In this contribution we demonstrate a novel approach to tailor the arrangement of such colloidal Au nanoparticles on a SiO2/Si surface. Block-copolymer lithography using PS-b-PMMA was used to create periodic surface patterns consisting in hexagonally close-packed vertical cylinders. The pattern was transferred into the SiO2 surface thin film using reactive ion etching, resulting in a hexagonal arrangement of 20 nm diameter pores. A doctor blade technique was used to spread colloidal suspensions of 5 and 10 nm Au particles on the surface. It is shown using electron microscopy that at appropriate conditions, Au nanoparticles can be positioned selectively in the pores with up to 88 % of pores being occupied with nanoparticles. This new technique may pave the way for a controlled application of colloidal Au nanoparticles in various technological areas.

Authors : Emanuele Marino, Thomas E. Kodger, Benjamin Bruhn, Tom Gregorkiewicz, Katerina Dohnalova and Peter Schall
Affiliations : Van der Waals-Zeeman Institute, Institute of Physics, University of Amsterdam, Science Park 904, 1098 XH Amsterdam (The Netherlands);

Resume : A major challenge in the development of highly efficient semiconductor quantum dot-based solar cells is controlling the energy transfer between adjacent nanocrystals. This is partly due to the lack of precise, yet large-scale, control in nanoscopic dimensions, which is required to achieve a close packed and uniform superstructure [1]. We study the assembly of quantum dots in a binary mixture which exhibits temperature dependent solvent fluctuations; remarkably, these induce reversible assembly even at the nanoscale. This technique allows us to finely tune the distance between the dots by simply playing with the temperature and the Debye screening length in the solution. By doing so, we observe the spectral fingerprint of inter-dot coupling as the nanostructure grows with time. [1] Liu, Yao, et al., "Dependence of carrier mobility on nanocrystal size and ligand length in PbSe nanocrystal solids" Nano Lett. 10 (5), 1960-1969 (2010).

Authors : Corinna Kaulen, Melanie Homberger, Ulrich Simon
Affiliations : Institute of Inorganic Chemistry, RWTH Aachen University, 52074 Aachen, Germany

Resume : Among nanostructured materials, gold nanoparticles (AuNP) hold promise for novel applications in nanoelectronics.[1] For such kind of applications AuNP are easily accessible nanoscale building blocks with tailored surface properties. This allows for controlled assembly of the AuNP e.g. on electrode materials, which is a crucial step for electrical addressing. According to this, we recently reported the directed self-assembly AuNP, which carry either amine- or carboxylic acid terminal groups in their ligand shell, on platinum and gold/palladium alloy electrodes, respectively.[2] We showed that their selective adsorption on only one electrode type, which is quantified by the covering density, is achieved by choosing the appropriate pH and ionic strength. In this work we introduce that the adsorption of the charged AuNP is sensitive to the ion composition present in the electrolyte solution as well, which has similarities to the influence of salt additions on protein precipitation, as described by Hofmeister.[3] Enhanced electrode covering density can be achieved, when small, strongly hydrated ions are present, while large ions with just a weak hydration shell lead to lower covering density. This demonstrates for the first time that not only the terminal functional group of the ligand shell but also the composition of the electrolyte is an effective parameter to control the assembly of AuNP on electrodes or metal surfaces in general. [1] Homberger, M.; Simon, U. Phil. Trans. R. Soc., A 2010, 368, 1405−1453. [2] Kaulen, C.; Homberger, M.; Babajani, N.; Karth?user, S.; Waser, R.; Simon, U. Langmuir 2014, 30, 574-583. [3] Hofmeister, F. Arch. Exp. Pathol. Pharmakol. 1888, 24, 247.

Authors : Olivier Deschaume, Chris Van Haesendonck, Carmen Bartic
Affiliations : Laboratory for Soft Matter and Biophysics, KU Leuven, Celestijnenlaan 200 D, B-3001 Leuven, Belgium; Laboratory of Solid State Physics and Magnetism, KU Leuven, Celestijnenlaan 200 D, B-3001 Leuven, Belgium; Laboratory for Soft Matter and Biophysics, KU Leuven, Celestijnenlaan 200 D, B-3001 Leuven, Belgium

Resume : Protein-based scaffolds enable flexible and sustainable approaches to produce and manipulate materials at the nanometer scale [1]. The underlying self-assembly principles can complement classical top-down fabrication techniques to answer current challenges and needs in applications including biosensing or regenerative medicine. Amyloid protein nanofibres prepared from hen egg white lysozyme have been found to mediate the assembly of gold nanoparticles into 1D-arrays from solutions to silicon oxide surfaces [2]. The effect of experimental conditions on the self-assembly process is discussed based on atomic force microscopy and UV-visible spectroscopy measurements. The correlation between measured interparticle distances and results of DLVO calculations demonstrates a strong impact of electrostatic interactions on self-assembly. The deposited particles are then used as surface-immobilised seeds for the surfactant-assisted growth of metal structures with a wide range of morphologies. The experimental results are finally correlated with FDTD simulations to understand further the effect of particle spacing and morphology on the optical properties of the surface-deposited biohybrid materials. 1. F. Leroux, M. Gysemans, S. Bals, K. J. Batenburg, J. Snauwaert, T. Verbiest, C. Van Haesendonck, G. Van Tendeloo, Adv. Mater., 2010, 22(19), 2193-7. 2. O. Deschaume, B. De Roo, M. J. Van Bael, J.-P. Locquet, C. Van Haesendonck, and C. Bartic, Chem. Mater., 2014, 26, 5383-93.

Authors : B. P. Pichon, D. Toulemon, S. Bégin-Colin
Affiliations : Institut de Physique et de Chimie des Matériaux de Strasbourg 23, rue du Loess - BP 43, 67034 STRASBOURG Cedex 2

Resume : The assembling of magnetic nanoparticles into arrays represents a very exciting and important challenge with regards to their high potential in the development of new nanodevices for spintronic, magnetic and magneto-electronic applications. The physical properties of nanoparticle assemblies being significantly dependent on their spatial arrangement, it is well argued that the key to successful applications of such nanoparticle-based devices is engineering well-defined nanostructures. Magnetic properties are strongly dependent on dipole-dipole interactions and can be finely tuned by controlling the interparticle distance and dimensionality of assemblies. Here we report on the assembling of nanoparticles on planar surfaces by using different bottom-up approaches such as the Langmuir-Blodgett technique and assembling promoted by specific chemical interactions between nanoparticles and substrates by taking advantage of click chemistry. Depending on the experimental conditions, nanoparticle assemblies consist in multilayers (3D), monolayers (2D), chain-like structures (1D) or isolated nanoparticles. Such a control on the dimensionality of assemblies enables us to study systematically the influence of shape anisotropy on the collective properties of magnetic nanoparticles. Shape anisotropy is also modulated as function of the interparticle distance which has a strong influence on dipolar interactions.

Authors : I. Shupik,1,2 L. Vauriot,1,2 JP Delville,2 MH Delville,1 *
Affiliations : 1 Institut de Chimie de la Matiere Condensee de Bordeaux, CNRS UPR 9048, Universite of Bordeaux 87 Avenue du Dr Schweitzer F-33608 Pessac Cedex FRANCE (*email: 2 Laboratoire Ondes et Matière d'Aquitaine (UMR 5798), Université de Bordeaux/CNRS, 351 Cours de la Liberation, 33405 TALENCE Cedex FRANCE

Resume : During the last decade, there has been a tremendous interest in Janus particles with more than 1500 papers on synthesis, production yield, and more recently functionalisation, self-assembly and applications. However, these reports mainly concern associations between two polymers, a polymer and metal or metal oxide, and a metal with a dielectric metal oxide. Samples based on metal/semiconductors are scarce. Additionally, most of these production methods are time consuming on the one hand and produce rather low quantities of particles on the other hand. It seems crucial to implement a technique which circumvents these drawbacks and setup a simple device which allows a facile production of significant amount of Janus nanoparticles. In this context, we present a general and flexible optofluidics strategy in lab-on-chip. The concept consists in activating the band gap of flowing semiconductor nanoparticles by a Laser to generate electron-hole pairs and use electrons to photoactivate the redox transformation of an active ion present in the flowing solution. Nano TiO2 is an oxide of choice due to its extended use, high stability, low cost, and UV activity. Controlled synthesis of TiO2 nanoobjects with various morphologies will be detailed as well as their laser dissymetrisation by metals (Ag, Au) when varying the different parameters of photodeposition in the microchannel: chemical ones (nature of the TiO2 NPs, choice of metal precursor, pH of the solution, right ratio between reactants), physical ones (choice of beam power, size of the µchannel and flow rate of NPs).1 The generalisation of this approach to other types of semiconductors/metal nanoparticles such as ZnO will be illustrated. It can enlarge the field applications. 1. Delville, M.-H.; Delville, J.-P.; Vauriot, L. Dissymmetric particles of TiO2 (Janus particles) and method for synthesizing them by photodeposition. WO2014096675A1, 2014.

Authors : B. Kalska-Szostko*, U.Wykowska*, D. Satuła#
Affiliations : * Institute of Chemistry, University of Bialystok, Hurtowa 1, 15-399 Białystok, Poland #Department of Physics, University of Bialystok, Ciolkowskiego 1L, 15-245 Białystok, Poland

Resume : Since few decades studies of different kind of nanostructures become very fashionable. However, in last time, combination of the nanoparticles with organic compounds become one of the most popular subject. It happened because of wide potential application of such bionanocomposites. In fabrication process first of all, proper surface characteristic of nanoparticles is needed, what then allows for immobilization of the biological structures. Linking both spices one results with preparation of new, unique heterostructure with desired/mixed functionality. Metallic nanoparticles might be directly combined with biological compounds or via additive linkers which form organized monolayer or rather random structure on the nanoparticles surface [1]. Nanocomposites based on magnetic nanoparticles has a huge advantage over nonmagnetic one, due to its easy handling possibility with use of external magnetic field. Application of such a manipulation tool is of extremely importance because it allows to simplify control of particles specific interaction with living cells. In this presentation, magnetic nanoparticles were immobilized with enzymes such as albumin, glucose oxidase, lipase, and trypsin, with or without previous surface modification. Characterization of the nanoparticles was done by Transmission Electron Microscopy, X-ray diffraction and Mössbauer spectroscopy. The effect of obtained biocomposites was monitored by FTIR. [1] C. Yee, G. Kataby, A. Ulman, T. Prozorov, H. White, A. King, M. Rafailovich, J. Sokolov, A. Gedanken, Langmuir 15 (1999) 7111-7115

Authors : Tobias Wernicke, Matthias Schuster, Stefan A. Möckel, Ulrike Künecke, Peter J. Wellmann
Affiliations : Materials Department 6 (i-meet) FAU Erlangen Nürnberg Martnesstr. 7 91058 Erlangen, Germany

Resume : Se nanoparticles were synthesized for the application of local bandgap tailoring by self assembled deposition of colloidal dispersions onto ZnS as well as chalcopyrite (CuInS2) and kesterite (Cu2ZnSnS4) compound semiconductors surfaces. Within this report, the focus is put on the processing route and stabilization of the nanoparticulate ink which is a prerequisite for any defined, subsequent materials functionalization. Se nanoparticles of ca. 80 nm in size were synthesized by chemical reduction of 0.1267 mol/l Na2SeSO3 using HCL. Two approaches for the colloidal ink formulation of Selenium (Se) nanoparticles were followed. The produced particles were stabilized using polyvinylpyrrolidon (PVP) and micelles (TX100) in varying concentrations. It was found that both approaches lead to stable colloidal suspensions. Both were further processed to high concentration printable precursors. Dynamic light scattering was applied in order to monitor the processing of the Se suspensions with respect to particle size and colloidal stability. UV/VIS spectroscopy and Lambert-Beer's law were used to quantitatively determine the concentration of Se in the dispersion. For this reason, in order to calibrate the optical measurement method, the molar extinction coefficient ε of Se was determined at a specific wavelength.

Authors : Marie-Hélène Delville1*, Quentin Le Trequesser1,2, Guillaume Devès2, Gladys Saez2, Laurent Daudin2, Philippe Barberet2,, Claire Michelet2and Hervé Seznec2
Affiliations : 1 CNRS, UPR9048, (ICMCB), France, 2 Université de Bordeaux, (CENBG) France

Resume : Nanoparticles are produced for decades on industrial scale, there is an urgent need to evaluate their risks and ensure their safe production, handling, use, and disposal. Moreover, a comprehensive study is clearly needed to fully explore their toxicity, which may help to better understand their deleterious health effects and create environmentally friendly and biologically relevant nanoparticles. In particular, the behaviour of nanoparticles inside living cells is still an enigma. Toxicity is among others a dose-dependent phenomenon. It is then crucial to be able to set-up methods susceptible to quantify NPs from macro- to sub-cellular scales. This presentation concerns this aspect since we propose: 1) to apply Multimodal Correlative Microscopy based on Ion Beam Analysis, TEM, and Confocal Microscopy to detect, track, and quantify of bare and chemically modified TiO2 NPs and also use them as indicators of ion homeostasis, cell metabolism, or fate. [] 2) to address their potential toxicity on organisms such as C. elegans (Nematode). In this context, we studied the ecotoxicological effects of three different types of bare or hybrid TiO2-NPs on C. elegans.[] Their impact was investigated using several parameters: survival, worm length, and reproduction. Project funded by ANR: TITANIUMS

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Authors : Dymtro Dedovets1,2, Satyabrata Si1, Emilie Pouget2, Jiaji Cheng2 Sabrina Habtoun3, Said Houmadi3, Christian Bergaud3, Reiko Oda2, Marie-H?l?ne Delville1
Affiliations : 1 Institut de Chimie de la Matiere Condensee de Bordeaux, CNRS UPR 9048, Universite of Bordeaux 87 Avenue du Dr Schweitzer F-33608 Pessac Cedex FRANCE (*email: 2 CBMN, All?e Geoffroy Saint Hilaire, B?t B14, 33600 Pessac

Resume : In the field of emerging nanoscale materials with switchable properties chiral structures like helices or twisted ribbons are of great interest because of their intrinsic optical and mechanical properties. In this contribution, we present a study about the mechanical properties of SiO2 and SiO2@MxOy nanotubes and helical nanosprings synthesized by an original and simple technique from organic nanotubes through inorganic transcription. These nano-objects have potential applications in NEMS, ranging from physical sensing and signal processing to ultra-low power radio frequency signal generation, thanks to their striking features. NEMS have been generally based on 1D nano-objects, such as carbon nanotubes or silicon nanowires. However, the use of 3D nanostructures such as nanohelices would allow a significant improvement the electromechanical performances of functional nanodevices, due to their specific properties. The originality of our synthesis method consists in the possibility to obtain 3D nanostructures with specific morphology and properties. Hybrid nano-helices are synthesized using amphiphilic organic chiral self-assemblies forming very well defined helix or ribbons structures and exploits them as templates for inorganic nanomaterial formation[1]. Their bio-inspired mineralization creates silica nano-helices with very well controlled morphologies usable in functional nanodevices such as sensors, actuators and resonators. To the best of our knowledge, nothing has been

Colloidal assembly of functional nanomaterials: from assembly routes to functional devices Part vi : Francisco M. Fernandes
Authors : G. Salazar-Alvarez, M. Agthe, E. Wetterskog, L. Bergström
Affiliations : 1Materials and Environmental Chemistry, Stockholm University, Sweden; 2Dept. of Engineering Sciences, Uppsala University, Sweden

Resume : Previously we have presented the rich phase diagram of large, well-ordered three-dimensional mesocrystals based on truncated iron oxide nanocubes (IONs).[1] Where we showed that extracting detailed information from small-angle x-ray scattering (SAXS) and electron microscopy measurements allows the reconstruction of the dominant phases.[2] In this talk we present the time-dependent growth of ION mesocrystals on flat substrates studied by image analysis. It is found that the quasi 2D-growth of the individual mesocrystals can be approximated by single exponential functions, whereas the total conversion rate adopts a sigmoidal character, similar to conversion curves for crystallizing polymers. Moreover, we have followed the self-assembly IONs by time-resolved SAXS experiments on levitating droplets. The acoustic levitator enables substrate-free evaluation of reaction kinetics within a droplet and on the liquid-air interface. Several stages during droplet drying can be identified from transitions in the scattering behaviour and correlated with existing nucleation theories. [1] L. Bergström, E. Sturm, G. Salazar-Alvarez, H. Cölfen, Acc. Chem. Res. 48 (2015) 1391. [2] a) S. Disch et al. Nano Lett., 11, 1651-1656 (2011). b) S. Disch et al., Nanoscale 5 (2013) 3969. c) Wetterskog et al., Sci. Technol. Adv. Mater. 15 (2014) 055010.

Authors : Shinji Kuroda
Affiliations : Institute of Materials Science, University of Tsukuba

Resume : In the search of novel magnetic semiconductors, an attempt to incorporate magnetic element in a high content often results in a phase separation into regions with high and low contents of magnetic elements. There are two types of phase separation; the aggregation of magnetic elements with keeping crystal structure coherent to the host semiconductor (chemical phase separation) and the precipitation of nanocrystals of an extrinsic phase (structural phase separation)[1]. In this presentation, we will show our recent experiments on the phase separation and its correlation with magnetic properties in II-VI magnetic semiconductors (Zn,Cr)Te and (Zn,Fe)Te, which were grown by molecular beam epitaxy. In (Zn,Cr)Te, it is found that the co-doping of iodine as a donor impurity enhances the phase separation[2]. With the increase of Cr content or the growth temperature, the type of phase separation changes from chemical to structural phase separation[3]. In (Zn,Fe)Te, the growth with a surplus supply of Zn flux over Te flux induces the formation of Fe-rich columnar regions, which appear to be structurally coherent to the host crystal[4]. Details will be presented at the conference. [1] T. Dietl et al., Rev. Mod. Phys., in press. [2] S. Kuroda et al., Nat. Mater. 6, 440 (2007). [3] H. Kobayashi et al., Physica B 407, 2947 (2012). [4] S. Ishitsuka, Phys. Stat. Sol. (c) 11, 1312 (2014).

Authors : V.D. Popovych*, P.Sagan, M.Bester, B. Cieniek, I. Stefaniuk, M. Kuzma
Affiliations : Faculty of Mathematics and Natural Sciences, Department of Experimental Physics University of Rzeszow, Pigonia 1, 35-959 Rzeszow, Poland. *Department of Fundamental Technologies, Ivan Franko Drogobych State Pedagogical University, 24 Ivan Franko str., 82100, Drogobych, Ukraine

Resume : Cr-doped CdTe crystals were theoretically predicted to be DMS with high Curie temperature due to superexchange spin interaction between nearest-neighbor Cr2 ions substituted cadmium atoms in the host lattice [1]. However, it was also reported that room-temperature ferromagnetism in Cr-based AIIBVI compounds could possibly be associated with precipitation of dopant-related secondary phases [2] caused by poore chromium solubility in the host matrix. In the present work we investigated CdTe:Cr single crystals grown by physical vapour transport method from pre-synthesized (Cd,Cr)Te alloys with 2.5 and 5 at.% of chromium nominal content. Arranged sets of extrinsic phase precipitates were revealed by means of SEM patterning of the (110)- and (111)-oriented surfaces of the crystals, both in the form of nm-sized near-isometric particles and platelets with sub-μm thickness. Using EDX profiling, HAADF elemental mapping and HRTEM measurements coupled with FFT images analysis, it was determined that the observed defects are composed of Cr-Te intermetallic compounds coherent with {111} and {100} planes of the zinc-blende structure of CdTe environment. Magnetic properties of the grown crystals were studied by means of EPR data obtained using X-band Bruker spectrometer (9.43 GHz). The angular dependence of spectrum showes two sets of fine components originated from substitution Cr2 ions in the CdTe host matrix and from precipitated CrTe-related phases. [1] J. Blinowski, P. Kacman, J.A. Majewski, J. Cryst. Growth. 159 (1996) 972. [2] Sreenivasan, M.G., Teo, K.L.; Cheng, X.Z.; Jalil, M.B.A.; Liew, T.; Chong, T.C.; Du, A.Y.; Chan, T.K.; Osipowicz, T.,Structural, magnetic, and transport investigations of CrTe clustering effect in (Zn,Cr)Te system, Journal of Applied Physics, v 102, n 5, 2007, p 053702

Authors : Ye Yuan, Hua Cai, Manfred Helm, Shengqiang Zhou
Affiliations : Helmholtz-Zentrum Dresden-Rossendorf

Resume : Dilute magnetic semiconductors (DMSs) attracted great interests in the last several decades because of their potential for spintronic device [1]. III-V compounds especially GaAs based DMS has recently emerged as the most popular material for this new technology. However, that the low mobility of holes in p-type DMS limits the potential application in semiconductor spintronic devices. Therefore, the searching for n-type DMS is of interest. The doping of Fe in InAs is attracting research attentions due to the possibility to fabricate n-type diluted magnetic semiconductors [2, 3]. However, the low solubility of Fe in InAs is the most difficulty to achieve InFeAs DMS. In this work, we obtain Fe doped InAs layers by ion implantation and pulsed laser annealing. This approach has shown success for preparing other III-V based DMSs [4, 5]. The formed InFeAs layers are proved to be epitaxial-like on InAs substrates. The prepared InFeAs layers reveal similar magnetic properties independent of their conductivity types. While the samples are lacking of charactersistics of DMS, they appear to be superparamagnetic behavior, revealing such as time-dependent magnetiszation measurements reveal aging and memory effects. 1. T. Dietl et al., Science 287, 1019-1022 (2000) 2. M. Kobayashi et al., Appl. Phys. Lett., 105, 032403(2014) 3. P. Nam Hai et al., Appl. Phys. Lett., 101, 182403 (2012) 4. D. B?rger et al., Phys. Rev. B, 81, 115202 (2010) 5. M. Khalid et al., Phys. Rev. B, 89, 121301(R

Authors : Bao-Hsien Wu, Wei-Ting Liu, Lih-Juann Chen
Affiliations : National Tsing Hua University

Resume : Nowadays, the energy and environmental issues have become increasingly important. To convert sustainable energy into chemical fuels, the photocatalytic hydrogen production by semiconductor materials have received a great deal of attention. On the other hand, in order to develop efficient photocatalysts, two important factors must be taken into consideration: shifting the light absorption range to visible light and increasing the photogenerated charge carriers. Recent studies have shown that by introducing plasmonic metal, the photocatalytic efficiency of semiconductor can be improved via plasmon-enhanced light absorption. In the present work, we have successfully synthesized hexagonal close-packed core-shell Au/TiO2 hybrid nanocrystal arrays by a facile process, which includes arrangement of hexagonal close-packed metal nanocrystal arrays and deposition of TiO2 by atomic layer deposition (ALD). The localized surface plasmon resonance (LSPR) properties of the hybrid nanocrystal arrays have been investigated, which is consistent with the simulation based on Mie theory. Through tuning the thickness of TiO2 shell or changing the size of Au core, the LSPR wavelength can be systematically controlled. The hybrid Au/TiO2 nanocrystal arrays were then employed as photocatalysts in aqueous methanol solution. In comparison with bare TiO2 thin film, the hybrid Au/TiO2 nanocrystal arrays indeed exhibited notable increases in the amount of hydrogen from methanol solution splitting under both ultra-violet and visible light, which is attributed to the plasmon-enhanced light absorption. Based on finite difference time domain (FDTD) simulation, the electric field in TiO2 has been enhanced by LSPR, hence increased the generation of electron and hole pairs.

Authors : E.D. Glowacki,1 M. Sytnyk,2 Z. Bozkurt,2 N. S. Sariciftci,1 W. Heiss2
Affiliations : 1. Physical Chemistry, Johannes Kepler University, Linz, Austria 2. Institute of Materials for Electronics and Energy Technology (i-MEET) Friedrich- Alexander-University Erlangen-Nuremberg, Erlangen, Germany; and Energie Campus Nurnberg (EnCN), Nurnberg, Germany

Resume : Here we describe processes to transform archetypical commercial organic pigments into colloidal micro and nanocrystals suitable for solution processing of high-quality transistors, biosensors, and photosensors. Our methodology relies on ligand-mediated syntheses, transforming industrial colored pigment powders into stable colloidal solutions of semiconductor nanocrystals, highly suitable for electronic device developments. Tuning of process conditions can yield nanocrystals with zero, one-, two- and three-dimensional shapes, exhibiting a wide range of optical absorption and photoluminescence over spectral regions from the visible to the near infrared. The utility of such colloidal nanocrystals is demonstrated in photodetectors with responsivities up to 1 A/W, and humidity sensors operating over a dynamic range of 7 orders of magnitude and ~0.1s response. Both devices are fabricated by paint brushing or drop casting of these nanocrystals on paper substrates and outperform devices prepared from the same starting materials by vacuum deposition by several orders of magnitude. Properties can be further contolled through the use of biofunctional ligands such as riboflavin, flavin mononucleotide, and phosphonic acids. We demonstrate dedicated functionality leading to selective bioresponse. Importantly, these crystals are found to exhibit excellent operational stability in both air and various aqueous ionic environments. The semiconducting nanocrystals described here offer a cheap and nontoxic alternative to inorganic nanocrystals, as well as a new paradigm for obtaining organic semiconductor materials from low-cost and nontoxic commercial colorants.

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Authors : Marco Truccato, Angelo Agostino, Lorenzo Mino, Elisa Borfecchia, Eleonora Cara, Alessandro Pagliero, Lise Pascale, Lorenza Operti, Emanuele Enrico, Natascia De Leo, Matteo Fretto, Gema Martinez-Criado, Carlo Lamberti
Affiliations : Marco Truccato, Eleonora Cara, Alessandro Pagliero, Department of Physics, Interdepartmental Centre NIS, University of Torino, via Giuria 1, I-10125 Torino, Italy; Angelo Agostino, Lorenzo Mino, Elisa Borfecchia, Lise Pascale, Lorenza Operti, Department of Chemistry, University of Torino, via Giuria 7, I-10125 Torino, Italy; Emanuele Enrico, Natascia De Leo, Matteo Fretto, INRIM, National Institute of Metrological Research, Strada delle Cacce 91, I-10135 Torino, Italy; Gema Martinez-Criado,Experiments Division, European Synchrotron Radiation Facility, 6, rue Jules Horowitz, B.P. 220, F-38043 Grenoble Cedex, France; Carlo Lamberti, Southern Federal University, Zorge Street 5, 344090 Rostov-on-Don, Russia

Resume : We report on the fabrication of a proof-of-concept device by means of a novel direct-writing, X-ray nanolithography approach, which represents a natural extension of our recent studies on the influence of synchrotron radiation on the oxygen content of the Bi2Sr2CaCu2O8+δ (Bi-2212) superconducting oxide [1]. Selected areas of Bi-2212 microcrystals have been exposed to a 17.7 keV beam with a spot size of about 57x45 nm2 and a flux of 1-5x1011 ph/s. The irradiated regions have resulted in trenches able to force the current along the c-axis, therefore patterning a stack of intrinsic Josephson junctions. Indeed, the I-V curves clearly show the typical Josephson pattern, confirming that the delivered radiation dose was enough to locally turn the material into a non-superconducting state. Morphological analysis shows that no material has been removed from the trenched regions, but some local volume expansion can be observed. X-ray nanodiffraction frames collected at the irradiated areas show the presence of Bi-2212 peaks along with a Bi2O3 polycrystalline phase that does not appear in the non-irradiated regions. Our results represent a novel patterning method that in principle could be extended to several oxide materials. Possible advantages of this method can be represented by improved mechanical stability, absence of chemical contamination and of vacuum/oxide interfaces, and in potential higher steepness of the patterned structures. [1] A.Pagliero et al. Nano Lett. 2014, 14, 1583

Authors : R. Puzniak1, V. Markovich2, I. Fita1, A. Wisniewski1
Affiliations : 1Institute of Physics, Polish Academy of Sciences, Aleja Lotnikow 32/46, 02-668 Warsaw, Poland, 2Department of Physics, Ben-Gurion University of the Negev, 84105 Beer-Sheva, Israel

Resume : Charge-ordered (CO) state and antiferromagnetism are very stable in bulk samples of half-doped and electron-doped perovskite manganites but they become significantly suppressed and accompanied by an enhanced ferromagnetism upon reduction of the grain size. Magnetic studies of nanoparticles (NPs) with reduced grain size are exciting since properties of the particle core differ significantly from those of the shell and core-shell interaction leads to unexpected effects. With decreasing particle size from 60 to 15 nm for Sm0.43Ca0.57MnO3 and from 80 to 20 nm for Sm0.27Ca0.73MnO3, the relative volume of the ferromagnetic (FM) phase increases monotonously, while the CO phase progressively weakens and disappears completely in Sm0.43Ca0.57MnO3 NPs of average 15 nm particle size. Field cooled magnetization hysteresis loops of Sm0.1Ca0.9MnO3 NPs exhibit horizontal and vertical shifts, relatively small in 60 nm and much larger in 25 nm particles, due to size-dependent exchange bias effect. The exchange bias field and the coercive field depend in a non-monotonic way on cooling magnetic field. We have ascribed the magnetic behavior of the nanoparticles to a core-shell scenario with phase separated core containing FM clusters embedded in an antiferromagnetic (AFM) matrix and partially disordered AFM or paramagnetic shell. The suppression of the FM phase in the core with decreasing particle size may account for the enhancement of the exchange bias effect seen in smaller particles.

Authors : I. Fina1, J. Clarkson2, C. Frontera3, K. Cordero1, S. Wizotsky4, F. Sanchez3, X. Marti5, G. Catalan1, J. Fontcuberta3, R. Ramesh2,6
Affiliations : 1 ICN2-Institut Català de Nanociència i Nanotecnologia, Campus Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain. 2 Department of Materials Science and Engineering and Department of Physics, University of California, 94720 Berkeley, California, USA 3 Institut de Ciència de Materials de Barcelona, ICMAB-CSIC, Campus UAB, Bellaterra E-08193, Spain 4 Max Planck Institute of Microstructure Physics, Weinberg 2, Halle D-06120, Germany 5 Institute of Physics ASCR, v.v.i., Cukrovarnicka 10, 162 53 Praha 6, Czech Republic 6 Materials Science Division, Lawrence Berkeley National Laboratory, 94720 Berkeley,

Resume : Data encryption is the cornerstone of today's trust in the telecommunications arena. At present, complex algorithms are implemented in adjacent integrated circuits, which translate between actual and garbled information. Beyond requiring dedicated circuitry, this paradigm allows replicating the translating machine / algorithms. In this present, we present a magnetic media which spontaneously encrypts its contents at a mixed-phase boundary between ferromagnetic and antiferromagnetic phases. We show how data retrieval and editing is performed at the ferromagnetic phase, following the inspiration by Heat-Assisted Magnetic Memories, which are already coping its own niche in the non-volatile memory shelf. A detailed study allows us to conclude that the presence of coexisting phases at room temperature is an essential requirement for the observed memory effects. The ample availability of materials with mixed-phase phenomena close to room temperature anticipates that the findings reported here are not, by any theoretical perspective, limited to the specific material employed here, namely FeRh.

Authors : Agnieszka Jamroz, Lukasz Gladczuk, Jacek A. Majewski
Affiliations : Faculty of Physics, University of Warsaw, ul. L. Pasteura 5, 02-093 Warszawa, Poland

Resume : Group IV elements (C, Si, Ge, Sn), their binary alloys, and the alloys doped with group III and V elements can be stabilized in the form of honeycomb two-dimensional lattices. We employ first principles calculations in the framework of the density functional theory augmented by Monte Carlo calculations (within NVT ensemble and with valence force field Tersoff like potentials) to study the cohesive and electronic properties of ordered and disordered binary alloys of the whole plethora of the honeycomb monoatomic systems consisting of group IV atoms. For the ordered alloys, we determine phase diagrams, morphology of the structures leading to local total energy minima and possibility of transitions between structures under the external stress. For disordered AxB1-x alloys with x up to 50%, we determine the equilibrium structure and quantify the degree of the short- and long-range order in the alloys with the Warren-Cowley and Brag-Williams parameters, respectively. The ordered Si-C, Ge-C, and Sn-C alloys acquire highly energetically preferable low buckled equilibrium phase and have fairly large energy gap (roughly 2 eV). The disordered alloys with carbon are not random but exhibit rather large degree of short-range order. Further, we perform comparative study of the n and p-type doped systems on the basis of graphene and silicene, i.e., BC, NC, BNC, AlSi, PSi, AlPSi, to find out that these structures exhibit typically large degree of the short order.

Authors : Zurab Guguchia
Affiliations : Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institut

Resume : In this talk the results of the interplay between magnetism and superconductivity, obtained for the cuprate system La2-xBaxCuO4 (x = 1/8) and for the binary helimagnet CrAs, will be presented. Magnetism and superconductivity was studied in the static stripe phase of LBCO-1/8 by means of magnetization and muon-spin rotation (µSR) experiments as a function of pressure up to p = 2.2 GPa [1]. With increasing pressure the spin order temperature and the size of the ordered moment are not changing significantly. However, application of hydrostatic pressure leads to a remarkable decrease of the magnetic volume fraction Vm(0). Simultaneously, an increase of the SC volume fraction Vsc(0) occurs. Furthermore, it was found that Vm(0) and Vsc(0) at all p are linearly correlated: Vm(0) + Vsc(0) = 1. This is an important new result, indicating that the magnetic fraction in the sample is directly converted to the SC fraction with increasing pressure. The present results provide evidence that static stripe order and bulk superconductivity occur in mutually exclusive spatial regions. This conclusion is also supported by our recent oxygen isotope effect experiments in LBCO-1/8 [2]. Another interesting issue we studied with µSR is the suppression of magnetism and the occurrence of superconductivity in CrAs as a function of pressure [3]. The magnetism remains bulk up to p ≃ 3.5 kbar while its volume fraction gradually decreases with increasing pressure until it vanishes at p ≃ 7 kbar. At 3.5 kbar superconductivity abruptly appears with its maximum Tc ≃ 1.2 K which decreases upon increasing the pressure. In the intermediate pressure region (3.5 ≤ p ≤ 7 kbar) the superconducting and the magnetic volume fractions are spatially phase separated and compete for phase volume. A scaling of the superfluid density with Tc3.2 as well as the phase separation between magnetism and superconductivity point to a conventional mechanism of the Cooper-pairing in CrAs. [1] Z. Guguchia et al., New Journal of Physics 15, 093005 (2013). [2] Z. Guguchia et al., Phys. Rev. Lett. 113, 057002 (2014). [3] R. Khasanov, Z. Guguchia et. al., arXiv:1502.07573v1 (2015).

Authors : Alexandros Lappas (1), Andrej Zorko (2), Denis Arcon (2)
Affiliations : (1) Institute of Electronic Structure and Laser, Foundation for Research and Technology - Hellas, Vassilika Vouton, 71110 Heraklion, Greece; (2) Jozef Stefan Institute, Jamova c. 39, 1000 Ljubljana, Slovenia

Resume : Competition in chemically homogeneous strongly correlated transition-metal oxides leads to electronic-phase inhomogeneities on the nanoscale and amongst others to fascinating magnetoresisitve and superconducting states. In this respect, the frustrated spatially-anisotropic triangular-lattice antiferromagnet NaMnO2 is challenging as it features unexpected coexistence of long- and short- range magnetic correlations below TN = 45 K. Our complementary high-resolution synchrotron XRD, local-probe 23Na NMR and muon-spin relaxation (μ+SR) studies, corroborate that the layered NaMnO2 adopts a remarkable magnetostructurally inhomogeneous ground state in the absence of active charge degrees of freedom [1]. We show that two major opposing effects (elastic vs. magnetic exchange) of similar magnitude, lead to nearly equivalent, competing structural phases, which enable infinitesimal quenched disorder to locally lift the inherent frustration of the parent monoclinic phase. To provide an insight to this puzzling phase separation we have extended our study to the isomorphous CuMnO2 (TN = 65 K) compound, where local probes suggest that the interlayer cation (Cu) mediates the transition to a less inhomogeneous ground state [2]. NaMnO2 provides a paradigm of a rarely observed nanoscale inhomogeneity in an insulating spin system, an intriguing complexity of competition due to geometrical frustration. [1] A. Zorko et al., Nat. Commun. 5, 3222 (2014) [2] A. Zorko et al., Sci. Rep. 5, 9272 (2015)

Authors : Tomasz Story
Affiliations : Institute of Physics PAS, Warsaw, Poland

Resume : Electron crystal - phonon glass concept of modern thermoelectrics was technologically and experimentally verified in semiconductor bulk two-phase crystalline nanocomposites (Pb,Cd)Te-CdTe and in multilayer quantum-dot PbTe-CdTe nanostructures. Very low mutual solubility of lattice-matched rock-salt PbTe and zinc-blende CdTe crystals makes this system a model thermoelectric nanocomposite of zinc-blende CdTe nano-dots epitaxially embedded in a rock-salt PbTe thermoelectric crystalline matrix. We observed these nano structures forming spontaneously in properly annealed bulk crystals as well as developed the technological procedure of growing the PbTe-CdTe multilayer quantum-dot nanostructures by molecular beam epitaxy method controlling the size (from 5 to 30 nm) and distribution of CdTe dots. The n-type PbTe-CdTe multilayer with the smallest CdTe dots revealed at room temperature an increase of thermoelectric power as compared to reference bulk n-PbTe crystals. In PbTe-CdTe bulk nanostructures doped with Bi or Na we found an increased thermoelectric power and a reduced thermal conductivity resulting in very good ZT thermoelectric figure of merit parameter up to 0.9 at T=700 K for both n- and p-type materials. M. Szot et al., Functional Materials Lett. 7, 1440007 (2014). Work supported by the European Regional Development Fund through the Innovative Economy grant (POIG.01.01.02-00-108/09).


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Symposium organizers
Michael MAASAdvanced Ceramics | University of Bremen

Am Biologischen Garten 2, IW3 Rm 2140 28359 Bremen Germany

Hugues GIRARD French Atomic Energy Commission | CEA LIST

91191 Gif sur Yvette France

Bernd WICKLEIN Materials Science Institute of Madrid

Sor Juana Inés de la Cruz, 3 Madrid Spain

+34-91-3349000 ext.126
André R. STUDART ETH Zurich

Vladmir-Prelog-Weg 5, HCI G539 Zurich Switzerland

+41 44 633 7050