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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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Colloidal assembly of functional nanomaterials: from assembly routes to functional devices Part i : Michael Maas
Authors : S. Christoph, T. Coradin, F.M. Fernandes
Affiliations : Laboratoire de Chimie de la Matière Condensée de Paris, Sorbonne Universités, Université Pierre et Marie Curie, CNRS, Collège de France

Resume : Encapsulating viable cells in a foreign extracellular matrix or host is a conceptual challenge that has captivated a vast community of researchers. In addition, the physical entrapment of viable cells in hybrid materials is a promising way to enhance the productivity of cell-based bioprocesses, which renders the domain of potential economic interest. Hybrid materials display a remarkable potential for such a role due to their synthetic flexibility as well as the mild synthetic conditions required. In this presentation we disclose a new approach that couples freeze casting processing techniques with cell cryopreservation in order to obtain viable cells encapsulated in macroporous materials. The macroporous cellularized foams are subsequently silicified to obtain foam-like bionanocomposites. Results from the encapsulation of yeast cells (Saccharomyces cerevisiae) and bacteria (Pseudomonas aeruginosa) in polysaccharide-based foams using freeze casting will be discussed. Finally, the metabolic activity of the encapsulated species will be correlated to the silicification processes (molecular vs. colloidal) and to the thermodynamics of polysaccharide solution freezing. In conclusion, the applicability of the resulting cell-containing hybrid constructs will be discussed in terms of the potential environmental and biomedical applications.

Authors : Sylvain Deville
Affiliations : LSFC, UMR380 Cavaillon, France

Resume : The basic principle of ice-templating is the assembly of a second phase, usually particles, triggered by their progressive concentration increase in the inter-crystal space. This self-assembly can be extended to model systems of monodispersed or anisotropic particles, providing new insights in the self-assembly mechanisms involved. Particles exhibiting a shape factor will tend to align, provided that certain kinetic conditions are encountered. Examples include bundles of nanowires, platelets, and polymer fibers. Such experimental results can also be compared with the output of simple molecular dynamics models. Moving beyond spherical, isotropic particles, freezing can also be used to induce ordering of anisotropic particles. More complex behaviors can be observed using building blocks exhibiting self-assembly behavior, such as amphiphiles, opening the exploration of self-assembly under different thermodynamic conditions. These results open a new domain for the exploration of the self-assembly of amphiphiles molecules or similar self- assembly systems, in addition to providing increasingly elaborate architectures with improved functional properties.

Authors : R. Sriharitha, K. Böhlen, P. Hoffmann
Affiliations : Swiss Federal Laboratories for Materials Science and Technology-Empa, Thun, 3602, Switzerland

Resume : Surface microstructuring can be immensely important in the fields of tribology; wetting; photovoltaics; biology etc. to tune friction coefficient, abrasion resistance; to regulate water/liquid flow, to increase light trapping efficiency, for differential cell growth respectively. We will show the combination of large area excimer laser ablation of polymers and slip casting of ultrafine alumina powders to obtain mesoporous microstructured alumina samples. Laser ablated polycarbonate master molds can be fabricated with a large variety of 3D micro-features including free forms on areas up to 3 m2. Few shapes that have been tested are Switzerland map shape, Siemens star structures, pillars, diffractive optical elements, bone pit structures etc. One can precisely tune the grain and pore morphology by appropriately choosing the initial particle morphology and sintering parameters. The open porosity of microstructured mesoporous alumina samples can be filled with second phase material to fabricate high performance functional ceramics. Further examples of micro-features such as micro bowls or tear drops along with mesopores were produced that can serve as dual scale reservoirs for lubrication in tribology. We have also produced hierarchical roughness that can be tuned with appropriate surface chemistry of second phase to produce superhydrophobic composite. A drying model has been proposed to explain the various water flux transport mechanisms to dry the ceramic suspension. The model predicts that the drying time is independent of microstructured area and is linearly proportional to height of the ceramic slurry. The above predictions have been validated experimentally for different microstructured areas to produce bulk samples up to 10 mm thickness. The developed technology is robust, economical, easily up-scalable and much cleaner than literary used methods such as: direct diamond tool machining or laser ablation of ceramics and can be used for wider range of materials that can be slip cast.

Authors : L. Sciortino*, F. Messina, G. Buscarino, M. Cannas, F.M. Gelardi.
Affiliations : Dipartimento di Fisica e Chimica - Università degli studi di Palermo Via Archirafi, 36 - 90136 Palermo (Italy)

Resume : Carbon nanodots (CDs) are state-of-the-art, biocompatible and highly fluorescent nanomaterials, first reported in 2004, whose constituent elements are only carbon, oxygen, hydrogen and nitrogen. Due to their optical properties carbon-based nanomaterials are an excellent building blocks for the assembly of functional nanomaterials. Because the presence of nitrogen enhances the fluorescence quantum yield of CDs, we synthesize N-doped CDs by microwave decomposition of urea and citric acid. Thus we obtain highly fluorescent nanoparticles under both UV and VIS excitations. Most CDs sensors exploit the efficient quenching of the fluorescent intensity induced by the presence of metallic cations such as Cu2+, Fe3+, and Hg2+. Recently, this intensity-based sensing scheme has been improved by introducing so-called ratiometric fluorescent nanosensors, based on the fact that some CDs show two distinguishable emission signals. In this work we embedded CDs with typical diameter of 3 nm in a porous silica matrix, so obtaining a monolith that constitutes a sensing device exploiting the excellent luminescent properties of CDs. Our results are proof-of-principle devices where the introduction of metal ions (Cu2+, Ag+) changes the ratio between the two fluorescent bands. On these grounds we propose a solid-state ratiometric sensor based on luminescent CDs.

10:30 Coffee break    
Colloidal assembly of functional nanomaterials: from assembly routes to functional devices Part ii : Bernd Wicklein
Authors : Jan P. F. Lagerwall
Affiliations : University of Luxembourg Physics & Materials Science Research Unit

Resume : The liquid crystal self-assembly of water-suspended cellulose nanocrystals (CNCs) into a helical arrangement was observed already more than 20 years ago [1] and the phenomenon was used to produce iridescent solid films by evaporating the solvent or via sol-gel processing [2]. Yet it remains challenging to produce optically uniform films and to control the pitch reproducibly, reflecting an unsatisfactory understanding of the ordering process. We recently proposed that the short pitch of the solid films is a result of a collapse of a helical structure with much longer pitch, formed in the equilibrium liquid crystalline CNC suspension and arrested into a jammed state at an early stage of solvent evaporation [3]. Moreover, by drying suspensions that are initially fully liquid crystalline, rather than isotropic or in the phase coexistence regime, we achieved solid films where the helix axis was oriented vertically throughout the sample [4], as opposed to the mosaic texture with randomly varying helix orientation commonly observed when drying low-concentration CNC suspensions. In this presentation I will summarize these findings and report on our recent advances in the quest to precisely control the helix pitch and orientation in CNC films. [1] J.F. Revol et al., Int J Biol Macromol, 14, 170 (1992) [2] J.A. Kelly et al., Acc Chem Res, 47, 1088 (2014) [3] J.P.F. Lagerwall et al., NPG Asia Mater, 6, e80 (2014) [4] J.H. Park et al., ChemPhysChem, 15, 1477 (2014)

Authors : Christina Schütz1,2, Michael Agthe1, Andreas B. Fall1, Korneliya Gordeyeva1, Valentina Guccini1,2, Michaela Salajková3, Tomás S. Plivelic4, Jan P. F. Lagerwall5, German Salazar-Alvarez1,2, Lennart Bergström1
Affiliations : 1 Department of Materials and Environmental Chemistry, Stockholm University, 106 91 Stockholm, Sweden 2 Wallenberg Wood Science Center, KTH, 100 44 Stockholm Sweden 3 Department of Biosciences, University of Oslo, 0371, Oslo, Norway 4 MAX IV Laboratory, Lund University, PO Box 118, 221 00 Lund, Sweden 5Physics and Materials Science Research Unit, University of Luxembourg, 1511, Luxembourg

Resume : The increasing need to replace fossil fuels as a source of energy and raw material is resulting in extensive research efforts towards identifying and developing high performance materials and devices based on renewable sources. Cellulose, the most versatile and abundant biopolymer in nature, is one of the obvious choices. Due to its properties arising from its hierarchical structure, cellulose has been used for millennia by mankind although it is currently used, in the form of microfibers, mainly in the paper and pulp industry. However, many efforts are being directed towards retrieving even smaller cellulose constituents such as nanofibers and nanocrystals (i.e., nanocellulose), which can actually be used in high performance materials.1 In order to do so, a better understanding of the behavior and interactions of these novel nanomaterials are required. Particularly, it has been found that similar to the chitin crystals found in marine organisms such as the American lobster2 cellulose nanocrystals also form a chiral nematic phase.3 In this work the packing of CNC in the anisotropic chiral nematic phase has been investigated by small angle X-ray scattering and laser diffraction. The separation distance between neighboring CNCs and the pitch of the chiral nematic phase have been determined over the entire isotropic-anisotropic biphasic region, from the onset of the anisotropic phase formation into the high concentration range above 6 vol% where the dispersion is fully liquid crystalline. We show that the twist angle between neighboring CNCs increases from about 1 ° up to 4 ° as the CNC volume fraction increases. The volume fraction dependence of the twisting was related to the increase in the magnitude of the repulsive interactions between the charged rods as the average separation distance decreases. This information can further utilized for optical, mechanical or sensing applications by controlling the helical or non-helical alignment of CNCs. 1. R. J. Moon, A. Martini, J. Nairn, J. Simonsen, and J. Youngblood, Chem. Soc. Rev., 2011, 40, 3941–94. 2. A. Al-Sawalmih, C. Li, S. Siegel, H. Fabritius, S. Yi, D. Raabe, P. Fratzl, and O. Paris, Adv. Funct. Mater., 2008, 18, 3307–3314. 3. J. P. F. Lagerwall, C. Schütz, M. Salajkova, J. Noh, J. Hyun Park, G. Scalia, and L. Bergström, NPG Asia Mater., 2014, 6, e80.

Authors : Wei Cheng, Felix Rechberger, Markus Niederberger
Affiliations : Laboratory for Multifunctional Materials, Department of Materials, ETH Zurich, Vladimir-Prelog-Weg 5, 8093 Zurich (Switzerland)

Resume : In the research area of two dimensional (2D) nanomaterials, it remains a great challenge to synthesize 2D nanostructured metal oxides and assemble them into three dimensional (3D) macroscopic aerogels. In this work, we developed a facile solution route for synthesis of Y2O3 nanosheets with thickness of 1.5 nm, width about 40 nm. These 2D nanosheets can be gelled into 3D networks by a simple centrifugation-induced gelation method. The resultant 3D wet gel can be converted to aerogel via supercritical drying with CO2. The as-prepared Y2O3 aerogel has a high surface area of 445 m2/g and a very low density of 0.15 g/cm3 which is only 3% of the bulk density of Y2O3. Importantly, the aerogel can survive a high temperature annealing. After annealing at 600 °C, the integrity and porous structures of the gel body remain good. The surface area can still reach a high value of 214 m2/g. This observation indicates that the Y2O3 aerogels could be good candidates for catalyst support. Moreover, we are capable of doping and co-doping Y2O3 nanosheets with Eu3+ and Tb3+. With these doped Y2O3 nanosheets, we are able to fabricate 3D aerogels which are highly luminescent under UV excitation, covering emission spectra ranging from red to green. These extremely light 3D luminescent networks with highly porous structures may have potential applications in optoelectronic devices. Finally, we manage to in-situ deposit metal nanoparticles into the 3D hydrogel which can be converted to 3D Y2O3 nanosheet aerogel@metal nanoparticles composites. The composite aerogel may have promising application in catalysis of some specific gas reactions such as oxidation of CO or reduction of NOx.

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.

12:15 Lunch break    
Colloidal assembly of functional nanomaterials: from assembly routes to functional devices Part ii : Hugues Girard
Authors : Siming Yu, Anna Laromaine, Anna Roig,
Affiliations : Nanoparticles and Nanocomposites Group (, Institut de Ciència de Materials de Barcelona, Consejo Superior de Investigaciones Científicas (ICMAB-CSIC), Campus de la UAB, Bellaterra, Catalunya, E-08193 Spain.

Resume : The combination of magnetic and optical properties in a nanomaterial offers enormous potential in bio-sensing, imaging and therapeutical applications. Simple approaches to synthesize hybrid magneto-plasmonic nanoparticles with anisotropic plasmonic shapes avoiding cytotoxic reactants are in high demand. Microwave heating is an attractive non-conventional energy source for chemical synthesis due to the high acceleration and yield of the performed reactions. In comparison to other conventional heating methods, microwave radiation avoids temperature gradients decreasing occurrences of asynchronic nucleation and heterogeneous nanocrystal growth. In addition, microwaves heats polar substances rapidly and intensely promoting selective heat at desired sites. Thus, complex multi –material heterostructures can be fabricated. I will report on a facile, fast and bio-friendly microwave-assisted polyol route to synthesize gold nanotriangles decorated by a monolayer of iron oxide nanoparticles. The hybrid nanoparticles are readily dispersable in water, superparamagnetic at room temperature and display local surface plasmon resonance in the near infrared region. In addition, these hybrid nanostructures can self-assemble as a monolayer at the liquid-air interface. The effect of the reaction conditions and the magnetic and plasmonic properties of the nanoconstructs will be presented.

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 : Katharina Wiemer1, Huan Peng2, Andrij Pich2, Ulrich Simon1
Affiliations : 1Institute of Inorganic Chemistry, RWTH Aachen University and JARA-Soft Matter Science, Landoltweg 1, 52074 Aachen, Germany; 2Leibniz Institute for Interactive Materials DWI and Institute for Technical and Macromolecular Chemistry, RWTH Aachen University, Forckenbeckstraße 50, 52056 Aachen, Germany

Resume : Combining different functional nanostructures such as thermo-responsive microgels (MG) and inorganic nanoparticles (NP) exhibiting size dependent physical properties may lead to novel multifunctional hybrid nanostructures. We report the synthesis of new hybrid nanostructures consisting of thermo-responsive MG and gold nanoparticles (AuNP), which are bound to each other reversibly via thermo-labile DNA linkers. The MG consist of poly(N-vinylcaprolactam-co-N-(methacryloxy)succinimide (PVS) and were synthesized via a dispersion polymerization process. Single stranded, NH2-terminated DNA (ssDNA) was covalently connected to the MG via succinimide groups, resulting in PVS-MG with controlled amounts of incorporated ssDNA. Thereby the thermo-responsiveness of MG is retained, expressed by an unaffected volume phase transition (VPT). AuNP capped with complementary ssDNA ligand have been bound to the DNA functionalized PVS-MG by Watson-Crick base pairing, which can thermally be dehybridized. These hybrid nanostructures have been characterized via UV-Vis spectroscopy, dynamic light scattering, zeta potential measurements and transmission electron microscopy and were found to be colloidally stable. Due to the optical absorbance of the AuNP the hybrid nanostructures are addressable by light and heat as external stimuli, so that the VPT as well as the assembly/disassembly of MG and AuNPs due to dehybridization of the complementary DNA strands can be triggered by two independent means.

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.

15:30 Coffee break    
Colloidal assembly of functional nanomaterials: from assembly routes to functional devices Part iv : Bernd Wicklein
Authors : Joachim Bill
Affiliations : University of Stuttgart, Institute for Materials Science, Heisenbergstr. 3, 70569 Stuttgart, Germany

Resume : Living nature provides impressive evolution-optimized processes, which lead to complex-structured inorganic solids. These solids are formed by genetically determined biomineralization processes at ambient conditions. During these processes biopolymeric templates control the mineralization and thus the structure formation of the inorganic components. Molecular bionics aims at the transfer of biomineralization principles to the generation of inorganic functional materials. Accordingly, within this contribution the generation and structuring of inorganic functional materials (i. e. oxides of elements, like Zn or V, which are not produced by natural biomineralization) by the colloidal assembly of inorganic nanoparticles is treated. The assembly processes are triggered by bioorganic templates. Examples for the architectural design of the materials based on the structural features of biominerals will be given. Moreover, approaches for the in vivo synthesis of inorganic functional materials by unicellular organisms are presented. In addition, the mechanical and the electrical properties of the obtained materials as well as their integration into devices are discussed.

Authors : Matthew A. Hood, Andre Scheffel, Damien Faivre
Affiliations : Max Planck Institute for Colloids and Interfaces, Max Planck Institute for Molecular Plant Physiology

Resume : Inspiration for modern materials can be intimately tied to our observations of nature. Biological formation of minerals is regulated by organic macromolecules, which aids in selection of mineral polymorphs, as well as controlling crystal morphology, and introducing composite mechanical properties to the biogenic crystals. The minerals interact with the macromolecules and crystallize by well-controlled mesocrystalline processes or through amorphous precursors. Many marine creatures use calcium carbonate as a structural mineral in the formation of shells including coccolithophores, a single cell marine algae that forms coccoliths, which are ring- or shield-like structures composed of numerous atypical morphologies of calcite crystals ~100 nm in size, and has great importance for the ocean’s carbon sequestration cycle. We used high resolution X-ray diffraction and X-ray absorption techniques in order study the assembly of CaCO3 coccolith crystals and their ultrastructure.

Authors : Davide Carnelli1, Rafael Libanori1, Nuria Rothfuchs1, Marco Binelli1, Luc Nicoleau2, Bernhard Feichtenschlager2, Gerhard Albrecht2, and Andre' R. Studart1
Affiliations : 1 Joint Research Network on Advanced Materials and Systems (JONAS) - program of ETH Zurich and BASF SE, Complex Materials, Department of Materials, ETH Zurich, 8093 Zurich, Switzerland. 2 BASF Construction Materials & System Research, Dr. Albert Franks Str 32, D-83308 Trostberg, Germany.

Resume : Enhancing the stress transfer between matrix and reinforcing elements is a general problem in structural composites. In cement-based systems, for example, while cheap and effective solutions are available at the macro scale by artificially roughened steel bars, the modification of the surface topography of micron-sized reinforcing elements to improve its interfacial interaction with the matrix still represents a challenging task. In this work, such problem has been tackled by developing an approach to design the reinforcing elements that is inspired by the surface topography of the aragonite platelets in nacre. These platelets show surface asperities that lead to mechanical interlocking and frictional resistance when they slide across each other in the fracture process. The proposed solution consists in the modification of the surface of micron-sized platelets by roughening them with nanometer size spheres, which would act as asperities on the surface of the larger particles and promote energy dissipation during an applied mechanical deformation. Cement- and polymer-based composites containing these modified platelets showed improved flexural modulus, strength, strain energy absorption and fracture toughness with respect to the bare platelets. This study demonstrates that a better anchoring of the reinforcing element with the matrix was established thanks to the surface roughening, which ultimately leads to a better reinforcing effect compared to unmodified platelets.

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 : Kulakovich O.1, Trotsiuk L.L.2, Shabunya-Klyachkovskaya E.1, Matsukovich A.1, Vaschenko S.2
Affiliations : 1- National Academy of Sciences of Belarus, B.I. Stepanov Institute of Physics, Nezavisimosti Avenue 68, 220072 Minsk, Belarus; 2-Belarusian State University, The Chemical Department, Nezavisimosti Avenue 4, 220030 Minsk, Belarus

Resume : Nowadays the synthesis and characterization of metal nanoparticles with variable size and shape arouse growing interest due to their geometry-dependent unique optical, electronic, and catalytic properties. Rod-shaped gold nanoparticles are of significant interest in nanoplasmonics because of their tunable longitudinal plasmon bands and the “lightning rod” effect on surface electromagnetic enhancement. In this report, the standard synthesis of gold nanorods (NRs) according seed-growth technique has been modified. The size and aspect ratio of rods were changing by varying of two parameters: the Au seed solution volume as well as of the ascorbic acid ratio to gold salt in the growth solution. Electrostatic layer-by-layer deposition of Au nanorods atop the polyelectrolyte film has been produced the extremely stable plasmonic film. As a result, three types of gold NR films with the different rod aspect ratio (3.1-4.2) have been considered as the active substrates for Surface Enhanced Raman Scattering (SERS). To reduce the «metal-analyte» distance a surfactant CTAB bilayer on the NRs surface have been substituted with L-cysteine. The L-cysteine modified NRs provide a huge enhancement for inorganic malachite microcrystal while the non-modified NRs provide it for molecular analytes such as malachite green and mitoxantrone. These effects could be explained with the classical theory of electromagnetic and chemical mechanism of SERS.

Authors : Varun Sreenivasan1, 2, W. A. Wan Razali1, 2, Mark Connor3, Andrei Zvyagin1, 2, 4, Ewa Goldys1, 2
Affiliations : 1Department of Physics and Astronomy, Macquarie University, Sydney, NSW, Australia 2ARC Centre of Excellence for Nanoscale BioPhotonics, Australia 3Department of Biomedical Sciences, Macquarie University, Sydney, NSW, Australia 4N. I. Lobachevsky State University of Nizhny Novgorod, Nizhny Novgorod, Russia

Resume : Ultrasensitive optical micro imaging has become a standard technique in life sciences, especially for elucidating dynamics of single biomolecules in a cellular context. The technique allows visualization of complex biological interactions, such as ligand binding, vesicle transport and cytoskeletal re-organization. These applications rely on photoluminescent probes, and place stringent demands on the probe characteristics such as brightness, photostability and biocompatibility. Recent advances in engineering photoluminescence probes have been focused on improving their detection sensitivity, photostability, associated biological toxicity, surface chemistry and production. While the newer probes such as quantum dots and upconversion nanoparticles have overcome many limitations of conventional molecular dyes, they are still far from perfect. Our research focuses on the development of novel photoluminescent nanomaterials, particularly tailored for targeting and biomolecular imaging within cells, tissues and small-animal models. We report on the development, large-scale production, surface engineering and biological imaging of a novel photoluminescent nanoparticle probe based on the gemstone ruby, termed Nanoruby. Nanorubies, which are Cr3+-doped Al2O3 nanoparticles in the alpha crystallographic phase, were identified by our group [1] as a probe uniquely suited for ultrasensitive detection and imaging, by virtue of their photostability, spectrally narrow emission and long emission lifetime. Similar to bulk ruby, nanorubies exhibit strong photoluminescence emission at two sharp spectral lines at 692.9 and 694.3 nm, with two broad excitation peaks at ~400 nm and ~532 nm. This property, in combination with their long (~4 ms) photoluminescence lifetime, allows multiplexed imaging in the presence of other dyes with single-particle detection sensitivity. Extreme photostability, owing to the well-isolated Cr3+ centers within the Al2O3 crystal matrix, imply resilience to environmental conditions and suitability for long duration single particle tracking in native tissues. We present two methods of nanoruby production, followed by its characterisation, surface modification, cell labeling and sensitive optical microscopy. Nanorubies were synthesized in a top-down fashion by using either laser ablation or high energy ball-milling. The two methods resulted in nanorubies in the size range of 5-40 nm and 20-200 nm, respectively, whose size distribution can be improved and tuned by adjusting ball milling parameters. While laser ablation resulted in spherical particles in alpha or gamma (non-ruby) phase, the ball milling method yielded large (gram) quantities of nanorubies in random crystallographic structures. The photoluminescence, crystal structure, morphology and surface chemistry of the nanorubies were thoroughly characterized by microscopy, spectroscopy, x-ray diffraction, electron microscopy, energy dispersive x-ray spectroscopy and infrared spectroscopy. The particles were amenable to functionalisation of amine, carboxyl and PEG groups using established silane based chemistry. However, owing to considerable non-specific adsorption of biomolecules onto to the nanoruby surface, a silica shell was introduced to improve biological labeling performance. The silica coating allowed more reliable functionalisation strategies and reduced non-specific binding, making the nanorubies suitable of specific labeling of cells and tissues. Single nanoruby imaging sensitivity of the developed time gated microscopy was confirmed by correlative imaging with atomic force microscopy and intensity distribution mapping with transmission electron microscopy. Single particles of size ~30 nm were visualized at a diffraction limited resolution, over an area of 100 m x 100 m with ~1 s imaging time. The developed nanoruby particles enabled cellular labelling, and detection at single particle level in an optically crowded environment created by autofluorescence, nuclear dye, quantum dot and/or a hyperpolarization-sensitive dye. These results open up the possibility of ultrafast, simultaneous, single-particle sensitive imaging of multiple cell-signaling events, such as those that follow drug-activation of cellular receptors. [1] A M Edmonds, M A Sobhan, V K A Sreenivasan, et. al., Particle and Particle Systems Characterization, Vol. 30, pp. 506, 2013

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 : Je-Seung Yoo, Young-Soo Seo
Affiliations : Department of Nano Science & Technology, Sejong University, 98 Gunja, Gwangjin, Seoul143-747, Rep. of Korea

Resume : Graphene oxide (GO)-Fe3O4 nanoparticle complex has recently attracted an attention in various fields such as MRI, battery, and removal of heavy metal from waste water. For the complex formation, Fe3O4 nanoparticle was used to be chemically-modified to generate phi-phi interactions or covalent bonding to GO or synthesized on GO by a precipitation method. Compared to those methods, we developed a simple and cost-effective method assisted by ultrasound where hydrophobic nanoparticle forms hydrophobic bonding to hydrophobic part on graphene oxide. Chemical structure of the complex was confirmed by UV-vis spectrometer, FTIR, and Raman scattering, and its morphology was monitored by TEM, SEM, and XRD. Stability of the complex structure was confirmed by multiple precipitation-dissolution cycles and repetitive heavy metal ion adsorption tests using a voltammetry where the ion-adsorbed complex was easily removed by a magnet.

Authors : Peter Nadrah, Andrijana Sever Škapin
Affiliations : Slovenian National Building and Civil Engineering Institute, Dimičeva ulica 12, SI-1000 Ljubljana, Slovenia

Resume : Photocatalytically active materials are useful for degradation of organic materials, producing mineralized products such as H2O and CO2. But sometimes their potent efficiency needs to be tuned down and adjusted towards only certain type of organics. Selectivity in degradation is desirable when only certain types of organics need to be degraded or when some intermediate products is preferred over mineralized products. Examples of these situations include degradation of pollutants on the walls while keeping pigments and binders intact and removal of hazardous organics in water purification while retaining naturally occurring macromolecules. We synthesized a selectively photocatalytically active material by wrapping TiO2 in mesoporous silica shell. Narrow pores (~3 nm) in silica shell prevent degradation of macromolecules such as starch, while as the same time allow degradation of model pollutants, such as rhodamine B and fluorescein. Furthermore, silica shell also influenced the degradation kinetics of these dyes. While similar in size, they differ in cationic/anionic groups. Given the low isoelectric point of silica, the cationic dye exhibits a stronger adsorption than the anionic dye. This difference gives rise to a faster degradation of the cationic dye compared to the anionic dye in silica-coated TiO2. This effect was not observed in uncoated TiO2. The results are promising for the development of future photocatalytically active coatings and water purification systems.

Authors : Tepanov A.A., Makarik A.Yu., Kudrinskiy A.A., Lisichkin G.V.
Affiliations : Lomonosov Moscow State University Department of Chemistry Division of petroleum chemistry and organic catalysis Laboratory of Surface Chemistry 119991Russia, Moscow, Leninskiye Gory, 1, bld. 3

Resume : A micromechanical sensor is the equipment for chemical analysis which measures mechanical deflections induced by chemical processes on the surface of the cantilever. Although cantilever-based chemical sensors have low detection limits and high sensitivity, the further development of techniques for improvement of its sensitivity is of great importance. We suggest that creation of regular nanoscale roughness on the receptor layer will contribute the enhancement of interactions between molecules on the cantilever surface There are different methods to achieve nanoscale roughness. In our work, we used citrate-stabilized silver nanoparticles to create rough receptor layer of micromechanical sensor. For that, Si-surface of cantilever was modified with SH-groups by reaction with 3-mercaptopropyltrimethoxysilane (3-MPTMS). Ag NPs were deposited onto SH-groups from aqueous sol. To evaluate sensitivity of the as-prepared sensor, the oligonucleotide 5`-HS-T (CH2CH2O) 6GTGACGTAGGTTGGTGTGGTTGGGGCGTCAC-3` (5`-HS-T ... C-3`) with terminal SH-group was chosen as a model analyte. It was found that deflection of cantilever with Ag NPs-based receptor layer in the oligonucleotide solution is higher, at least, in 103 times in comparison with cantilever without nanoparticles. Sensitivity enhancement caused by both increase of surface area of the sensitive layer and electrostatic interactions of nanoparticles leading to higher deformation of the cantilever.

Authors : Korneliya S. Gordeyeva, Andreas Fall, Lennart Bergström
Affiliations : Department of Materials and Environmental Chemistry Stockholm University

Resume : Thermal insulating foams should be light, mechanically strong, fire retardant, and preferably produced from abundant and renewable raw materials. Cellulose as a polymeric material exhibits low thermal conductivity and high heat capacity, making it suitable for insulating applications. In this work we will demonstrate how composite foams of TEMPO-mediated cellulose nanofibrils (CNF) and a non-ionic surfactant can be produced. The foamability, bubble size and stability of the foam will be evaluated as a function of composition and foaming conditions. The evolution of the air bubble size with time at different temperatures (23 and 60C) will be also presented. We have developed a bio-mimetic cross-linking methods based on a delayed acidification of a calcium carbonate dispersions that not only improves the mechanical strength but also aids in preserving the shape during drying. The dry foams have been studied by SEM and X-ray tomography and we will discuss how the pore size distribution is affected by the drying conditions and the cross-linking. The effect of addition of clays such as sepiolite and montmorillonite on the mechanical and fire retardant properties will be discussed.

Authors : C. Leostean, O. Pana, M. L. Soran, M. Stefan, S. Gutoiu, S. Macavei
Affiliations : National Institute for Research and Development of Isotopic and Molecular Technologies, 67-103 Donat st., 400293 Cluj-Napoca, Romania

Resume : The idea of having a magnetic material with adjustable properties it’s a challenge which can be fulfilled by using composite nanomaterials. For these multi-component nanosystems, due to the generation of an increased number of nano interfaces, one obtains a better control of properties as compared to conventional nanoparticles. This work shows selected results regarding the control of magnetic interparticle interactions through the type of covering materials and the measurement environment. Single magnetic phase or multiple coupled magnetic phase systems of nanoparticles were analyzed. As single phase magnetic nanoparticles, Fe3O4 and Fe@Au systems are presented while, Fe@FePt(L10) illustrate multiphase magnetic behavior. From the analysis of AC temperature dependence of the susceptibility one obtains the characteristic relaxation time of the nanoparticles. Information concerning weak interparticle interactions can be determined by using Arrhenius or Vogel–Fulcher approach. The magnetic behavior of these systems was correlated with the preparation conditions as well as with structural and compositional sample analysis. Thus, magnetic properties can be better controlled for targeted application especially in medicine and biology as well as in information storage devices.

Authors : Anna Maria Ferretti1, Elena Capetti1, Claudio Evangelisti1, Sara Mondini1, Alessandro Ponti1, Ermelinda Falletta2, Cristina della Pina2
Affiliations : 1. Nanotechnology Lab. ISTM ? CNR, via G. Fantoli 16/15-20138 Milano It; 2. Universit? degli Studi di Milano and ISTM ? CNR, via C.Golgi 19-20133 Milano Italy

Resume : An extensive effort has been spent to develop shielding materials able to reduce the electromagnetic interference (EMI). In order to tailor and achieve specific EM properties within a single material we studied the combination of poly(aniline) (PANI) with magnetic nanoparticles (MNPs) developing an innovative green method for the synthesis of PANI/Fe3O4 nanocomposites, which are obtained by oxidative polymerization of N-4-aminophenylaniline using magnetic Fe3O4 MNPs as both catalyst and filler. We prepared MNPs of different sizes using (i) a solvothermal protocol for MNP27 (dmedian=27 nm) and MNP10 (dmedian=10 nm) and (ii) Metal Vapour Synthesis (MVS) for the smaller MNP2 (dmedian=2.3nm). The PANI/Fe3O4 nanocomposites were characterized as to their structure (XRD, FTIR, UV-Vis), morphology (TEM, STEM), composition (AAS, EELS, EDX) and magnetic properties (SQUID). We evaluated the MNP size effect on the polymerization: the most catalytically active MNPs are the smallest ones (d = 2.3 nm). We proved that PANI/Fe3O4 nanocomposites possess a number of interesting features: the MNPs do not undergo chemical or crystallographic change under the used polymerization conditions; the MNPs are almost uniformly dispersed in the polymer matrix guaranteeing a good homogeneity of the nanocomposite; the PANI/Fe3O4 nanocomposites have tunable magnetic properties as a function of the MNPs size. Financial support by Fondazione Cariplo (Milano, Italy) under grant n. 2012-0872 is acknowledged.

Authors : Joao Paulo Coelho,[a] Guillermo González-Rubio,[a] Annette Delices,[a] José Osío Barcina,[b] Cástor Salgado,[b] David Ávila,[c] Ovidio Peña-Rodríguez,[d] Gloria Tardajos,[a] and Andrés Guerrero-Martínez*[a]
Affiliations : [a] Departamento de Química-Física, Universidad Complutense de Madrid, Spain; [b] Departamento de Química Orgánica I Universidad Complutense de Madrid, Spain; [c] Departamento de Química Inorgánica Universidad Complutense de Madrid, Spain; [d] Instituto de Fusión Nuclear Universidad Politécnica de Madrid, Madrid, Spain.

Resume : The method of self-assembly has emerged as a natural starting point for the bottom-up fabrication of nanostructures with precise organization. Particularly, the self-assembly of gold nanoparticles (AuNPs) have gained an increasing of attention in nanotechnology applications due their unique optical responses through the excitation of localized surface plasmon resonances (LSPRs). The relatively easily modifiable surface of AuNPs by thiol-functionalized molecules makes them useful to control their surface chemistry, rendering them ideal building blocks for nanoarchitecture design. However, the control of supramolecular self-assembly to produce large and reversible arrays with defined geometrical arrangements of the nanoparticles remains a difficult task. Herein, we synthetized a novel thiol functionalized nonionic surfactant (IgeSH) for coating spherical AuNPs (IgeS-AuNPs). Once the IgeS-AuNPs solution showed a great stability in aqueous solution, α-cyclodextrin (α-CD) molecules were used to forming inclusion complexes, as hosts trapped onto linear organic molecule, forming polyrotaxanes on the nanoparticles surface. Although no self-assembly has been observed in solution, a spontaneous formation of self-assembled layers with hexagonal close packing of nanoparticles has been obtained by simple drop casting under controlled drying conditions. Additionally, the deposit samples could be fully redispersed in water, showing a reversible character of the noncovalent interactions between polyrotaxanes at the surface of the nanocrystals. The reversibility of the crystallization process paves the way for designing excellent reusable materials to prepare plasmonic sensors with added the potential to be recovered by cycles of redispersion, washing, and centrifugation. In this work, we report a combined X-ray powder diffraction, electron transmission microscopy, and UV-Vis study of the self-assembled and supramolecular polyrotaxane network formed between IgeS-AuNPs and α-CD.

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 : Masaki Ujihara, Chia-Chi Chang, Toyoko Imae
Affiliations : Graduate Institute of Applied Science and Technology, National Taiwan University of Science and Technology, Taiwan; Department of Chemical Engineering, National Taiwan University of Science and Technology, Taiwan

Resume : Non-spherical Au nanoparticles (AuNPs) have unique plasmonic behaviors. The confeito-like AuNPs are the non-spherical AuNPs with many bosses on their surfaces, and they could be synthesized by the reduction of tetrachloroaurate using H2O2 in an alkaline condition. The protecting agents in the reaction solutions determined the detailed structures of surfaces, and the plasmon absorption bands of the confeito-like AuNPs were changed by their sizes and the detailed surface structures. Then, the surface-enhancing effects of confeito-like AuNPs were studied on infrared absorption and Raman scattering. The surface-enhanced infrared absorption spectra of eicosanoic acid were measured using the transmission method, and the confeito-like AuNPs indicated the strong surface-enhanced Raman scattering in aqueous solutions of rhodamine 6G. The enhancing factor of surface-enhanced Raman scattering reached to 105. The enhancing rates of the bands and their concentration dependency in the spectra provided information about the conformations of adsorbate molecules and the processes of their layer formation. The adsorption behaviors of molecules on the confeito-like AuNPs will be discussed at the conference.

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 : J. Matousek, L.Splichalova, P. Capkova, J. Pavlik
Affiliations : University of J.E.Purkyne, Pasteurova 1, 40096, Usti nad Labem, Czech Republic

Resume : This work is focused on phyllosilicate materials, particularly montmorillonite belonging to the smectite group, and their potential plasma and chemical treatment. We focused on them due for their good availability and unique properties like a negative charge layer which enable them to bind cationic dyes as are rhodamine B and methylene blue, thus there is a chemical treatment after which the montmorillonite acquire a new property - fluorescence. The chemical treatment has been combined with the plasma treatment, enabling a dehydration of phyllosilicate structure and forming new active sites. The plasma treatment can replace previously used more demanding heat treatment having the same effect. Plasma treatments of montmorillonite were done in fluidized bed reactor with subsequent application of dyes from solutions of varying concentrations. Analyses of modified montmorillonite were performed, by FTIR, XPS, XRD and spectrofluorimetry confirming dehydration (change of d-spacing) and successful binding of dye on the montmorillonite.

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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Colloidal assembly of functional nanomaterials: from assembly routes to functional devices Part v : German Salazar-Alvarez
Authors : Erik Reimhult
Affiliations : Institute for Biologically inspired materials, Department of Nanobiotechnology, University of Natural Resources and Life Sciences, Vienna, Austria

Resume : New approaches have enabled synthesis of controlled core-shell architectures for superparamagnetic iron oxide nanoparticles, which make it possible to increase their colloidal stability and rationally vary their morphology. Such developments from our lab will be described and their application to study the assembly of nanoparticles at liquid-liquid interfaces. The intrinsic size range of these core-shell nanoparticles spanning from that of proteins to viruses, and their stability enabling their use as responsive and superparamagnetic material building blocks, make their assembly at interfaces interesting from both an applied and a fundamental point of view. Findings regarding the relationship between nanoparticle structure and the assembled membrane structure at liquid interfaces as well as techniques and tools to characterize these structures will be presented. In particular, the ability of such “soft” nanoparticles to bind strongly to liquid interfaces and reduce the total energy of the interface will be described. This property is also used to stabilize nano- and microscale oil droplets of direct relevance for encapsulation and magnetic manipulation of hydrophobic drugs and other chemicals in aqueous environments.

Authors : Tobias Bollhorst, Michael Maas, Kurosch Rezwan
Affiliations : Advanced Ceramics, University of Bremen, Germany

Resume : Colloidosomes[1] are microcapsules consisting of nanoparticle shells which can be self-assembled from a wide range of colloidal particles with selective chemical, physical, and morphological properties. The formation of colloidosomes can be interpreted as the growth of thin-films of nanoparticles at the fluid-fluid interface of water-in-oil-emulsion droplets. By introducing oil-soluble surfactants (lipids) into the emulsification system we were able to substantially decrease the size of the emulsion droplets. Furthermore, the lipids partially dissociate at the emulsion droplet interface and introduce a charge, which mitigates the electrostatic potential of the nanoparticles resulting in the formation of a rigid nanoparticle film at the emulsion droplet interface.[2] Our group recently established the formation of submicron colloidosomes with distinct functionality self-assembled from nanodiamonds,[3] and from fluorescent and superparamagnetic nanoparticles[4]. Currently, our research focuses on the integration of mesoporous silica coated superparamagnetic iron oxide nanocrystals into submicron colloidosomes which have great potential for the emerging field of nanomedicine and can be fine tuned for various applications. [1] A. Dinsmore, et al. Science 2002, 298, 1006p [2] T. Bollhorst, M. Maas, K. Rezwan, et al., Chem. Mater. 2013, 25, 3464p [3] M. Maas, T. Bollhorst, K. Rezwan, PPSC. 2014, 31, 1067p [4] T. Bollhorst, M. Maas, K. Rezwan, et al. Ang. Ch. Int. Ed. 2015, 54, 118p

Authors : O. Pana, M. L. Soran, S. Gutoiu, M. Stefan, C. Leostean, S. Macavei
Affiliations : National Institute for Research and Development of Isotopic and Molecular Technologies, 67-103 Donat st., 400293 Cluj-Napoca, Romania

Resume : Different types of magnetic nanoparticles composites can be designed as multifunctional platforms with controllable magnetic properties, thus being able to facilitate their use in different applications. Moreover, the interface interactions between different components can greatly improve the performance of the multi-components system and even generate new synergetic properties. Two types of half-metal magnetic nanoparticles (NP) like Fe3O4 and FePt (L10) alloy were coated with semiconductors like ZnS, TiO2 and poly(3 hexylthiophene) (P3HT). By ZnS coating of Fe3O4 NP the saturation magnetization significantly increases while by TiO2 coating a reversed process takes place. In case of FePt (L10) hard magnetic NP coated with P3HT 8 times significant reduction of the coercivity was also observed. We argue that these processes may be analyzed within the framework of interface charge/spin transfer associated to the work function equalization. Thus, due to the interface energy band alignment only electronic spin–down states are transfer from ZnS valence band into Fe3O4 polarized conduction band or from P3HT valence band into FePt (L10) leading, in both cases, to the polarization of semiconductor. In case of FePt (L10)/P3HT it leads to the decrease of the anisotropy field of FePt (L10) but only for the spin-down states. These make this type composite suitable for magnetic recording applications since it becomes accessible for the usual magnetic recording heads.

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

Authors : Derya Erdem, Nicholas Bingham, Laura J.Heyderman, Markus Niederberger
Affiliations : ETH Zurich, Paul Scherrer Institut

Resume : Current technology requires processing of nanoparticles into thin films for realization of devices with magneto-electric and magneto-optical functionalities as a result of miniaturization demand.1 In this work, we present liquid phase deposition of composite thin films using preformed nanoparticle dispersions as a flexible and generalized strategy to fabricate various nanoparticle-based systems. BaTiO3-CoFe2O4 and CoFe2O4-SiO2 nanoparticles are assembled into co-dispersed and multilayered composite thin films for magneto-electric devices and magneto-optical thin films respectively. Nanoparticle dispersions are fabricated via microwave assisted non-aqueous sol gel routes and Stoeber process and then further arranged into corresponding thin film geometries via sequential spin coating-drying steps followed by sintering. Structural characterizations on final films indicated full phase control during film deposition process owing to the predefined nature of nanoparticles. Electrical, magnetic and magneto-optical characterizations proved the emergence of desired functionalities such as ferroelectric switching, spontaneous magnetization, Kerr rotation and tunable refractive indices. 1.Kubli, M.; Luo, L.; Bilecka, I.; Niederberger, M., Microwave-assisted nonaqueous sol-gel deposition of different spinel ferrites and barium titanate perovskite thin films. Chimia 2010, 64, (3), 170-172

10:30 Coffee break    
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 : Meltem F. Aygüler, Michael D. Weber, Bianka M. D. Puscher, Dana D. Medina, Pablo Docampo, Rubén D. Costa
Affiliations : Department of Chemistry and Center for Nanoscience, University of Munich (LMU), Butenandtstr. 11, D-81377 Munich, Germany; Department of Chemistry & Pharmacy, University of Erlangen-Nuremberg (FAU), Egerlandstr. 3, D-91058 Erlangen, Germany

Resume : Light-emitting electrochemical cells (LECs) have recently emerged as a potential alternative to organic light-emitting diodes (OLEDs) due to the use of air-stable injection layers and/or electrodes, as well as its simple device architecture consisting of a single electroluminescent layer sandwiched between two electrodes. In LECs, the electroluminescent layer can be either a conjugated light-emitting polymer, an ionic transition-metal complex or inorganic II-VI quantum dots (QDs). However, the significant reduction of the photoluminescence quantum yields (PLQYs) of this type of QDs after ligand exchange makes hybrid perovskite nanoparticles (NPs), having PLQYs of over 80%, attractive for application in LECs. Here, we have synthesized NPs based on formamidinium lead bromide (FAPbBr3) and methylammonium lead bromide (MAPBr3). Importantly, we have demonstrated that the photophysical features can be easily tuned by exchanging the organic cation, achieving lower radiative bimolecular recombination rates for FAPbBr3 NPs. Additionally, we report for the first time LECs based on perovskite NPs by an easily up-scalable spray-coating technique. Stable luminance of 1-2 cd/m2 at low driving currents was achieved for both types of materials. Overall, this work opens a new avenue of research into the field of organic-inorganic metal halide nanoparticles bearing different alkyl ammonium groups and their application in the developing field of thin-film lighting devices.

Authors : Ievgenii Liashenko
Affiliations : Catalonia Institute for Energy Research (IREC)

Resume : Development in electronics is limited by capabilities of current manufacturing techniques. Direct-writing noncontact manufacturing techniques propose many advantages over traditionally used lithography, such as: relative simplicity, cost-effectiveness, high-speed production, minimization of material waste, and eco-friendliness, and allow usage of variety of substrates. Inkjet printing has only limited application in printing circuit boards, and not capable to manufacture 3D micro-devices. The concept of forcing inks through the orifice, inherent to inkjet printing, puts severe limitations to ink’s maximum viscosity and to minimum diameter of nozzle, making it increasingly hard to deposit droplets with diameter less than 30 µm. To address this challenge we develop 3D printing system based on electrohydrodynamic (EHD) effect, capable of jet-printing high-viscosity inks of virtually any nature. It drives the jet flow by applying voltage potential between needle and substrate, and generating so-called Taylor cone. This specialty of EHD approach permits to use highly viscous inks, and to generate high-aspect ratio patterns with the feature size down to 1 µm. This study comprises multidisciplinary approach to the development of functional conductive inks by manipulating its formulation: from nanoparticle synthesis to optimization of ink’s rheological and electrical properties for EHD printing; and aims to manufacture ultra-high resolution conductive patterns and 3D structures.

Authors : Ajay Singh a,b Lukas Lutz a, Gary Ong a, Simone Reoux c, Jean Jordon-Sweet c, Delia Milliron b.
Affiliations : a. The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, USA b. Department of Chemical Engineering, The University of Texas at Austin, Austin, TX , USA c. IBM Watson Research Center, 1101 Kitchawan Road, Yorktown Heights, New York 10598, USA

Resume : Earth abundant compound semiconductors are promising candidates for the fabrication of high-quality thin film solar cell absorber. In particular, these compound (I2-II-IV-VI4) semiconductor material possess high optical absorption coefficients (105 cm-1), high power conversion efficiencies, offer good photostability against long-term radiation, and cause less environmental problems due to their relatively low toxicity. However, device efficiencies for these materials are significantly lower than the best efficiencies achieved for chalcopyrite based solar cells. Low device efficiency for earth abundant semconductors have been attributed to difficulties in achieving large grained, single phase thin films with controlled stoichiometry using vacuum-based deposition or precursor annealing techniques. These techniques can also result in the unintentional formation of a large number of secondary phases in the Cu-Zn-Sn-S system that significantly reduces the device performance. Nanocrystal based methods for the fabrication of thin film photovoltaics are an attractive alternative to vacuum deposition processes due to their simplicity and cost effectiveness. Here, we develop a simple and reliable solution approach to process large grained, single phased kesterite Cu2ZnSnS4 films via thermal treatment of assembled nanocrystal-precursor films consisting of wurtzite Cu2ZnSnS4 nanorods. The crystal structure, composition and electrical properties of the final film were investigated with SEM, XRD, Ramna, PL and Hall effect measurements.

Authors : Simonetta Rima and Marco Lattuada
Affiliations : Adolphe Merkle Institute, University of Fribourg, Chemin des Verdiers 4, 1700 Fribourg, Switzerland

Resume : Since the term ‘nanocomposites’ has been proposed for the first time by Theng in 1970, the field has grown in a mature and highly developed branch of material science. Numerous procedures for the preparation of nanocomposite materials have been investigated in order to generate materials with controlled features, which is still one of the great challenges in nanotechnology. The purpose of this work is to use the extended and large knowledge of self-assembly behavior of spherical nanoparticles in aqueous dispersions and its dependence on interparticle interactions for the preparation of hybrid nanostructured composites. The nanocomposites have been obtained from mixed aqueous dispersions of soft poly(butyl acrylate/methyl methacrylate) copolymer particles (80 nm diameter) and filler particles. Two different filler particles have been utilized: hard silica nanoparticles (20 nm diameter), with various concentrations, and graphene oxide nanosheets. In order to investigate the specific role of the interparticle interactions on the final structure and mechanical properties of the materials, the nanocomposites have been synthetized following three different assembly strategies. The first strategy consists in mixing the two stable particle suspensions with same surface charge. The second strategy consists in inducing aggregation/gelation of the filler particles inside the matrix particle stable suspension. The third strategy consists of hetero-aggregation of particle suspensions with opposite surface charge. The different hetero particle suspensions have then been precipitated and subsequently annealed, giving rise to a nanostructured polymeric composite, which has been characterized in term of structure and mechanical properties using different techniques (SAXS, AFM, SEM, tensile test).The excellent dispersion of the filler particles in the polymer matrix achieved by this methods, the ability to control the microstructure of the composite material lead to excellent mechanical properties, which can be tuned by controlling the degree of association of the filler particles.

12:30 Coffee break    
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 : Shengqiang Zhou
Affiliations : Helmholtz-Zentrum Dresden-Rossendorf, Institute of Ion Beam Physics and Materials Research, Dresden, 01328, Germany

Resume : Combining semiconducting and ferromagnetic properties, ferromagnetic semiconductors have been under intensive investigation for more than two decades. Mn doped III-V compound semiconductors have been regarded as the prototype of ferromagnetic semiconductors from both experimental and theoretic investigations. The magnetic properties of III-V:Mn can be controlled by manipulating free carriers via electrical gating, as for controlling the electrical properties in conventional semiconductors. However, the preparation of ferromagnetic semiconductors presents a big challenge due to the low solubility of Mn in semiconductors. Ion implantation has been developed as a standard method for doping Si in microelectronic industry. In this talk, I will show how ion beams can be used in fabricating and understanding ferromagnetic semiconductors. First, ion implantation followed by pulsed laser melting (II-PLM) provides an alternative to the widely used low-temperature molecular beam epitaxy (LTMBE) approach [1-6]. Both ion implantation and pulsed-laser melting occur far enough from thermodynamic equilibrium conditions. Ion implantation introduces enough dopants and the subsequent laser pulse deposit energy in the near-surface region to drive a rapid liquid-phase epitaxial growth. Going beyond LT-MBE, II-PLM is successful to bring two new members, GaMnP and InMnP, into the family of III-V:Mn. Both GaMnP and InMnP films show the signature of ferromagnetic semiconductors and an insulating behavior. Second, we use helium ion to precisely compensate hole in ferromagnetic semiconductors while keeping the Mn concentration constant [7-9]. By this approach, one can tune the magnetic properties of ferromagnetic semiconductor as well as pattern a lateral structure. It also provides a route to understand how carrier-mediated ferromagnetism is influenced by localization. [1] M. Scarpula, et al. Phys. Rev. Lett. 95, 207204 (2005). [2] D. Bürger, S. Zhou, et al., Phys. Rev. B 81, 115202 (2010). [3] S. Zhou, et al., Appl. Phys. Express 5, 093007 (2012). [4] M. Khalid et al., Phys. Rev. B 89, 121301(R) (2014). [5] Y. Yuan, et al, IEEE Trans. Magn. 50, 2401304 (2014). [6] Y. Yuan, et al. J. Phys. D: Appl. Phys. in press (2015). [7] Lin Li, et al., J. Phys. D: Appl. Phys. 44 099501 (2011). [8] Lin Li, et al., Nucl. Instr. Meth. B, 269, 2469-2473 (2011). [9] S. Zhou, et al. Phys. Rev. B, in revision (2015).

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

15:30 Coffee break    
Colloidal assembly of functional nanomaterials: from assembly routes to functional devices Part vii : Ulrich Simon
Authors : A. Guerrero-Martínez
Affiliations : Departamento de Química Física I, Universidad Complutense de Madrid, Avda. Complutense s/n, 28040, Madrid, Spain

Resume : The optical properties of metal nanoparticles are dominated by the so-called surface plasmon resonance, which arises from coupling of the oscillating electric field of an electromagnetic radiation and conduction electrons. For a few noble metals (gold, silver, copper) such coupling takes place at visible frequencies, which provides colloidal dispersions of such nanoparticles with bright colors. The precise position of the plasmon absorption band depends not only on the nature of the metal, but also on other parameters such as particle size and shape or the dielectric properties of the environment. In this presentation, recent results will be presented on the self-assembly of gold nanoparticles (AuNPs) through the formation of 2D and 3D superlattices of AuNPs, with a tuning of the localized surface plasmon resonances. We will show herein that the self-assembly strategy of AuNPs can be controlled by using supramolecular interactions both in aqueous solution and organic solvents. The use of thiol-functionalized amphiphilic molecules and supramolecular nanocapsules to stabilize AuNPs induces the spontaneous formation of supramolecules, which provides large and homogenous supercrystals with close packing of nanoparticles. Once formed, the self-assembled supercrystals can be fully redispersed upon addition of solvent. Additionally, the temperature-controlled reversibility of the self-assembly process may offer excellent reusable materials.

Authors : Won Kook Choi, Dong-Ick Son,Hong Hee Kim, Do Kyeong Hwang
Affiliations : Korea institute of Science and Technology

Resume : Oxide semiconductor-nanocarbon(graphene, CNT, C60 hybrid quantum dots was synthesized by simple chemical reaction using Zn acetate and light acid treatment of nanocarbons. In ZnO-graphene quasi core-shell QDs, outer layer covered ZnO was disclosed as a single layer graphene by high resolution TEM. From time-resolved photoluminescence (TRPL) for ZnO-graphene, it was also revealed that life time of UV emission peak shortened from nsec to a few hundreds psec in time-resolved photoluminescence spectrum. The result can be strongly supported by quenching phenomenon of UV emission peak and can be well understood by the formation of charge-transfer exciton from ZnO to graphene. Based upon these hybrid QDs, ZnO-graphene QDs LED having with ITO/PEDOT:PSS/Poly-TPD/ZnO-graphene/Cs2CO3/Al) was firstly fabricatd and showed luminance slightly brighter than 1,000 cd/m2. Moreover, a large area planar lighting devices of 5x5 cm2 with 10 x10 matrix on glass and PET was successfully fabricated and operated. Moreover, after dissolving ZnO-graphene by HCl and filtering, graphene quantum dots (GQDs) with high purity could be obtained and showed green emission PL independent of excitation-wavelength. In a similar way, ZnO-nano carbons (C60, CNT) hybrid quantum dots were also synthesized. Their application for UV photovoltaics and highly photoelectrochemical efficiency for water splitting will be discussed.

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 : M. A. Roldan1,2, M. P. Oxley3, Q. A. Li4, H. Zheng4, K. E. Gray4, J. F. Mitchell4, S. J. Pennycook5, and M. Varela2,1
Affiliations : 1Dpto. Física Aplicada III, Universidad Complutense de Madrid 28040 Madrid (Spain) 2Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (USA) 3Dpt. Physics and Astronomy, Vanderbilt University, Nashville, TN 37212 (USA). 4Argonne National Laboratory, Argonne, IL, 60439, (USA). 5Dept. of Materials Science & Engineering, National University of Singapore, Singapore 117575.

Resume : The properties of complex oxides are extremely sensitive to minor changes in doping. For example, in manganites it is still not clear whether chemical order (or disorder) is in any way connected to phenomena such as double exchange, electronic phase separation or charge ordering. By means of aberration corrected scanning transmission electron microscopy and electron energy-loss spectroscopy combined with simulations we have carried out an atomic resolution study of the colossal magnetoresistant manganite La2-2xSr1+2xMn2O7 (LSMO) [1-3]. We have compared three different compositions within the complex phase diagram of LSMO [1,2]: a ferromagnetic metallic material (x=0.36), an insulating, antiferromagnetic charge ordered (AF-CO) compound (x=0.5), which also exhibits orbital ordering, and an additional AF sample (x=0.56). We find a significant degree of long-range chemical ordering in all cases, which increases in the AF-CO range. However, the degree of ordering is never complete. Our results show that chemical ordering over distinct crystallographic sites is not needed for electronic ordering phenomena to appear in manganites, and other explanations, including electronic degrees of freedom, play a determining role when trying to explain the complex electronic behavior of LSMO. [1] LI Q. et al. (2007). Phys. Rev. Lett. 98, 167201 (1-4). [2] MITCHELL J.F. et al. (2001). J. Phys. Chem. B 105, 10731-11052. [3] ROLDAN M. A. et al. (2014) Microscopy & Microanalysis 20, 1791-1797.

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 : A. Abbassi, A. El Moussaoui, H. Ez-Zahraouy, A. Benyoussef,
Affiliations : Laboratory of Magnetism and High Energy Physics (URAC 12) B.P. 1014, Faculty of Sciences, Mohammed V University, Rabat, Morocco.

Resume : Electronic and Optical properties of BiMO3 with M = Zinc, Vanadium, Manganese, Cobalt, and Fe were studied by first principles calculations using the density functional theory (DFT). We investigated optical reflectivity, optical absorption, band structure, and Total / Partial density of state using the full potential-linearized augmented plane wave (FP-LAPW) method with the generalized gradient approximation (GGA) and modified beak Johnson approximation(mBJ), implemented in the Wien2k package. With the mBJ approximation the gap appears for BiCoO3 and BiFeO3 ,it is equal to 1.7ev and 2.6ev respectively , which is in good agreement with experimental results. While BiMO3 (M=Zn,V,Mn) presents a metallic behavior. We investigated that the optical absorption and the reflectivity is stable in visible light for the case of BiCoO3 and BiFeO3.This study predict also that he reflectivity and the optical absorption of BiMO3/M=Mn,V,Zn is high in Ultraviolet region. The appearance of a significant magnetic moment for the case of Fe and Co with considerable gap is an excellent result that can be exploited in different optoelectronic and magneto-optic applications

10:30 Coffee break    
Authors : Hiroshi Katayama-Yoshida, Tetsuya Fukushima, Kazunori Sato, Hidetoshi Kizaki
Affiliations : Graduate School of Engineering Science, Osaka University; Graduate School of Engineering Science, Osaka University; Graduate School of Engineering, Osaka University; Graduate School of Engineering, Osaka University

Resume : Based on the spinodal nano-decomposition (SND) of dilute magnetic semiconductors (DMS) [1, 2], we generalized the SND to the application of catalysis [3-5] and photovoltaics [6, 7], where nano-scale particle formation in catalysis and and nano-scale separation of electrons and holes are essential in order to enhance the efficiency. First, we summarize the shape control (Konbu-Phase & Dairiseki-Phase) and dimensionality dependence of crystal growth condition on SND in DMS [1, 2]. Second, we discuss the application of SND for the formation of nano-particles and the self-regeneration in three-way catalysis for automotive emission control by perovskite La(Fe,Pd or Rh)O3 based on the multi-scale simulations [3-5]. Third, we propose (i)self-regeneration mechanism [6] and (ii)self-organized nano-structures [7] by SND in chalcopyrite Cu(In,Ga)Se2, kesterite Cu2ZnSnSe4, and perovskite CsSnI3 for the low-cost, environment-friendly and high-efficiency photovoltaic solar cells using first-principles calculations and multi-scale simulations. [1] K. Sato et al., Rev. of Mod. Phys., 82, 1633 (2010). [2] T. Dietl et al., preprint 2015. [3] H. Kizaki et al., Applied Physics Express 1 (2008) 104001. [4] H. Kizaki et al., Chem. Phys. Lett. 579, 85 (2013). [5] I. Hamada et al., J. Am. Chem. Soc. 133, 18506 (2011). [6] S. B. Zhang et al., Phys. Rev. B 57, 9642 (1998). [7] Y. Tani et al., Applied Physics Express, 3, 101201 (2010); Jpn. J. Appl. Phys., 51 050202 (20129.

Authors : R. Lorenzi, A. Azarbod, L. De Trizio, E.S. Ignat'eva, V.N. Sigaev, N.V. Golubev, A. Paleari
Affiliations : R. Lorenzi; A. Azarbod; A. Paleari Department of Materials Science, University of Milano-Bicocca, via Cozzi 55, 20125 Milano, Italy A. Azarbod: Department of Physics, University of Ferrara, via Saragat 1, 44100 Ferrara, Italy L. De Trizio: Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy E.S. Ignat'eva; V.N. Sigaev; N.V. Golubev P.D. Sarkisov International Laboratory of Glass-based Functional Materials, Mendeleev University of Chemical Technology of Russia, Miusskaya Square 9, 125047 Moscow, Russia

Resume : Optical glassceramics are an important class of functional materials mainly employed in photonic and optoelectronic applications, as well as for advanced fiber optics. Here we present recent results on phase separation processes and optical properties of alkali germanosilicate glasses containing gallium oxide nanoparticles. Samples, with typical composition 7.5Li2O–2.5Na2O–20Ga2O3–35GeO2–35SiO2 (mol%), are obtained from the melt-quenching method. The resulting glasses are completely amorphous, but show phase separation, on the nanometer scale, deriving from liquid–liquid phase separation in the melt. Nanocrystallization of gallium oxide, in its metastable gamma phase, is thermally activated inside the matrix at about 615 °C. Treatment at higher temperature causes the formation of LiGa5O8 polymorph by Li ion diffusion from the surrounding matrix to the nanocrystals. In a second step, a further increment of temperature induces an order-to-disorder LiGa5O8 change that finally dissociates causing the formation of beta-Ga2O3. Neutron scattering, X-ray diffraction analysis, differential scanning calorimetry, and transmission electron microscopy studies have been performed so as to assess nucleation and crystal growth mechanisms. Parallel to morphological studies, we also present optical response of these systems, characterized by a strong UV-excited blue luminescence due to intrinsic defects and its dependence on thermal treatments.

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 : Chris Palmstrøm
Affiliations : Electrical & Computer Eng. and Materials, University of California, Santa Barbara, CA 93106, USA

Resume : Epitaxial rare earth monopnictide (RE-V) nanostructures embedded within a III-V semiconductor matrix are of great interest due to a number of exciting electrical and magnetic properties, including phonon scattering for high ZT thermoelectrics and sub-picosecond carrier lifetimes for terahertz devices. Most work on this nanocomposite system has focused on embedded RE-V nanoparticles, e.g. ErAs or ErSb nanoparticles embedded in GaAs (001) and GaSb (001). This presentation will focus on the growth of highly anisotropic Er-group-V (Sb and As) nanostructures embedded in a III-V semiconductor matrix by self-assembly during molecular beam epitaxial growth of ErxIII1-x-V by codeposition. In-situ scanning tunneling microscopy in combination with molecular beam epitaxy allows for atomic scale characterization during different stages of growth. For growth of GaSb(001) with increasing Er concentration, ErSb embedded nanostructures change from nanoparticles to vertical nanorods, nanotrees, horizontal nanorods and nanosheets. The resulting ErxGa1-xSb nanocomposites are single crystalline with a continuous Sb-sublattice. The vertical nanorods are continuous throughout the ErxGa1-xSb layer, their axes are parallel to the [001] growth direction, and they self-assemble into ordered arrays aligned along the [-110] direction. In the case of GaAs, ErAs nanorods can also form by self-assembly during molecular beam epitaxial growth of ErxGa1-xAs by codeposition. In this case the nanorod formation with the rods growing in the <211> direction was found for growth on GaAs (h11)A surfaces. In contrast, ErAs nanorods do not form on GaAs (h11)B or GaAs (001) surfaces. Scanning tunneling spectroscopy and angle resolved photoemission spectroscopy were used to measure the electronic bandstructure of embedded RE-V nanostructures of varying dimensions, namely 0D nanoparticles, 1D nanorods, and 2D thin films. In this presentation, the growth mechanisms for ErxGa1-xSb and ErxGa1-xAs that result in embedded nanorod formation will be presented. The atomic scale growth mechanisms are a result of surface diffusion and wetting characteristics which are used to explain the differences for the self-assembly of nanostructures for ErxGa1-xSb and ErxGa1-xAs.

12:30 Lunch break    
Authors : Stephen J. Blundell
Affiliations : Oxford University Department of Physics

Resume : Molecular groups can now be intercalated into iron-based superconductors with dramatic consequences on the superconducting properties. These species act as charge reservoirs, sources of electrical polarization, and also make subtle structural modifications to superconducting layers, all of which can make novel adjustments to the band structure that in turn can control superconducting properties. By synthesizing the compound Lix(NH2)y(NH3)1−yFe2Se2 (x ~ 0.6; y ~ 0.2), in which lithium ions, lithium amide and ammonia (NH3) act as the spacer layer between FeSe layers, we have turned a 9 K superconductor into a 43 K superconductor [1]. Further chemical modification allow us to produce a range of new superconducting materials which we have studied using a variety of techniques including muon-spin rotation [2]. Recently, we have used hydrothermal reactions to produce layered lithium iron selenide hydroxides with chemical formula Li1–xFex(OH)Fe1–ySe and thereby producing compounds whose transition temperature can be tuned from zero up to about 40 K [3]. Future prospects for new superconducting materials using these novel synthetic routes will be discussed, as will also our current understanding of the superconductivity in these materials. (Work performed in collaboration with S. J. Clarke and coworkers at Oxford, RAL and Durham, UK.) [1] M. Burrard-Lucas et al., Nature Materials 12, 15 (2013). [2] F. R. Foronda et al. in preparation. [3] H. Sun et al., Inorg. Chem. 54, 1958 (2015).

Authors : S. K. Chen, Edmund H. H. Lim, Josephine Y. C. Liew, M. M. Awang Kechik, S. A. Halim
Affiliations : Physics Department, Faculty of Science, Universiti Putra Malaysia, 43400, Serdang UPM, Selangor, Malaysia

Resume : In this work, Se and S doped FeTe polycrystalline samples were prepared by solid state reaction method at ambient pressure without resort to vacuum condition. In order to minimize oxidation, argon gas flow was maintained throughout the heat treatment. Based on the powder x-ray diffraction data, both Se and S doped FeTe samples were indexed to tetragonal structure with space group of P4/nmm. The lattice parameters a- and c-axis shrink significantly with the substitution of Se and S. As shown by the scanning electron microscope (SEM) images, doping with Se and S led to the development of plate-like grain structure. Temperature dependence of magnetic moment measurements showed the onset of superconducting transition temperature, Tc at 13.5 K when Te is replaced with 50 at.% of Se. For S doped FeTe, diamagnetism was detected but no bulk superconductivity was measured up to 30 at% substitution for Te. All the samples exhibit ferromagnetic behavior as shown by the field dependent magnetization measured at room temperature.

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)

15:30 Coffee break    
Authors : Yaniv Gelbstein
Affiliations : Department of Materials Engineering, Ben-Gurion University, Beer-Sheva, Israel.

Resume : In the recent years, many efforts were made for generation of nano features in bulk thermoelectric materials for enhancement of the thermoelectric figure merit via the reduction of the lattice thermal conductivity. Taking into account that thermoelectric direct converters from heat to electricity, without involving of any moving parts, exhibit a major stability advantage for long-term operation, compared to many other competing conversion methods, the stability of nano-featured bulk thermoelectric materials is a major issue for consideration. Such converters usually operate under high temperatures and large temperature gradients conditions, which can affect the stability of the nano-features embedded in the bulk thermoelectric main phases. As an example, one popular production method of nano-featured bulk materials is based on rapid consolidation (e.g. Spark Plasma Sintering) of nano powders obtained by melt spinning or energetic ball milling. Yet, grain coarsening effects can result in gradual deterioration of the nano-structures and thermoelectric performance degradation upon long-term high temperatures operation. In the current research, an alternative, thermodynamic nano-features generation approach in bulk IV-VI based thermoelectric materials, was considered, using controlled phase separation conditions according to the relevant phase diagrams.

Authors : M. Boukhari 1, A. Barski 1, P. Bayle-Guillemaud 1, P.-H. Jouneau1, E. Bellet-Amarlic1, E. Hadji 1, V. Favre-Nicolin 1, Y. Liu 2, E. Prestat 3, S. Haigh 3, D. Taïnoff 2 and O. Bourgeois 2
Affiliations : 1 Univ. Grenoble Alpes, CEA, INAC-SP2M, F-38000 Grenoble, France 2Institut Néel, CNRS, UPR 2940, 38052 Grenoble, France 3 School of Materials, University of Manchester, Manchester, United Kingdom

Resume : Thermoelectric materials have recently attracted great interests. Among them, nanostructured materials are very promising because they can exhibit the properties of a “phonon glass electron crystal” material. In our presentation, we will show that nanostructured GeMn is one of the best candidates for thermoelectric applications. Molecular Beam Epitaxy (MBE) growth of GeMn layers under particular growth conditions leads to the formation of Ge3Mn5 nanoclusters embedded in a perfectly crystallized germanium matrix. Beside the thermoelectric properties of this nanostructured GeMn, the structural properties of Ge3Mn5 nano-inclusions have been also investigated using HRSTEM and XRD. The chemical composition has been studied using STEM-EELS and STEM-EDX techniques. Thermal conductivity measurements by 3-omega technique show that the thermal conductivity of nanostructured GeMn is 20 times lower than in the bulk Ge crystal. Doping level of this nanostructured GeMn can be tuned by ion implantation in order to achieve both N-type and P-type doping. This approach opens a way to the fabrication of (Ge,Mn) based thermoelectric devices.

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).

Authors : Sh. Zangeneh1*, M. Ketabchi2
Affiliations : Materials Department, Razi University, Kermanshah, Iran Mining and Metallurgical Engineering Department, Amirkabir University of Technology, Tehran, Iran

Resume : The precipitation of nanoscale M23C6 carbides in Co28Cr5Mo0.3C implant alloy during tungsten inert gas (TIG) welding has been systematically investigated. The nanoscale M23C6 carbides precipitated at hcp-fcc interfaces and based on HR-TEM observations was in the range of 10-100 nm. In addition, X-ray diffraction analysis showed that higher amount of athermal ε-martensitic (≈ 2-fold those found in the solution-treated sample) was achieved after welding process. Apparently, the nanoscale M23C6 carbides formation was strongly promoted by development of athermal martensite transformation. Furthermore, these particles bring a very high hardness around 850 HVN to the alloy. In general, the present investigation is intended to give a comprehensive understanding of nanoscale M23C6 carbides precipitation in Co28Cr5Mo0.3C alloy subjected to tungsten inert gas (TIG) welding process. In particular, we observed that the nanoscale M23C6 carbides distributed in interdendritic regions and were promoted by development of athermal ε-martensite phase.

18:00 Best Student Presentation Awards Ceremony and Reception (Main Hall)    

No abstract for this day

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