Symposium : C
Size-dependent properties of nanomaterials
| start at | Subject | Num. |
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| Size Effects I : Eric Mittemeijer | ||
| 09:00 | Size effect on the mechanical behaviour of advanced structural steels from usual to nano-scale microstructures Authors : O. Bouaziz ArcelorMittal Research, Voie Romaine-BP30320, 57283 Maizières-lès-Metz Cedex, France Centre des Matériaux, Ecole des Mines de Paris, CNRS UMR 7633, B.P. 87, 91003 Evry Cedex, France Affiliations : Resume : In order to achieve strengths higher than 1500MPa in single phase steels, the developed metallurgical solutions are the martensitic grades or more recently austenitic steels Fe-Mn-C with TWining Induced Plasticity (TWIP). An alternative suitable strategy is based on a very strong grain size refinement in the sub-micron domain where even strengths in excess of 2000MPa are possible in the single phase iron based system. The overview of these developments has been a unique opportunity to propose and to validate microstructural based modelling for the mechanical behaviour in a large range of length scales.
For instance, for nanocrystalline metals, while strength can be significantly increased by reducing the grain size, a disadvantage is a low strain-hardening capability. Despite the successes of MD modelling in identifying the elementary mechanisms of plasticity of nanocrystals, it is not always easy in such simulations to extract the underlying physical processes. This is the reason why a more transparent physical based approach has been proposed and assessed.
Finally, by exploiting the observed thermal stability of the high density of twins induced by plastic straining in a Fe-Mn-C TWIP steel, an excellent combination of yield stress and work-hardening rate can be achieved by prestrain and recovery treatment. The balance between the complexity of the metallurgical route and the obtained mechanical properties is very promising for bulk nanostructured single phase steels. The mechanisms are discussed in relation with the involved microstructural length scales. | CA 1 |
| 09:30 | Size Effect Study on Magneto Electric Properties of Nano Nibi2O4 Synthesized Through Sol-Gel Auto Combustion Technique Authors : T. Prabhakaran and J. Hemalatha* Advanced Materials Lab, Department of Physics, National Institute Of Technology, Tiruchirappalli, Tamilnadu, India - 620 015. *hemalatha@nitt.edu Affiliations : Resume : Highly crystalline single phase magneto electric NiBi2O4 nano particles have been synthesized by using sol-gel auto combustion technique. The structural, thermal, morphological, optical, ferro electric and magnetic studies have been carried out. XRD patterns reveal the formation of highly crystalline nano NiBi2O4 with high degree of phase purity. FTIR spectra also prove the formation of pure nano NiBi2O4. The coexistence of ferroelectric and ferromagnetic orderings in the sample has been confirmed. The temperature and fuel effects are found to have strong influence on size, structural, ferroelectric and magnetic properties of materials. The effect of nano size on the ferroelectric and ferromagnetic properties has been studied and reported. The magnetic measurements show that the nano NiBi2O4 samples exhibit strong ferromagnetism. The ferroelectric hysteresis and ferromagnetic hysteresis behaviors are discussed as the functions of particle size and are correlated. | CA 2 |
| 09:45 | SUBSTRATE EFFECT ON THE SIZE DEPENDENCE OF THE MELTING TEMPERATURE OF SUPPORTED GOLD NANOCLUSTERS Authors : P.V. Borisyuk, V.D. Borman, M.A. Pushkin, V.N. Tronin, V.I. Troyan National Research Nuclear University “MEPhI”, 31 Kashirskoe chausse, 115409 Moscow, Russia Affiliations : Resume : The experimental results for the low-energy electron scattering from Au nanoclusters pulsed laser deposited on highly oriented pyrolytic graphite HOPG(0001) and amorphous SiO2 substrates are presented. The intensity of the elastic peak electron spectrum evidences a gradual decrease in the differential cross-section for the electron scattering from nanoclusters with decrease of their size. It can be explained by an increase in the root mean square deviation of Au atoms in a cluster (Debye-Waller factor) and an increase in the roughness of Au cluster surface (structural factor). The Lindemann criterion allows the estimation of clusters melting temperature decreasing with their size. HRTEM and STM images of Au clusters on SiO2 and HOPG evidence that clusters keep their solid state for sizes d>1.5 nm for Au on SiO2 and d>2.0 nm for Au on HOPG. The difference in Tm(d) can be explained by the role of the rough boundary and non-compact shape of Au clusters on HOPG as compared to the smooth semispherical shape of Au clusters on SiO2 surface. Given the same pulsed laser deposition technique used for cluster formation for both substrates, the obtained experimental results allow concluding the substantial role of the substrate (semimetal crystalline and insulating amorphous) on the thermodynamical properties of nanoclusters. The mechanism for the solid-liquid phase transition of nano-size clusters including the role of fluctuations and surface melting is discussed. | CA 3 |
| 10:00 | Break | |
| Properties I : Eric Mittemeijer | ||
| 10:30 | Nanocrystalline alloys from thin films and wires to bulk materials Authors : Ralph Spolenak Laboratory for Nanometallurgy, Department of Materials, ETH Zurich Affiliations : Resume : Nanocrystalline metals offer both high strength and reasonable fracture toughness in terms of mechanical properties. The current talk addresses
the effect of alloying elements on the mechanical properties of nanocrystalline metals for thin film applications, such as wearable electronics and bendable displays and how the observed phenomena can be extrapolated to bulk materials. The prerequisite for an extrapolation to bulk materials is the understanding of scaling behavior (size effects) in e.g. yield strength, fracture toughness, viscoelasticity and optical properties. The materials systems range from Au and Pt to Cu, Ni and Al alloys. | CB 1 |
| 11:00 | Nanometer size effect on structural and magnetic properties of La0.2Ca0.8MnO3 Authors : V. Markovich,1 D. Mogilyansky,2 I. Fita,3,4 R. Puzniak,3 A.Wisniewski,3X. D. Wu,5 K. Suzuki,5 S. Chen,5 and G. Gorodetsky1 1Department of Physics, Ben-Gurion University of the Negev, 84105 Beer-Sheva, Israel 2 The Analytical Research Services and Instrumentation Unit, Ben-Gurion University of the Negev, 84105 Beer-Sheva, Israel 3Institute of Physics, Polish Academy of Sciences, Aleja Lotnikow 32/46, 02-668 Warsaw, Poland 4Donetsk Institute for Physics & Technology, National Academy of Sciences, 83114 Donetsk, Ukraine 5Depatment of Materials Engineering, Monash University, Clayton, Victoria 3800, Australia Affiliations : Resume : We report on structural and magnetic properties of La0.2Ca0.8MnO3 nanoparticles (NP) with average diameter ranging from 15 to 37 nm. Synchrotron experiments performed on these NP samples at the temperatures (T) 80-300 K have shown that a structural transition: orthorhombic Pnma to monoclinic P21/m space group occures upon cooling.from room temperature. This transition is associated with orbital ordering, which is progressively suppressed for decreasing particle size. The magnetization of the NP samples exhibits ferromagnetism at T > 200 K, antiferromagnetic (AFM) ordering within the NP core below TN (143 K for 15 nm and 173 K for 37 nm NP) and an emergence of unspecified FM phase at T < 100 K. It was found that the NP samples exhibit a monotonous enhancement of weak ferromagnetism with decreasing particle size. The high-T ferromagnetic (FM) contribution may be attributed to surface magnetization while the low-T FM contribution appears as a result of spin canting within AFM core or is developed at some interfaces inside core. Magnetic hysteresis loops exhibit size dependent exchange bias (EB) effect displayed by horizontal HEB and vertical MEB shifts in field cooled processes. HEB, MEB, as well as remanent magnetization Mr and coercive field HC at low T, exhibit non-monotonic size dependence, which can be ascribed to the variation of the uncompensated surface spins and surface anisotropy or to a transition from multi-domain to mono-domain state within the core. The EB for 15 nm NP shows a non-monotonic variation of HEB and MEB as well as of HC at variation of T at which the cooling field Hcool is applied. This indicates that the volume of the FM phase, interfacial exchange, and the topology of interface depends on the protocol of application of Hcool. | CB 2 |
| 11:15 | Size-dependent properties of supported metal oxide nanoclusters Authors : Anna Iwaszuk Michael Nolan Tyndall National Institute, University College Cork, Cork, Ireland Affiliations : Resume : Meta oxides such as titanium dioxide and cerium dioxide are of great interest in many technology applications but are also important for fundamental investigations. Nanoclusters of these oxides are of great interest for the photocatalysis and catalysis. The tunability of the electronic properties and reactivity of nanoclusters and advances in synthesis and characterisation makes them very attractive materials. We present the results of first principles simulations of TiO2 and CeO2 nanoclusters supported on the rutile TiO2 (110) surface and TiO2 nanoclusters supported on CeO2 (111) surface; the nanoclusters are up to 2nm diameter. Our primary findings are: (i) the clusters interact strongly with the surface creating bonds between the cluster and the surface. (ii) the clusters interact strongly with the surface and oxygen atoms are present that are shared by the cluster and the support. (iii) The band gap can be modulated by interface formation and electrons and holes separated upon excitation. The formation of the interface leads to highly reactive oxygen, compared to the unsupported cluster and the surface, however, results on CO oxidation show that a moderate activity is necessary. These results demonstrate size dependent properties of oxide nanoclusters and show that supported oxide clusters are potentially useful for photocatalytic and catalytic applications. | CB 3 |
| 11:30 | Size dependence of the structure and magnetism in ZnFe2O4 Authors : E. G. Moshopoulou1*, M. Milanovic2, K. Giannakopoulos1,3, O. Isnard4, E. Devlin1, D. Stamopoulos1, A. Kontos5, V. V. Srdic2 1Institute of Materials Science, National Center for Scientific Research «Demokritos»,15310 Agia Paraskevi Attikis, Greece 2Department of Materials Engineering, Faculty of Technology, Bul. Cara Lazara 1, Novi Sad, Serbia 3Institute of Microelectronics, National Center for Scientific Research «Demokritos»,15310 Agia Paraskevi Attikis, Greece 4Institute N?-CNRS and University Joseph Fourier, Grenoble France 5Institute of Physical Chemistry, National Center for Scientific Research «Demokritos»,15310 Agia Paraskevi Attikis, Greece *evagelia@ims.demokritos.gr Affiliations : Resume : Size control over the magnetism of complex nanoparticles is one of the most challenging and yet rewarding areas in solid state science. It can advance our basic understanding of the role of geometry and size on the magnetic states, and enable new applications. Spinel ferrite nanoparticles are very attractive systems in this regard, because the spinel structure is of the most complex and adaptive structures and it can evolve with the size and shape of the nanoparticles, resulting in novel or enhanced properties. Among the wide variety of spinel ferrites, we chose ZnFe2O4 (and doped derivatives) as model system because of its complex, and not yet fully explored relationship between preparation method, form (single-, poly-, nano- crystalline), crystal structure and magnetic states and parameters. Nanoparticles of ZnFe2O4 (and doped derivatives) were characterized by a wide variety of techniques: powder X-ray and neutron diffraction, electron microscopy, Mossbauer and Raman spectroscopies and magnetization measurements. The influence of the size on the structural and magnetic properties of nano-crystalline ZnFe2O4 was explored and compared with the corresponding properties of single crystalline, thin films and coarse grained ZnFe2O4. It was found that ZnFe2O4 nanoparticles exhibit different structural and magnetic properties compared with their bulk counterparts: while they maintain the average spinel cell, there is significant rearrangement of the cations on the tetrahedral and octahedral sites of the structure, resulting in magnetic transitions and parameters clearly different from the corresponding ones of their bulk counterparts. | CB 5 |
| 11:45 | Strong resistance of 1D silicene nanoribbons towards oxidation and sp2 hybridization of its silicon valence orbitals Authors : P. De Padova*1, C. Quaresima1, B. Olivieri2, P. Perfetti1 and G. Le Lay3 1Consiglio Nazionale delle Ricerche-ISM, via del Fosso del Cavaliere, 00133 Roma, Italy 2 Consiglio Nazionale delle Ricerche-ISAC, via Fosso del Cavaliere, 00133 Roma, Italy 3 CINaM-CNRS, Campus de Luminy, Case 913, 13288 Marseille Cedex 9, France Affiliations : Resume : Here, we present the chemistry of silicene [1-3], a new allotropic form of silicon, that is a one atom thick sheet of silicon arranged in a honeycomb structure, through its interaction with molecular oxygen, and the character of its Si-Si bonds by reflection electron energy loss spectroscopy (REELS). The oxidation process remarkably starts at very high oxygen exposures, about 104 times higher than on the clean Si(111)7x7 surface. This unprecedented behaviour demonstrates the very low reactivity of honeycomb-like silicon to molecular oxygen, similarly to graphene. Intentionnaly created defects on silicene by Ar+ sputtering boost the oxygen uptake, fancying the possibility, by controlling the defects topography, to prototype nanometric metal/oxide semiconductor devices.
REELS spectra taken at the Si K absorption edge of silicon (~1.840 keV) show the presence of two distinct loss structures attributed to 1s‡π* and 1s‡σ* transitions, which confirm the sp2 hybridization of the silicon valence orbitals such as those observed in the carbon atomic bonds of graphene.
Electronic properties of clean silicene nnanoribbons will be presented by photoemission measurements, which showed the one-dimensional (1D) character of the 5×2/5×4 silicene nanoribbons (SiNRs), revealing the signature of the 1D Dirac cone at the Brillouin zone corner [1], which characterizes the massless relativistic charge carriers, as in the case of graphene and/or graphite.
References
[1] P. De Padova, C. Quaresima, C., P. M. Sheverdyaeva, P. Moras, C. Carbone, D. Topwal, B. Olivieri, A. Kara, H. Oughaddou, B. Aufray, and G. Le Lay, Appl. Phys. Lett. 96, 261905 (2010).
[2] P. De Padova, C. Quaresima, P. Perfetti, B. Olivieri, C. Léandri, Aufray, S. Vizzini, and G. Le Lay, Nano Lett. 8, 271 (2008).
[3] P. De Padova, C. Léandri, S.Vizzini, C. Quaresima, Perfetti, B. Olivieri, H. Oughaddou, B. Aufray, and G. Le Lay, Nano Lett. 8, 2299 (2008). | CB 6 |
| 12:00 | Lunch | |
| Synthesis I : Yener Kuru | ||
| 13:30 | Iron oxide nanoparticle synthesis from liquid spray flame in a low pressure environment Authors : S.Hardt1, H. Wiggers1,2, I. Wlokas1, C. Schulz1,2 1IVG, University of Duisburg-Essen 2CeNIDE, Center for NanoIntegration Duisburg-Essen Lotharstraße 1, 47057 Duisburg, Germany Affiliations : Resume : Iron-oxide nanoparticles are of major interest for catalytic, magnetic and electronic applications. Beside of these classic applications, they are used as a contrast agent and for magneto-fluids. A well-established synthesis route, especially for medical and catalytical applications, is the liquid-phase synthesis enabling for very small particles while the common route for large-scale production is based on flame synthesis. Typically, these particles are in the size regime of a few ten nanometer in diameter.
We developed a new, low-pressure flame spray process, which allows for a (scalable) synthesis of very small nanoparticles. The setup can be operated between 200 and 1300 mbar absolute.
Iron oxide nanoparticles were prepared from a solution of Fe(III)-acetylacetonate in toluene. Ex-situ diagnostics such as BET, HR-TEM and XRD were used to characterize the as-prepared nanoparticles. We find that our setup enables the formation of crystalline nanoparticles sizing between 3 and 7 nm depending on pressure and precursor concentration. For basic understanding with respect to particle formation we used computational fluid dynamics. Spray formation and droplet evaporation is modeled in an Euler-Lagrange formulation. The spray flame is simulated in 3D using simplified reaction kinetics while the population balance equations are solved using a monodisperse approach. It is found that particle diameters from experiment and simulation fit suprisingly well. | CC 1 |
| 13:45 | High Throughput of Silicon Nanocrystals in Expanding Thermal Plasma for Photovoltaic Applications Authors : I. Dogan1, N.J. Kramer1, M.A. Verheijen1, K. Dohnalova2, T. Gregorkiewicz2 and M.C.M. van de Sanden1 1 Department of Applied Physics, Eindhoven University of Technology, The Netherlands 2 Van der Waals Zeeman Institute, University of Amsterdam, The Netherlands Affiliations : Resume : Silicon nanocrystals (Si-NCs) have been drawing attention since they have shown to exhibit unique physical and chemical properties like size dependent luminescence, improved charge storing capacity and increased surface reactivity. As an example, the size dependent optical properties of Si-NCs show great promise for highly efficient third generation solar cells. Si-NCs could be used as spectrum down converters by using the excess energy of a hot photon to generate multiple exciton pairs. For successful industrial applications, the main issues on Si-NC synthesis are size control, surface engineering for improved optical properties, and high throughput. Although many well known techniques have been employed for Si-NC synthesis, none of them have the capability to meet all the critical requirements at the same time, especially when the issue comes to large scale production. Our goal is to show that it is possible to fulfill these demands with an ultimate solution by using the advantages of the remote expanding thermal plasma (ETP) technique. Synthesis of Si-NCs occurs in a remote Ar/SiH4 plasma, in which the Ar plasma has been ignited by a cascaded DC arc source and SiH4 has been injected from a ring placed in downstream. The plasma chemistry involves a reaction sequence of ion-SiH4 charge exchange and subsequent addition of SiH4 molecules. Self heating of the nanoparticles via H-H association and ion-electron recombination on the surface leads to full crystallization of spherical nanoparticles. This realizes nearly complete conversion of SiH4 into Si-NCs with very high throughputs of 25mg/min, which is the fastest Si-NC deposition rate reported in the literature so far. During the synthesis, we have the freedom of tuning the size of the Si-NCs by controlling the flow rates of SiH4 and Ar, i.e. the residence time in the plasma. Synthesized Si-NCs have a bimodal distribution of small (4-7nm) and big (50-80nm) sizes as confirmed by TEM, which is a consequence of the reactor geometry: a central plasma jet with a shorter residence time and a surrounding recirculation vortex with longer residence time. In addition, the bimodality has been analyzed with Raman spectroscopy by studying the asymmetry and shift in the transverse optical vibration mode of bulk-Si at 521cm-1. For the demonstration of the hypothesis of bigger nanocrystal formation during recirculation, we have realized the geometrical separation of central region from the vortices by means of an adjustable quartz tube, which is placed in the center of the reactor. Consequently, a decrease in the number of bigger nanocrystals has been observed on the substrate as a function of increasing tube length. Photoluminescence spectroscopy has confirmed the nature of monodisperse size distribution of only small Si-NCs (4-7nm) leading to luminescence in the region 600-900nm. Observation of luminescence illustrates the quality of the nanocrystal surface; however, it is possible to functionalize the surface further by using suitable passivating gases during the synthesis. An outlook on how to geometrically separate the big and small Si-NCs further to obtain exclusively monodisperse size distribution will be presented. | CC 2 |
| 14:00 | Synthesis and characterisation of high entropy alloys from elements with close atomic radii Authors : C.E.A. Grigorescu1, D. Savastru1, M. Balaceanu1, S.A. Manea2, O. Monnereau3, L. Tortet3, R. Notonier4 1. National Institute R&D Optoelectronics INOE 2000, 409 Atomistilor Str., Magurele, P.O. Box MG-5, 77125 Romania 2. National Institute R&D materials Physics, Magurele, Romania 3. Laboratoire Chimie Provence, Universite de Provence, Marseille, France Service Commun de Microscopie, Universite de Provence, Marseille, France Affiliations : Resume : High entropy alloys were developed in recent years by Yeh et al. [1,2], who defined them as composed of at least five principal elements with the concentration of each principal element being between 35 and 5 at.%. The properties of these alloys offer the potential to be used in many applications, such as tools, molds, dies, mechanical parts and furnace parts, which require high strength, thermal stability, and wear and oxidation resistance, with application temperatures up to 800 °C.
Our work concerns the synthesis and characterization of bulk alloys composed of principal elements with close atomic radii, with strict concentrations of 1 at% each. FeCoNiGeCu and TiAlCuNiGeCo have been prepared in bulk using the Vertical Gradient Freeze technique. Their properties were investigated by XRD, SEM, EDS and TGA in a magnetic field. Vickers tests show the highest hardness value for the 5-component alloy. A comparison with standard Ni-based superalloys is made.
[1] S. Ranganathan, Current Sci. 85 (2003) 1404–1406.
[2] J.W. Yeh, S.K. Chen, S.J. Lin, J.Y. Gan, T.S. Chin, T.T. Shun, C.H. Tsau,
S.Y. Chang, Adv. Eng. Mater. 6 (2004) 299–303.
[3] Chung-Chin Tung et al., Materials Letters 61 (2007) 1–5 | CC 3 |
| 14:15 | Inhomogeneous Composition of Alloyed Iron-Platinum Magnetic Nanoparticles Synthesized at Low Temperature Authors : Shu Chen,a,b Donald A. MacLaren,c Richard T. Baker,b John N. Chapman,c Stephen Lee,a David J. Cole-Hamilton,b Pascal Andr?,d* a- SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews, Fife, KY16 9SS (UK) b- EaStCHEM, School of Chemistry, University of St Andrews, St Andrews, Fife, KY16 9ST (UK) c- SUPA, School of Physics and Astronomy, The University of Glasgow, Glasgow G12 8QQ (UK) d- Chemistry and Materials Physics Building, RIKEN, 2-1 Hirowasa, Wako, Saitama, 351-0198 (Japan) E-mail: Pascal.Andre@st-andrews.ac.uk Affiliations : Resume : Iron platinum alloy nanoparticles (FePt nPs) are intensely interesting magnetic materials because its properties can combining or include above room temperature Curie temperature, high saturation magnetic moment and magneto-crystalline anisotropy along with strong chemical stability. This makes FePt a promising candidate for technological applications ranging from ultra high density recording media to bio-medical applications.
As colloids they are often prepared by thermal decomposition at high temperature, even though room temperature syntheses offer in contrast a very attractive pathway that could dramatically simplify nPs fabrication. However, a major hurdle has yet to be overcome: the inhomogeneous composition of the products.
Identifying the inhomogeneous composition of the products as the major hurdle of such syntheses, we present and discuss data including “synthesis time, iron precursors and reducing agent” combined with ICP-EOS, XRD, TEM, nanometric EDX, and SQUID magnetometry in order to identify and understand the effect of the ionic precursor and the reducing agent on the composition of alloyed nanomaterials. We demonstrate that the nanoparticle composition could be modulated by using faster reducing agents as well as iron (II) salts which are less susceptible to base hydrolysis than iron (III) salts.
The strategy we highlight here should be applicable to other alloy nPs fabricated by low temperature co-reduction in aqueous solution. | CC 4 |
| 14:30 | Selective Growth of Monoclinic and Tetragonal Zirconia Nanocrystals in Hydrothermal Condition Authors : Kazuyoshi Sato1, Takayuki Takarada1, Satoshi Ohara2,Hiroya Abe2 1. Department of Chemical & Eenvironmental Engineering, Graduate School of Engineering, Gunma University, 1-5-1 Tenjin-cho, Kiryu, Gunma, 376-8515 Japan 2. Joining and Welding Reserach Institute, Osaka University, 11-1 Mihogaoka, Ibaraki, Osaka,567-0047 Japan Affiliations : Resume : We demonstrate for the first time a selective growth of single-crystalline pure monoclinic and tetragonal ZrO2 nanocrystals of <10 nm diameter, driven by controlling their surface energy through capping with and without N(CH3)4+. The nanocrystals were grown in the hydrothermal condition at 150 ºC. The nanocrystals capped by N(CH3)4+ is confirmed to have less defective pure monoclinic phase, while those without capping have pure tetragonal phase with highly disordered oxygen vacancies. The phase control can be explained simply by their surface energy control. The N(CH3)4+ capping on the surface oxygen site can reduce the surface energy low enough to stabilize monoclinic phase. In contrast, bare surface oxygen site has higher energy, thereby lower surface energy tetragonal phase was spontaneously formed. The present concept will be a promising universal approach to control the crystal phases and lattice defects of technologically important oxide nanocrystals. | CC 5 |
| 14:45 | Synthesis of amorphous and nanocrystalline alloys for industrial applications Authors : V. Nosenko 1, A. Nosenko 2, M. Zakharenko 2, A. Kochkubey 3 1 G.V. Kurdymov Institute for Metal Physics of National Academy of Sciences of Ukraine, 36 Vernadsky Str., 03142, Kyiv, Ukraine, nosenko@imp.kiev.ua 2 Department of Physics, Taras Shevchenko National University of Kyiv, 64,Volodymyrska st., 01601, Ukraine 3 MELTA Ltd., 36 Vernadsky Str., 03142, Kyiv, Ukraine. Affiliations : Resume : New routes for synthesis of amorphous and nanocrystalline alloys for applications in efficient devices, such as magnetic cores for ground leakage current sensors, current measuring transformers (converters), powerful medium frequency, broadband and pulse small-size transformers, filter chokes, reactors, storage transformers and ferroprobes, are reported. From the practical standpoint the most important feature is high heat-time stability of initial magnetic permeability of cores that is provided by using of new methods of their final treatment. This treatment (impregnation with liquid heat-resistant materials and application of new polymeric coatings) ensures minimization of the influence of packaging on cores characteristics. The full-scale production of new precision rapidly quenched amorphous and nanocrystalline alloys is organized in the Institute for Metal Physics, NAS Ukraine and research-and-production enterprise MELTA Ltd. Special advantages of magnetic cores made of these alloys are magnetostriction close to zero, high initial (1500 - 160000) magnetic permeability and extraordinarily low level of core loss. Various special treatments of finished cores allow obtaining both linear (flat) and nearly square remagnetization loops depending on the purpose of industrial application of the magnetic cores. | CC 6 |
| 15:00 | Patterning strategies for micellar synthesized metal nanoparticles based on soft-lithography and mask removal Authors : A. Riskin(1), C. De Dobbelaere(1), L. Shan(2), H.G. Boyen(2), J. D’Haen(2), A. Hardy(1,2) and M.K. Van Bael(1,2) (1): Hasselt University, Institute for Materials Research, Inorganic and Physical Chemistry Group, Agoralaan Building D, B-3590 Diepenbeek, Belgium (2): IMECvzw division IMOMEC, Wetenschapspark 1, B-3590 Diepenbeek, Belgium Affiliations : Resume : Micellar solutions have generated plenty of interest in recent years due to their flexibility in the synthesis and deposition of metallic nanoparticles. Many applications in the fields of micro-electronics and catalysis demand the patterned deposition of these particles. Patterning of such nanoparticle loaded micelles can be done in-situ using e-beam lithography or through a pattern formed by e-beam- or photo-lithography. These techniques, however, are time consuming and demand expensive equipment. In our research, we present an easy alternative for the creation of substrates patterned with metal nanoparticles based on soft-lithography. A submicron-sized pattern was replicated in a resist on a silicon substrate and the scum layer in between was removed using an UV-ozone treatment. Dipcoating a micellar solution under the right conditions yielded vertical strips of metal loaded micelles which were transformed into nanoparticles using a subsequent plasma treatment. For the fabrication of isolated islands of nanoparticles a premade test structure was used consisting of holes with a diameter ranging from 300 to 140 nm. Spincoating of a micellar solution filled the holes with a matrix made of solidified polystyrene around polyvinylpyridine micellar cores loaded with metal salt. Subsequent etching of the template using hydrofluoric acid yielded free-standing pillars of the aforementioned material. Plasma treatment of these pillars resulted in circular patterned nanoparticles. | CC 7 |
| 15:15 | Self-assembly of Nanostructured ZnO-based Homojunction by Two-step Method Authors : School of Materials Science and Engineering, University of Science and Technology of Beijing, Beijing 100083, China Affiliations : Resume : In recent years, one-dimensional semiconductor nanostructures have attracted much attention because of their excellent physical and chemical properties. Zinc oxide (ZnO) is an important semiconductor material with a wide direct band-gap of 3.37 eV and possesses high exciton binding energy of 60 meV. It has great potential application in photodetectors, field-effect transistors, and other optoelectronic devices. ZnO nanostructures are one of the most promising functional materials with many attractive properties. Recently, fabrication of nanostructured ZnO homojunction has stimulated great interest due to their applications in nanodevices. Sun et al. synthesized ZnO nanowires by wet chemical method on various ZnO templates [1]. Chen MT et al. fabricated the catalyst-free p-n homojunction ZnO nanowires arrays in which the phosphorus and zinc served as p- and n-type dopants, respectively [2]. ZnO homojunctions were also synthesized by P-doped ZnO nanorods grown on undoped ZnO nanorods [3,4]. There were also some reports on nanostructured ZnO deposited on the p-type ZnO films to form the homojunctions [5,6]. Most of these reports were focused on the formation of axial nanostructured ZnO junction, while, there are few report on the radial nanostructured ZnO junction.
In this work, self-assembly of radial nanostructured ZnO homojunction were synthesized by a kind of two-step method. In-doped ZnO microstructures were first deposited on a cleared silicon substrate by chemical vapor deposition method (CVD), and then a layer of undoped ZnO covers on the In doped ZnO rods via solution method. A homojunction was fabricated because the In-doped ZnO exists inside and undoped ZnO covers at the outer layer. We provide a supplementary growth mechanism to explain the formation of nanostructured ZnO homojunction. The interface of In doped ZnO nanorods supply nuclear sites for the growth of ZnO, and the ZnO nanocrystals are easy to grow up and coalesce into hexagonal wall. We also measured the room temperature photoluminescence (PL) spectra for In-doped ZnO film synthesized by CVD method and that of final junction nanostructures formed by solution method. It clear reveals that the ultraviolet (UV) emission peak of In doped ZnO has an obvious blue-shift compare to that of final junction nanostructures, which agrees with the obvious report that the ultraviolet emission of ZnO nanorods shifts to high energy side with In doping [7]. PL spectra show that the intensity of the green emission obviously decreases after ZnO layer coating, which means that the ratio of intensity of UV emission to that of green emission increases. It may ascribe to the capping treatment compensating the defects at the surface of In doped ZnO, and suppressing the defect luminescence of ZnO nanostructures. The PL spectra also suggest that the outer layer is quite different from the inside. This work provides a very useful way to fabricate junctions, which are very important for designing optic-electrical nanodevices.
References
[1] Ye Sun, Neil A. Fox, Gareth M. Fuge, and Michael N. R. Ashfold, Toward a Single ZnO Nanowire Homojunction, J. Phys. Chem. C,114 (2010) 21338-21341.
[2] Min-Teng Chen, Ming-Pei Lu, Yi-Jen Wu, Jinhui Song, Chung-Yang Lee, Ming-Yen Lu,
Yu-Cheng Chang, Li-Jen Chou, Zhong Lin Wang, and Lih-Juann Chen, Near UV LEDs Made with in Situ Doped p-n Homojunction ZnO Nanowire Arrays, Nano Lett. 10 (2010) 4387-4393.
[3] Xuan Fang, Jinhua Li, Dongxu Zhao, Dezhen Shen, Binghui Li, and Xiaohua Wang, Phosphorus-Doped p-Type ZnO Nanorods and ZnO Nanorod p-n Homojunction LED Fabricated by Hydrothermal Method, J. Phys. Chem. C, 113 (2009) 21208-21212.
[4] X. W. Sun, B. Ling, J. L. Zhao, S. T. Tan, Y. Yang, Y. Q. Shen, Z. L. Dong, and X. C. Li, Ultraviolet Emission from a ZnO Rod Homojunction Light-emitting Diode, Appl. Phys. Lett. 95 (2009) 133124.
[5] Manoj Kumar, Jyoti Prakash Kar, In-Soo Kim, Se-Young Choi, and Jae-Min Myoung, Fabrication of As-doped p-type ZnO Thin Film and ZnO Nanowires Inserted p-n Homojunction Structure, Appl Phys A, 97 (2009) 689-692.
[6] H. Sun, Q. Zhang, J. Zhang, T. Deng, and J. Wu, Electroluminescence from ZnO Nanowires with a p-ZnO Film/n-ZnO Nanowire Homojunction, Appl. Phys. B, 90 (2008) 543-546.
[7] M. N. Jung, J. E. Koo, S. J. Oh, B. W. Lee, W. J. Lee, S. H. Ha, Y. R. Cho, and J. H. Chang, Influence of Growth Mode on the Structureal. Optical, and electrical Properties of In doped ZnO Nanorods, Appl. Phys. Lett. 94 (2009) 041906. | CC 8 |
| 15:30 | Break | |
| Poster I : to be announced | ||
| 16:00 | Nanofluid, Organic Self-Assembled Nanoparticles and Thin Films Authors : Ramesh Jagannathan Affiliations : Resume : We present evidence of a novel nanostructured fluid, a nanofluid, composed of molecular clusters of a polar organic dye and surfactant. These are not nanoparticles dispersed in a solvent; there are no solvent molecules present. These materials, which are solids under ambient conditions, are non-reactively precipitated from a compressed CO2 solution, resulting in a liquid-like material, which we call a nanofluid. The precipitated dye±surfactant clusters are 1±4 nm in size. This nanofluid exhibits intense luminescent signatures, which are significantly blue-shifted with respect to the dye powder or a solution of it. The X-ray diffraction pattern did not show any structure in the low-angle regime. The fluorinated surfactant is highly soluble in compressed CO2. The polar dye does not dissolve in compressed CO2 but is solubilized by electrostatic interactions with the surfactant head groups. We believe that the ultrafast and controlled precipitation from compressed CO2 preserves the electrostatic coupling and promotes a structured molecular cluster.
The organic nanoparticles prepared from our constant (P,T) compressed CO2 process demonstrate a strong tendency to rapidly self-assemble into highly aligned superlattices at room temperature when solution-cast from dispersions or spray-coated directly onto various substrate. The nanoparticle dispersions are stable for years. Functional organic light-emitting diodes (OLEDs) – which have the same host dopant emissive-material composition - with process-tunable electroluminescence have been built with these nanoparticles, indicating the presence of novel nanostructures. For example, only changing the conditions of the precipitation process changes the OLED emission from green light to yellow. | PC1 1 |
| 16:00 | Nuclear Magnetic Resonance Study of Inorganic NanoMaterials Authors : A. M. Panich, Department of Physics, Ben-Gurion University of the Negev, Beer Sheva 84105, Israel Affiliations : Resume : Nuclear Magnetic Resonance (NMR) is an excellent tool in studying and characterizing nanomaterials at the atomic level. I will report on a NMR study of the local crystal structure, electronic structure, nature of chemical bond and defects in boron nitride nanotubes, tungsten and molybdenum sulfide fullerene-like nanoparticles, thallium diselenide nanorods, and vanadium oxide nanotubes. The properties of the corresponding bulk samples vary from wide gap semiconductors to semimetals. The obtained data on nanosized compounds are compared with those of bulk ones. Our research elucidates when the properties of nanomaterials differ significantly from those of bulk samples, and when this difference is small or nearly absent. | PC1 2 |
| 16:00 | Nuclear Magnetic Resonance Characterization of NanoMaterials Authors : A. M. Panich, Department of Physics, Ben-Gurion University of the Negev, Beer Sheva 84105, Israel e-mail: pan@bgu.ac.il Affiliations : Resume : Nuclear Magnetic Resonance (NMR) is an excellent tool in studying nanomaterials at the atomic level. I will report on NMR study of the local crystal structure, electronic structure, nature of chemical bond, defects and impurities in purified and functionalized detonation nanodiamonds, polyhedral multi-shell carbon nanoparticles, doped fullerenes, boron nitride nanotubes, tungsten and molybdenum sulfide fullerene-like nanoparticles, thallium diselenide nanorods and vanadium oxide nanotubes. Our latest study of nanodiamonds decorated by copper and cobalt ions shows their possible applications in spintronics and biomedicine. The properties of the corresponding bulk samples vary from insulators and wide gap semiconductors to semimetals. The obtained data on nanosized compounds are compared with those of bulk ones. Our research elucidates when the properties of nanomaterials differ significantly from those of bulk samples, and when this difference is small or nearly absent. | PC1 3 |
| 16:00 | EFFECTIVE MEASUREMENT OF ENVIRONMENT FACTORS USING NANOTECHNOLOGY Authors : Arun Kumar Santhana Srijayanth V S Affiliations : Resume : To provide a new methodology to measure temperature, humidity, radiation, pressure of a remote area using nanotechnology. Currently, the measurement of environmental factors is done using ageing, less accurate and traditional devices. Such devices generate error in the form of linearity, accuracy, sensitivity, disruption. We are proposing a methodology by using Nanotechnology.
In the current methodology or techniques, the factors are measured using sensors. The common problem with sensors in the present method is that, they soon get disrupted by the environmental issues and they have also been stolen, damaged and worn-out at some instances.
So, we came out with our new idea. In order to improve the system and making it advantageous, nanotechnology is used. They are invisible and they can be placed in the environment, free from external disturbances, not easily damaged and offer greater accuracy than the existing method. The module we have planned is an inbuilt sensor device with a built-in transceiver. It will also have an attached power bank (battery) along with the solar panels, in order to receive solar energy and store it during the day.
The major advantage of this system is, the data collected from the location is transmitted to the base-station regularly by using Mesh Network that exists among these nano devices thereby removing the cost or investment for communication. They are easy to maintain and can be easily replaced.
Using the proposed module we have successfully measured temperature, humidity, radiation, pressure, impact and vibration | PC1 4 |
| 16:00 | Dependence of the value of the d-metal atomic magnetic moment on the chemical structure of nanoforms Authors : I.N. Shabanova, N.S. Terebova Physicotechnical Institute, The Ural Division of the Russian Academy of Sciences, 132 Kirov St., Izhevsk, 42600 e-mail: xps@fti.udm.ru Affiliations : Resume : A model connecting the parameters of the X-ray electron 3s-spectra with the change of the spin state on metal d-atoms is used for the determination of the atomic magnetic moment of nanoforms depending on the d-metal shell filling, the d-electron localization, the influence of the additions of sp elements in the polymer matrix and the nanoform size.
The results obtained show the change of the parameters of Me3s spectra in nanostructures, in contrast to massive samples. In the nanoforms, the number of noncompensated d electrons increases on the atoms of Fe, Co and Ni metals, and noncompensated d electrons appear on the Cu atoms. It is connected with the participation of d(Me) and p(X) electrons in the hybridized chemical bond. Consequently, in contrast to massive samples, in nanostructures the atomic magnetic moment increases. The study of the dependence of the value of the d-metal atomic magnetic moment on the nanostructure sizes shows that the atomic magnetic moment grows with decreasing nanoparticle sizes. | PC1 5 |
| 16:00 | EFFECTIVE MEASUREMENT OF MICRO METEOROLOGICAL PARAMETERS USING NANOTECHNOLOGY Authors : Arunkumar Santhana, V S Srijayanth Affiliations : Resume : To provide a new methodology to measure temperature, humidity, radiation, pressure of a remote area using nanotechnology. Currently, the measurement of environmental factors is done using ageing, less accurate and traditional devices. Such devices generate error in the form of linearity, accuracy, sensitivity, disruption. We are proposing a methodology by using Nanotechnology.
In the current methodology or techniques, the factors are measured using sensors. The common problem with sensors in the present method is that, they soon get disrupted by the environmental issues and they have also been stolen, damaged and worn-out at some instances.
So, we came out with our new idea. In order to improve the system and making it advantageous, nanotechnology is used. They are invisible and they can be placed in the environment, free from external disturbances, not easily damaged and offer greater accuracy than the existing method. The module we have planned is an inbuilt sensor device with a built-in transceiver. It will also have an attached power bank (battery) along with the solar panels, in order to receive solar energy and store it during the day.
The major advantage of this system is, the data collected from the location is transmitted to the base-station regularly by using Mesh Network that exists among these nano devices thereby removing the cost or investment for communication. They are easy to maintain and can be easily replaced. | PC1 6 |
| 16:00 | Dependence of the value of the d-metal atomic magnetic moment on the chemical structure of nanoforms Authors : N.S. Terebova, I.N. Shabanova Physicotechnical Institute, the Ural Division of the Russian Academy of Sciences Affiliations : Resume : A model connecting the parameters of the X-ray electron 3s-spectra with the change of the spin state on metal d-atoms is used for the determination of the atomic magnetic moment of nanoforms depending on the d-metal shell filling, the d-electron localization, the influence of the additions of sp elements in the polymer matrix and the nanoform size.
The results obtained show the change of the parameters of Me3s spectra in nanostructures, in contrast to massive samples. In the nanoforms, the number of noncompensated d electrons increases on the atoms of Fe, Co and Ni metals, and noncompensated d electrons appear on the Cu atoms. It is connected with the participation of d(Me) and p(X) electrons in he hybridized chemical bond. Consequently, in contrast to massive samples, in nanostructures the atomic magnetic moment increases. The study of the dependence of the value of the d-metal atomic magnetic moment on the nanostructure sizes shows that the atomic magnetic moment grows with decreasing nanoparticle sizes | PC1 7 |
| 16:00 | ELECTRICAL PROPERTIES OF NANOCOMPOSITE METAL-DIELECTRIC FILMS WITH INDUCTIVE IMPEDANCE Authors : J. Fedotova1), A. Fedotov2), A. Mazanik2), I. Svito2), T. N. Koltunowicz3), P. V. Zhukowski3), V. Fedotova4) 1) National Center of Particles and High Energy Physics of BSU, Minsk, Belarus 2) Belarusian State University, Minsk, Belarus 3) Lublin University of Technology, Lublin, Poland 4) Scientific-Practical Material Research Centre NAS of Belarus, Minsk, Belarus Affiliations : Resume : Granular nanocomposites FeCo-based ferromagnetic alloy – amorphous dielectric matrix has a special place among nanostructured materials. Depending on the metallic phase concentration x, the electrical properties of such mixtures can vary between those of the matrix and of the filler. The typical binary composite material has a critical concentration, percolation threshold xC, approached when a continuous cluster of filler particles is formed in the sample. As was shown in our previous studies, such composites around xC displayed inductive-like impedance. So the aim of this paper was to study the inductive parameters of (Fe0.45Co0.45Zr0.10)x(Al2O3)(1-x) films containing Fe0.45Co0.45Zr0.10 nanoparticles embedded into Al2O3 matrix and to examine the conditions which results in enhancement of inductive contribution in their impedance.
The impedance spectroscopy carried out in the films studied allowed to estimate inductive, capacitive and resistive contributions in equivalent circuits of the studied nanocomposites versus their composition x, atmosphere of preparation (Ar, Ar+O2), temperature (100 – 330 K) and other parameters. An inductive contribution was observed aroud the percolation threshold and enhanced in the films deposited in Ar+O2 ambient. It was evidenced that the current-conducting routes of electrons within the film bulk look like a system of nanocoils with different sizes and directions of “turns” embedded in the dielectric matrix. This confirmed that the studied film nanocomposites can be used as planar (noncoil-like) inductors in electrical and radio engineering (for examples, in ICs). | PC1 8 |
| 16:00 | Growth of nanoporous silicon dioxide thin films using porous alumina substrates Authors : M. Ghriba), M.Gaidi a)*, N. Khedhera), T. Ghriba), M. Ben Salemb) and H. Ezzaouiaa) a) Photovoltaic Laboratory Research and Technology Centre of Energy, Borj-Cedria Science and Technology Park, BP 95, 2050 Hammam-Lif, Tunisia. b) L3M, Department of Physics, Faculty of Sciences of Bizerte, 7021 Zarzouna, Tunisia Affiliations : Resume : In this paper, we report a cost-effective and highly reproducible method for the deposition of porous α-SiH thin films deposited by plasma enhancement chemical vapor deposition (PECVD) on porous alumina Al2O3, Who supports the formation of the SiO2 layers to 250°C. Due to the porous surface of the substrate and its narrow and long channels, the SiO2 thin films partially cover the pores of the alumina membranes and self-organized porous network structures are formed. The effect of anodisation currents on the microstructure of aluminium surface layer and SiO2 films was systematically studied by Atomic Force Microscopy (AFM) and Tranmission Electron microscopy (TEM), Raman spectroscopy and X-ray diffraction (XRD). The optical constants (n and k as a function of wavelength) of the films were obtained using variable angle spectroscopic ellipsometry (SE) in the UV-vis-NIR regions. The silicon layer (S.L) was modeled as a mixture of void, oxide silicon SiO2 and aluminum using the Bruggeman approximation. Based on this full characterization, it is demonstrated that the optical characteristics of the films are directly correlated to their micro-structural properties. A very bright photoluminescence (PL) was obtained and find to depend on anodisation current. The pore size depends on the thickness of the films. The morphology and the optical properties of the thin films consist of patterned islands which gradually coalesce together during the growth of the thin films.
Keywords: Porous aluminum, oxide silicon SiO2, ellipsometry, photoluminescence (PL).
*) Electronic mail: mounir.gaidi@crten.rnrt.tn.
**) Electronic mail: mondherghrib@yahoo.fr. | PC1 9 |
| 16:00 | Morphological and optical properties of nanocrystalline Si:H nano-wire and dot arrays with controllable porous alumina layer Authors : M. Ghrib, M.Gaidi *, N. Khedher, T. Ghrib, M. Ben Salemb) and H. Ezzaouia a) Photovoltaic Laboratory Research and Technology Centre of Energy, Borj-Cedria Science and Technology Park, BP 95, 2050 Hammam-Lif, Tunisia. b) L3M, Department of Physics, Faculty of Sciences of Bizerte, 7021 Zarzouna, Tunisia Keywords: Porous alumina layer, nanocrystalline Si:H nano-wire and dot arrays, ellipsometry. Affiliations : Resume : Based on the successful growth of hydrogenated nanocrystalline silicon (nc-Si:H) thin films with Si natural quantum wire and dots NQWD of 3–6 nm in mean size, we have fabricated nc-Si:H artificial quantum nano-wire and dot AQWD arrays on Si layer by a low-cost and industrialized plasmaenhanced chemical vapor deposition technique through free-standing ultrathin porous alumina layer (PAL). The influence of the microstructure of the nc-Si:H thin films on their optical properties was investigated through an extensive characterization. The effect of anodisation currents on the microstructure of aluminium surface layer and nc-Si films was systematically studied by Atomic Force Microscopy (AFM) and Tranmission Electron microscopy (TEM), Raman spectroscopy and X-ray diffraction (XRD).In order to well control the morphology of the nc-Si:H AQWD arrays, we have presented detailed information on the fabrication of PAL with controllable thickness (100– 1000 nm) and pore diameter (50–90 nm).The optical constants (n and k as a function of wavelength) of the films were obtained using variable angle spectroscopic ellipsometry (SE) in the UV-vis-NIR regions.The combination of the AQWD fabrication through PAL masks with the Si NQWD in nc- Si: H provides us an easy and practical way for the realization of nc-Si: H based nanodevice arrays with true quantum size effects. Based on this full characterization, it is demonstrated that the optical characteristics of the films are directly correlated to their micro-structural properties.
*) Electronic mail: mounir.gaidi@crten.rnrt.tn.
**) Electronic mail: mondherghrib@yahoo.fr. | PC1 10 |
| 16:00 | Femtosecond laser induced formation of Si nanocrystals and amorphous Si nanoclusters in SiOx films Authors : T.T. Korchagina1,*, V.A. Volodin1,2,, A.K. Gutakovsky1, L.I. Fedina1, M.A. Neklyudova1,2 . 1) Institute of Semiconductor Physics of SB RAS, Lavrenteva ave., 13, Novosibirsk 630090, Russia, *Taisiya999@mail.ru 2) Novosibirsk State University, Pirogova str., 2, 630090, Novosibirsk, Russia Affiliations : Resume : The SiOx films of various stoichiometry deposited on Si substrates with the use the co-sputtering from two separate Si and SiO2 targets were annealed by femtosecond laser pulses. Femtosecond laser treatments were applied for crystallization of amorphous silicon nanoclusters in silicon-rich oxide films. The treatments were carried out with the use of Ti-Sapphire laser with wavelength 800 nm and pulse duration about 30 fs. Regimes of crystallization of amorphous Si nanoclusters in the initial films were found. Effect of laser assisted formation of a-Si nanoclusters in the non-stoichiometric dielectric films with relatively low concentration of additional Si atoms was also observed. This approach is applicable for the creation of dielectric films with semiconductor nanoclusters on non-refractory substrates. Authors are thankful to professor I. Balberg and Dr. J. Jedrzejewski (Racah In-stitute of Physics, The Hebrew University) for samples. | PC1 11 |
| 16:00 | Lifetime enhancement in multicrystalline silicon by combining porous silicon and silicon nitride nanostructures Authors : M. Ben Rabha*, S. Belhadj Mohamed, W. Dimassi, M. Hajji. M. Bouaicha and Brahim Bessais Laboratoire de Photovolta?e, Centre de Recherches et des Technologies de l’Energie, Technopole de Borj-C?ia, BP 95, 2050 Hammam-Lif, Tunisia. * Corresponding author: e-mail rabha2222@yahoo.fr, Phone: 21679325160, Fax: 21679325825 Affiliations : Resume : A new passivation method is proposed for multicrystalline Silicon (mc-Si) wafers. In this experiment we combine the use of porous silicon (PS) and silicon nitride (SiNx) nanostructures. The latter covers the PS was investigated as a passivating and an antireflection coating (ARC). As a result of this surface treatment the total reflectivity of the solar cell emitter is reduced by about 6 % in the 400 - 1100 nm wavelengths range. The effective minority carrier lifetime calculated from the WCT-120 Photoconductance lifetime technique was found to be enhanced from 170 µs for PS treated cells, to about 443 µs for SiNx/PS treated ones. This improvement due to the passivation effect of PS and nitride in surface, grain boundaries and bulk of the mc-Si.
Keywords: Silicon nitride; porous silicon; reflectivity; lifetime. | PC1 12 |
| 16:00 | SAXS/DSC/WAXD Study of Temperature Evolution in Nanocomposite Polymer Electrolytes with Different Nanofillers Authors : Aleksandra Turković1,* Krunoslav Juraić1, Mario Rakić2, Pavo Dubček1and Sigrid Bernstorff3 1Institute "Ruđer Bošković", P.O. Box 180, HR-10002 Zagreb, Croatia 2Institute for Physics, Bijenička 52, HR-10002 Zagreb, Croatia 3Sincrotrone Trieste, ss. 14, km 163,5 Basovizza, 34012 Trieste, Italy Affiliations : Resume : Polymer electrolytes as nanostructured materials are very attractive components for batteries and opto-electronic devices. (PEO)8ZnCl2 polymer electrolytes were prepared from PEO and ZnCl2. The nanocomposites (PEO)8ZnCl2 themselves contained TiO2 (1), Al2O3, MgO, ZnO and V2O5 nanograins. In this work, the influence of the Al2O3, MgO, ZnO and V2O5 nanograins to the morphology and ionic conductivity of the nanocomposite was systematically studied by transmission small-angle X-ray scattering (SAXS) simultaneously recorded with wide-angle X-ray diffraction (WAXD) and differential scanning calorimetry (DSC) at the synchrotron ELETTRA. The SAXS/DSC/WAXD measurements yielded insight into the temperature-dependent changes of the grains of the electrolyte as well as into the effects of heating and cooling rates (1 °C/min, 0.5 °C/min and 0.25 °C/min). Environment friendly galvanic cells as well as solar cells of the second generation are to be constructed with nanocomposite polymer as electrolyte.
References
1) Aleksandra Turković, Pavo Dubček, Krunoslav Juraić, Antun Drašner and Sigrid Bernstorff, SAXS Studies of TiO2 Nanoparticles in Polymer Electrolytes and in Nanostructured Films, Materials 2010, 3, 4979-4993; doi:10.3390/ma3114979. | PC1 13 |
| 16:00 | NONLINEAR OPTICAL SPECTRA OF INTERSUBBAND TRANSITIONS IN A CdSe/ZnS/CdSe/SiO2 SPHERICAL QUANTUM DOT Authors : R. KOSTIĆ and D. STOJANOVIĆ University of Belgrade, Institute of Physics, P. O. Box 68, 11080 Belgrade, Serbia E-mail: rkostic@ipb.ac.rs Affiliations : Resume : CdSe/ZnS core/shell based structures are under detailed experimental and theoretical examination [1-5] in the last few years.
In this paper the electronic spectra and optical properties of one-electron spherical quantum dot (QD) are presented. QD is composed of CdSe core surrounded by ZnS shell (barrier) CdSe shell and finally by medium of very high potential barrier (SiO2) compared to CdSe. The energy eigenvalues of s, p and d states and corresponding wave functions were calculated using effective mass approximation. We have calculated oscillator strengths and the linear and third-order nonlinear intersubband optical absorption coefficients and refractive index changes as function of the QD dimension, incident photon energy and incident optical intensity for the 1s-1p, 1p-1d and 1p-2s transitions. | PC1 14 |
| 16:00 | Phonon Properties of Cd1-xMnxS Nanoparticles Authors : J. Trajic1, M. Romcevic1, N. Romcevic1, R. Kostic1, M. I. Comor2 1 Institute of Physics, P.O. Box 57, 11080 Belgrade, Serbia. 2 Vinča Institute of Nuclear Sciences, P.O. Box 522, 11001 Belgrade, Serbia. E-mail: jelena@ipb.ac.rs Affiliations : Resume : Nanosized particles of various direct-gap semiconductors exhibit unusual optical properties, which make them attractive as materials for nonlinear optical elements and luminescent devices. Manganese-doped nanocrystals are a class of materials with specific properties.
Phonon spectra of Cd1-xMnxS (x = 0; 0.01; 0.05; 0.1; 0.15; 0.3) nanoparticles (d ~ 4.5nm) have been investigated by far-infrared reflection (FIR) (spectral range 40 - 600cm-1, temperature range 80 – 300K) and Raman spectroscopy (100 – 700cm-1, 300K). Cd1-xMnxS nanoparticles have been synthesized by using aqueous solution precipitation.
We obtained interesting features in FIR spectra. The analysis of reflection spectra was done by a fitting procedure. A numerical model for calculating reflectivity coefficient of system of nanoparticles (Cd1-xMnxS) surrounded by (NaPO3)6 is used. There are expected modes of bulk CdS (240cm-1, 300cm-1), new modes connected with nano-size of CdS (150cm-1, 170cm-1) and additional modes (at 120cm-1, 190cm-1, 290cm-1) in Cd1 xMnxS nanoparticles which can be assigned to the presence of Mn. Raman spectroscopy gives us only the mode at 300cm-1 and its second harmonic.
The positions of some of these modes are discussed in the frame of linear chain model with both mass and force constant defects. The possibility of existence of ultra small nano-size clusters of MnS (~0.5nm) in Cd1-xMnxS nanoparticles is also discussed. | PC1 15 |
| 16:00 | Hydrogen accumulation/release versus nanostructure of Si:He Authors : A. Misiuk, A. Barcz, Institute of Electron Technology, 02-668 Warsaw, Poland; J. Bak-Misiuk, Institute of Physics, PAS, 02-668 Warsaw, Poland; A. Ulyashin, SINTEF Materials and Chemistry, 0314 Oslo, Norway Affiliations : Resume : Implantation of oxygen-containing Czochralski silicon with He+ ions at energy 300 keV and dose 5x10(15) cm(-2) and processing of Si:He at up to 1270 K (HT) under hydrostatic pressure up to 1.1 GPa (HP) results in a creation of buried nano-structured layer, with dimensions of He-filled cavities dependent on HT and HP [1,2]. The treatment of Si:He in deuterium plasma leads to accumulation of deuterium within the damaged layer, centred at projected range of He+, RHe. Deuterium content depends on the microstructure of Si:He [2]; deuterium is incorporated mainly within He-filled cavities, bonds to Si as well as to oxygen gettered near RHe. Subsequent annealing of Si:He,D results in recrystallization of amorphous Si created at implantation, in re-distribution of helium and deuterium, their out-diffusion, and in gettering of other admixtures (oxygen is the most abundant one) near RHe. Depending on the microstructure of Si:He,D, above 50% of introduced deuterium can be still contained within Si:He,D [3] even after it’s annealing for 1 h under atmospheric pressure at 873 K.
Our research is helpful for understanding the mechanisms of hydrogen accumulation in nano-structured Si layers and for design of materials for hydrogen storage.
[1] V. Raineri, S. Coffa, E. Szilagyi, J. Gyalai, E. Rimini, Phys. Rev. B 61, 937 (2000); [2] A. Misiuk, A. Ulyashin, A. Barcz, J. Bak-Misiuk, P. Romanowski, M. Prujszczyk, Phys. Status Solidi C 6, 1551 (2009). | PC1 16 |
| 16:00 | Size-dependence of magnetic Zn-Co-S clusters Authors : Maria Jadraque, Margarita Martin, Enrique Lomba, Eva G. Noya Instituto de Quimica Fisica Rocasolano, CSIC, Serrano 119, 28006 Madrid, Spain Affiliations : Resume : The possibility of synthesizing nanoscale materials, where individual stable clusters serve as elementary building blocks, is a subject of growing interest due to their potential technological applications. As the properties of clusters can be controlled by changing the size and composition, such synthesis may offer the potential to design materials with tailored properties.
Bulk, films and nanostructured materials composed by ZnO and ZnS doped with transition metal atoms (Co, Sc, Ti, V, Fe, Ni) have been found to exhibit magnetic order. Several nanofabrication methods for these materials have been reported, Pulsed Laser Deposition (PLD) amongst them. For instance, thin films of (ZnO)0.95(Co3O4)0.05 have been grown by this technique, using a Co doped ZnO PLD target prepared by standard solid state reaction.
Previously, we have experimentally studied the assembly and growth of individual Zn-Co-S stable clusters which may serve as aggregation nuclei for the synthesis of magnetic nanoscale objects. In this work we focused on the size-dependence of Zn-Co-S clusters magnetic properties. A computational study will be presented. The determination of the magnetic properties of the stochiometric (ZnS)m(CoS)n-m clusters, sulfur-rich S(ZnS)m(CoS)n-m clusters and metal-rich Con 1-mZnmSn clusters, up to n=7, have been performed for using VASP simulation package. | PC1 17 |
| 16:00 | Immobilization of Lutetium Bisphthalocyanine in Nanostructured Sensors for Phenol Detection Authors : Edson Giuliani Ramos Fernandes (University of São Paulo/IFSC/LNN) Laís Canniatti Brazaca (University of São Paulo/IFSC/LNN) Maria Luz Rodríguez-Méndez (University of Valladolid/E.T.S.I.I.) José Antonio de Saja (University of Valladolid/Faculty of Science) Valtencir Zucolotto (University of São Paulo/IFSC/LNN) Affiliations : Resume : Due to their health benefits, polyphenols are of great interest in food industry. Among the available methods used to quantify polyphenols in food, electrochemical sensors are the best choice due to low cost and simplicity. Amperometric sensors, for example, have been proved to be suitable for detection of a great variety of polyphenols mainly due to their low cost and potential for miniaturization. In this study we fabricated amperometric sensors based on poly(allylamine hydrochloride) (PAH) and Lutetium bisphthalocyanine (LuPc2) films assembled using the Layer-by-Layer (LbL) technique. The films were used as modified electrodes for catechol quantification. Electrochemical measurements were employed to investigate the catalytic properties of Lutetium bisphthalocyanine immobilized in the LbL films. The sensors presented excellent stability and a sensitivity of 20 nA/µM in a range from 10 to 1000 µM of catechol, at a work potential of +300 mV. Such high sensitivity and the possibility of reusing the films (which exhibited a lost in the response signal of c.a. 3% for 10 consecutive measurements) make them a good choice for fabrication of polyphenols sensing devices. | PC1 18 |
| 16:00 | From embedded to supported metal/oxide nanomaterials: Thermal behavior and modelling of structural evolution at elevated temperatures Authors : Stephanie B. Bubenhofer, Wendelin J. Stark and Robert N. Grass Institute of Chemical and Bioengineering, ETH Zurich, Switzerland Affiliations : Resume : The relation between structure and function is of major importance at material interfaces which often excel in terms of chemical or physical effects. Therefore, multi-phase nanocomposites (e.g. core-shell, janus-shaped and carrier-supported nanoparticles) attract attention due to their possibility to contact two materials at the nanometer scale profiting from their highly increased interaction area.
Especially at metal/oxide interfaces, accounting for a majority of heterogeneous catalysts, the structure-function relationship has been studied intensively. High temperature, dry aerosol processes are common for building such composites. But the formation of key structural elements in such multi-component systems, depending on coagulation-order and solid-solid diffusion, is not fully understood yet.
Here, we present crystalline Pd encapsulated in silica nanoparticles produced in a single step flame spray pyrolysis process.[1] Nanometer scale transformation of this material to nanocrystalline Pd dispersed on the amorphous silica matrix was achieved at elevated temperatures. A physical model gives an understanding of the influence of temperature, matrix viscosity, particle sizes and concentrations on this transformation process. It enables morphology predictions both in nanocomposite formation processes at elevated temperature and during thermal evolution of multi-phase nanomaterials, determining their performance in e.g. catalysis or fuel cells.
[1] S. Bubenhofer et al., J. Phys. Chem. C, in press (2011) | PC1 19 |
| 16:00 | Controlled Chemical Synthesis and Potential Applications of Magnetic Nanoscale Materials Authors : Department of Advanced Materials and Nanotechnology College of Engineering, Peking University, Beijing 100871, China E-mail: hou@pku.edu.cn Affiliations : Resume : Synthesis of mondisperse magnetic nanocrystals with controlled shape and size has become tremendous interest in developing nanocrystal arrays for information storage, permanent magnet nanocomposite, catalysis and biomedical applications. Here we report the controlled synthesis of magnetic nanocrystals range from nanoparticles, nanocubes to nanorods and nanowires through high temperature organic solvent routes. We also discuss the potential applications of these magnetic nanoparticles. | PC1 20 |
| 16:00 | PbO-BaO-Na2O-Nb2O5-SiO2 Nanocomposite Dielectrics with High Breakdown Strength for High Voltage Capacitor Applications Authors : Qingmeng Zhang, Shirong Zhang, Jun Luo, Qun Tang, Dongfang Han and Jun Du General Research Institute for Nonferrous Metals, Beijing, 100088, China Affiliations : Resume : Nanocomposite dielectrics in 6PbO-4BaO-20Na2O-40Nb2O5-30SiO2 system were prepared via cast-quenching followed by controlled crystallization. X-ray diffraction studies reveal that Pb2Nb2O7, NaNbO3 and (Pb, Ba)Nb2O6 phases are formed from the as-quenched glass in temperature range from 700 ºC to 850 ºC. NaNbO3, Pb2Nb2O7 crystallizes at 700 ºC and then Pb2Nb2O7 disappears at 850 ºC, while (Pb, Ba)Nb2O6 are formed at 850 ºC. Microstructural observation shows that nanometer-sized crystal grains are randomly oriented with residual glass concentrated at grain boundaries. The dielectric constant of the sample annealed at different temperatures shows good frequency and electric field stability. The breakdown strength of the samples annealed at 850 ºC was investigated. The result shows that the breakdown strength is slightly decreased with the sample thickness increasing from 1mm to 4mm. The highest breakdown strength is 58 kV/mm at the thickness of 1mm, and the corresponding energy density reaches 2.96 J/cm3. | PC1 21 |
| 16:00 | Controlling role of pH on the incorporation of cobalt into α-Fe2O3 nanostructures during hydrothermal synthesis. Authors : Trevor P Almeida1, Michael W Fay2, Yanqiu Zhu3 and Paul D Brown1 1 Division of Materials, Mechanics and Structures, Department of Mechanical, Materials and Manufacturing Engineering, Faculty of Engineering; & 2 Nottingham Nanotechnology and Nanoscience Centre, University of Nottingham, University Park, Nottingham, NG7 2RD, UK. 3 College of Engineering, Mathematics and Physical Sciences, University of Exeter, Streatham Campus, Northcote House, Exeter, EX4 4QJ, UK. Affiliations : Resume : Bulk hematite (α-Fe2O3) is canted antiferromagnetic (weakly ferromagnetic) at room temperature, antiferromagnetic below the Morin transition temperature of ~ 262 K and paramagnetic above its Néel temperature of ~ 955 K. One-dimensional (1D) α-Fe2O3 nanorods (NRs) can exhibit much higher magnetic coercivities than their bulk isotropic counterpart because of the effect of shape anisotropy. Hydrothermal synthesis (HS) has been identified as an effective method for the preparation of α-Fe2O3 nanorods. It is suggested that doping α-Fe2O3 NRs with ferromagnetic cobalt can further improve the magnetic coercivity, although definitive evidence for the incorporation of cobalt into α-Fe2O3 is still required. In particular, it is recognised that pH control is key in the precipitation of cobalt and improved understanding of its role is needed for the effective doping of α-Fe2O3. In this context, we present a feasibility study on the prospects for incorporation of ferromagnetic cobalt into α-Fe2O3 nanostructures during HS. The combined complementary characterisation techniques of TEM, SAED, EDX analysis and XRD have allowed a process map to be constructed, providing useful insight into the controlling role of pH on the nucleation and growth of α-Fe2O3, Co3O4 and CoFe2O4 nanostructures in the presence of FeCl3, CoCl2 and phosphate surfactant. | PC1 22 |
| 16:00 | Multi-step hydrothermal synthesis of Ni-doped α-Fe2O3 nanorods. Authors : Trevor P Almeida1, Michael W Fay2, Yanqiu Zhu3 and Paul D Brown1 1 Division of Materials, Mechanics and Structures, Department of Mechanical, Materials and Manufacturing Engineering, Faculty of Engineering; & 2 Nottingham Nanotechnology and Nanoscience Centre, University of Nottingham, University Park, Nottingham, NG7 2RD, UK. 3 College of Engineering, Mathematics and Physical Sciences, University of Exeter, Streatham Campus, Northcote House, Exeter, EX4 4QJ, UK. Affiliations : Resume : One-dimensional (1D) canted antiferromagnetic hematite (α-Fe2O3) nanorods (NRs) can exhibit much higher coercivities than their isotropic bulk counterpart because of the effect of shape anisotropy. Hydrothermal synthesis (HS) has been identified as an effective method for the production of α-Fe2O3 NRs. Aqueous FeCl3 solution is well established as a simple precursor for the formation of α-Fe2O3 nanoparticles (NPs), via an intermediate -FeOOH phase, and small additions of phosphate anions have been shown to mediate the anisotropic growth of α-Fe2O3, leading to the development of acicular NRs through the oriented attachment (OA) of primary α-Fe2O3 NPs. It is suggested that the doping of α-Fe2O3 NRs with ferromagnetic nickel can improve the magnetic coercivity. However, the precipitation of nickel and 1D α-Fe2O3 growth occur at significantly different pH values. Hence, a multi-step growth process as a function of pH is considered essential for the nickel doping of α-Fe2O3 NRs. In this context, an investigation of the doping of primary α-Fe2O3 NPs with nickel (at pH ~ 8), prior to their OA into α-Fe2O3 NRs, mediated by a phosphate surfactant (at pH < 2), is presented. The combined complementary characterisation techniques of conventional TEM, SAED, EDX, EELS, FTIR, XPS and XRD provide valuable insight into the formation mechanisms of HS nickel-doped α-Fe2O3 NRs. | PC1 23 |
| 16:00 | Processing and luminescence properties of core-shell SiO2@Er3+,Yb3+:Lu2O3 particles Authors : E. W. Barrera, M. C. Pujol, J. J. Carvajal, X. Mateos, M. Aguiló, and F. Díaz Física i Cristal.lografia de Materials i Nanomaterials (FiCMA-FiCNA-EMAS), Universitat Rovira I Virgili (URV) C. Sescelades, c/ Marcel.lí Domingo, s/n, E-43007 Tarragona, Spain C. Cascales Instituto de Ciencia de Materiales de Madrid, CSIC. Calle Sor Juana Inés de la Cruz,Cantoblanco, E-28049 Madrid, Spain Affiliations : Resume : In the last years nanostructured materials in form of core-shell particles has become a growing interest due the possibility to tailor their physical properties. One of the compounds more used as core is the amorphous silica, because the size and morphology could be controlled with reliability by the Stöber method. For layer deposition, the Pechini method offers homogeneous mixing of the starting materials, good control of stoichiometry, fine particle size and uniform morphology. Also, the lutetium oxide has been receiving growing interest recently due its favorable properties, such as high melting point, phase stability, low thermal expansion, high thermal conductivity, chemical stability and relative low phonon energy (about 600 cm-1), which is helpful for the enhancement of upconversion process. Core-shell SiO2@Er3+,Yb3+:Lu2O3 particles were obtained by a modified Pechini method using commercial silica microspheres. X-ray powder diffraction pattern, showing the overlapping of the cubic phase of sesquioxides and the amorphous phase of SiO2. High resolution TEM micrographs show core-shell nanostructures obtained from chloride and nitrate salts. The shell is composed by nanoparticles with ~5 nm in size; all of them are bonded on the surface of the silica microspheres forming layers and short necklace structures. Red and green emissions of Er3+ were observed under 514 nm and 633 nm laser excitation, respectively. | PC1 24 |
| 16:00 | Fabrication of Aligned Pairs of Gold Nanorodss in Silica Glass by Ion Irradiation Authors : Koichi Awazu, Xiaomin Wang, National Institute of Advanced Science and Technology, Japan, Tetsuo Komatsubara University of Tsukuba, Japan Shin’ichi Warisawa, Sunao Ishihara The University of Tokyo, Japan Affiliations : Resume : Pairs of gold nanodisks 40 or 70 nm in diameter were fabricated in silica glass as following process. The silica substrate was spin-coated with resist. Nanoscale patterns were drawn by electron-beam lithography. Subsequent development produced pairs of nanoscale holes in the resist. The substrate was deposited with Au in an evaporator. Next, the resist was removed to leave pairs of Au nanodisks on the substrate. The Au nanodisk pairs were then embedded in silica by depositing a second layer of silica. On irradiation by 110-MeV Br10+ ions, Au nanodisks of diameter 40 nm in silica were elongated to form aligned Au nanorods to the direction of ion beam incident direction. Aspect ratio of elongated nanorods increases with the fluence and flux density of ion irradiation. In contrast, Au nanodisks of diameter 70 nm in silica were not elongated. Based on simulation with thermal conductivity, we assume that both the 40-nm-diameter Au nanoparticles and surrounding silica were melted during ion bombardment, whereas in the case of the 70-nm nanoparticles, neither the nanoparticles nor the silica surroundings were melted during irradiation. It has been reported that the rapid thermal expansion of the ion track results in large shear stresses in the heated region. As a result, the compressive radial stress increases and the compressive axial stress decreases during viscous flow. The effects of the stresses and thermal spike combine to induce elongation of the Au nanoparticles. We will use this method to produce new plasmonic optical devices. | PC1 25 |
| 16:00 | Charge transport in graded composite films Authors : Rudolf Hrach (1,2), Stanislav Novák (2), Martin Švec (2), Věra Hrachová (1) (1) Department of Surface and Plasma Science, Faculty of Mathematics and Physics, Charles University, V Holešovičkách 2, 180 00 Prague 8, Czech Republic (2) Department of Physics, Faculty of Science, J. E. Purkinje University, České mládeže 8, 400 96 Ústí nad Labem, Czech Republic Affiliations : Resume : Composite films consisting of metal particles embedded into dielectric matrix have interesting physical properties determined by their structure. One of the important physical characteristics of the films is their electrical conductivity; the composite films behave like dielectrics or conductors depending on the concentration of the metal fraction. The most interesting features can be observed near a percolation threshold where the mechanism of charge transport is changing and the electrical conductance varies profoundly. The current paths form channels which lead to the so-called fuzzy clusters below the percolation threshold while above this threshold they are changing into standard ohmically conducting percolation paths.
Most of various technologies for nanocomposite films preparation result in the homogeneous structures where the transport mechanism is constant over the whole sample. Some methods of film preparation, however, lead to films with graded filling factor of metal fraction. The intensity of electric transport depends on film thickness and even the mechanism of charge transport can vary in these films. In order to investigate this phenomenon in detail, a computer experiment was prepared where the film structure was characterized by the algorithms of mathematical morphology and the charge transport was analysed by the kinetic Monte Carlo method. The main reason for this study was to find the correlation between films morphology and their electrical conductivity | PC1 26 |
| 16:00 | Shock Induced Reaction of Ni/Al Nanopowder Mixture Authors : C.M.Meng, J.J.Wei and Q.Y.Chen Key Laboratory of Shock Wave and Detonation Physics, Institute of Fluid Physics, Chinese Academy of Engineering Physics, Mianyang, 621900, China Institute of Atomic and Molecular Physics, Sichuan University, Chengdu, 610064, China Affiliations : Resume : Nanopowder Ni/Al mixture (mixed in Al:Ni=2:1 stoichiometry) was shock compressed by employing single and two-stage light gas gun. The particle size of Al and Ni are 100-200nm and 50-70nm respectively, morphologies of Al and Ni are sphere like either. The recovered product was characterized by XRD and SEM analysis. According to the XRD spectrum, the mixed powder undergo complete reaction under shock compression, main product consist of Ni2Al3, NiAl and corundum structure Al2O3 compound. Grain size of Ni-Al compound is less than 100nm and the ratio of Ni2Al3 decreased obviously at high shock pressure. The corundum crystal size is 400-500nm according to the SEM observation. The results of shock recovery experiments and analysis shows that the threshold pressure for reaction of nano size powder Ni/Al mixture is much lower than that of micro size powder. | PC1 27 |
| 16:00 | TRANSITION-KINETICS PHASE OF CRYSTALLIZATION BY ANNEALING OF AMORPHOUS SiCx:H INTRINSIC AND PHOSPHORUS-DOPED LAYERS Authors : I. Torres*1,2, F. Fonthal1,2, J. Pallarès3, J. Ferre-Borrull3 and L.F. Marsal3 1Grupo LOGOS, Departamento de EEST, Facultad de Ingeniería y Arquitectura, Universidad de Pamplona, Km 1 Via a Bucaramanga, Pamplona (N/S), Colombia. ivaldo.torres@unipamplona.edu.co. 2Advanced Materials for Micro and Nanotechnology Group - IMAMNT, Departamento de Automática y Electrónica, Universidad Autónoma de Occidente, Calle 25 No. 115-85, Cali, Colombia. 3Departament d’Engenyeria Electrònica, Elèctrica i Automàtica, Universitat Rovira i Virgili, Avda. Països Catalans, 26, 43007 Tarragona, Spain. Affiliations : Resume : The characterization of the annealed structures indicates that the a-SiCx:H layers are partially recrystallized during the annealing process forming Si-nanocrystals embedded in the amorphous film. In this process the transition-kinetics phase involve two steps where the activation energy and growth are required. To better understand this process and obtain the change of amorphous to crystalline in the transition-kinetics phase of the layers of a-SiCx:H intrinsic and phosphor-doped in-situ measures by X-Ray Diffraction (XRD) equipment with camera temperature at 900 degrees Celsius were used. Both intrinsic and phosphor-doped a-SiCx:H were deposited on a c-Si substrate p-type of 300um-thick with a cylindrical parallel plate PECVD reactor. Fitting in with the Avrami-Mehl-Johnson Theory for random nucleation and growth of crystallites of the a-SiCx:H layers, the energies of activation and crystallization of both layers, the nucleation time and the growth time were obtained. The formation of Si-nanocrystals affects the optical properties of the a-SiCx:H/c-Si samples. From the fitting of the FTIR transmission spectra and absorption indices of the intrinsic and phosphorus-doped a-SiCx:H layers have been calculated in the range of 1500-9000 cm-1 | PC1 28 |
| 16:00 | Time resolved in situ UV-vis absorption spectroscopy on growing ZnO quantum dots: Correlation to steady state fluorescence and x-ray diffraction measurements Authors : T. Jesper Jacobsson & Tomas Edvinsson Dept. of Materials Chemistry, Uppsala Univ., Box 538, 75121 Uppsala, Sweden Email: jesper.jacobsson@mkem.uu.se Affiliations : Resume : ZnO nanoparticles constitute a convenient model system for fundamental studies as well as having many possible technical applications in for example sensors and in the field of catalysis.
ZnO quantum dots in the size range 2.5–7 nm have been synthesized and analyzed in detail. Time resolved in situ UV-vis absorption measurements were used to monitor the growth of these particles in solution by correlating the optical band gap to particle size given from XRD measurements. The particles formed were isotropic in shape, but small initial deviations gives indications of a transition from thermodynamic to kinetically controlled growth for particles around 4 nm in diameter. Based on this, behaviour and mechanisms for the particle growth are discussed.
The fluorescence dependence on particle size was investigated by combining fluorescence and UV-Vis measurements on growing particles. This showed the importance of surface states and revealed that the positions of the fluorescence trap states are mobile towards the conduction- and valence band. A broadening of the trap states was also found and a surface dependent mechanism of the trap state shift and broadening is proposed. | PC1 30 |
| 16:00 | Size Dependent Luminescence of Dye Doped Nanorods Obtained in Polymer Membranes Authors : Monica Enculescu*, Christina Trautmann** *National Institute of Materials Physics, PO Box MG-7, 77125, Magurele-Bucharest, Romania **GSI, Helmholtz Centre, Planckstr. 1, D-64291 Darmstadt, Germany Affiliations : Resume : Studies regarding solid-state dye-doped materials are mostly restricted to polymers or glasses. Researches for crystalline dye-doped nanosized materials are focused on dye-doped polymers/gels coated semiconductors or metals. Ultra miniaturizing a material that combines the nonlinear properties of a second harmonic generating crystal with the luminescence of a lasing dye would be an attractive alternative.
The template method that produces nano-objects in polymer membranes containing pores obtained by heavy ion irradiation and subsequent chemical etching is a consecrated approach for obtaining nano-scaled objects of metals, semiconductors or insulators. Luminescent dye-doped nanorods of potassium acid phthalate (KAP) doped with rhodamine 6G (Rh 6G) were grown using the template assisted crystallization. Thus, pores in the range of hundreds of nanometers to tens of microns were obtained in polycarbonate (PC) foils. The nanostructures obtained by filling the pores were characterized using scanning electron microscopy, X-ray diffraction analysis, absorption spectroscopy and photoluminescence studies. The luminescence of the dye-doped rods presents a shift towards red when the diameter of the structures is decreasing. The shift is due to the increasing of dye concentration in doped rods grown inside the membrane’s pores. Moreover, the luminescence due to the Rh 6G presence in the dye doped nano and microrods is up-converted due to the second harmonic generating properties of KAP. | PC1 31 |
| 16:00 | Generation and self-organization of bimetallic Pd/Au nanoparticles on SiO2 by sequential sputtering depositions and annealing processes Authors : F. Ruffino, E. F. Pecora, M. G. Grimaldi Dipartimento di Fisica e Astronomia and CNR-IMM MATIS, Università di Catania, via S. Sofia 64, I-95123 Catania, Italy Affiliations : Resume : Nanoparticles (NPs) are key mainstays of the nanotechnology revolution. They are systems whose chemical and physical properties are strongly determined by the structural ones (size, shape). So, the physical/chemical response of NPs are wide-range tunable by the manipulation of their structural properties. Bimetallic NPs have important applications in various technological domains such as in heterogeneous catalysis, where their catalytic activity is dictated by their size.
In this work we report on the preparation and morphology manipulation of PdAu bimetallic NPs on SiO2. We prepared PdAu NPs on SiO2 by sequential sputtering of Pd and Au. By the atomic force and scanning electron microscopies we studied the growth mechanisms of the NPs in various conditions: 1) fixing the amount of Pd, the evolution of the morphology of the NPs as a function of the amount of Au was studied; this evolution was analyzed within the theoretical frameworks of the interrupted coalescence model and dynamic scaling theory of growing interfaces allowing the evaluation of the critical radius Rc for the coalescence, of the dynamic scaling and growth exponents; 2) fixing the amount of Pd and Au, the evolution of the morphology of the NPs as a function of annealing processes in the 973-1173K temperature and 2400-6000s time ranges was studied; this evolution was analyzed within the framework of the surface diffusion limited ripening allowing the evaluation of activation energy for the diffusion process. | PC1 32 |
| 16:00 | Soft magnetic FeHfN/SiNx multilayered films in power inductors Authors : Yu-Ming Kuo and Jenq-Gong Duh* Department of Material Science and Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan Affiliations : Resume : Nowadays, wireless communication products have been primarily developed towards the miniaturization involving a small size and a light weight. However, the conventional DC-DC converters occupy a quite large volume in cell phones, and to decrease the size of DC-DC converters, the power inductors require to be further miniaturized. Besides, from the viewpoint of application, the saturated current of inductors should be as high as possible to increase the performance of DC-DC converters. Thus, high inductance (L) and saturated current (Isat) are necessary to satisfy the demands for miniaturization. In this work, to integrate the FeHfN/SiNx multilayered films with the power inductors is exploited to improve the device properties, aiming to obtain suitable L and high Isat for DC-DC converter applications.
In this study, the nitrogen reactive sputtering method was used to deposit FeHfN/SiNx multilayered films on the Al2O3 substrates. The inductance (L) increases with stacking layers of multilayered films. The L enhances around 6 % from 0.275 (3 layers) to 0.291 μH (7 layers) at 0.5-1 MHz. Although the FeHfN single layer films possess the higher L, its Isat (< 1 A) is too low to be applied. By employing the multilayered coating, Isat is significantly enhanced as compared to that of FeHfN single layer films. With the optimum configuration of a seven-layer structure [FeHfN (700 nm)/SiNx (10 nm)]7, suitable inductance (L = 0.291 μH) and high saturated current (Isat > 2 A ) were obtained. | PC1 33 |
| 16:00 | ELECTRONIC PROPERTIES OF GOLD NANOCLUSTERS INVESTIGATED BY REELS Authors : P.V. Borisyuk, V.D. Borman, M.A. Pushkin, V.N. Tronin, V.I. Troyan National Research Nuclear University “MEPhI” Affiliations : Resume : Reflected-electron energy-loss spectroscopy (REELS) is known to be the effective tool for the investigation of the electronic excitations and dielectric response in solids. The technique seems also to be promising for the study of the electronic structure of nanoclusters. However, there is still a lack of the published results of such experiments.
The present paper reports the experimental results of the size-dependent electronic properties of gold nanoclusters investigated by REELS. The ensembles of Au nanoclusters pulsed laser deposited on graphite HOPG(0001) and SiO2 substrates were investigated in situ by REELS with their size (1-10 nm) controlled by STM and TEM. Energy-loss spectra of Au nanoclusters show peaks resulted from the excitations of surface and bulk plasmons as well as inter-band transitions. The position and intensity of the given peaks are plotted as functions of clusters size. The origin of the observed shifts is discussed with comparison to the data of optical absorption and photoelectron spectroscopies. The obtained data allow the analysis of the size behavior of the dielectric response of Au nanoclusters. | PC1 34 |
| 16:00 | Diffraction Properties of the Nanostructured Surface Authors : V.M. Katerynchuk, Z.D. Kovalyuk, A.I. Savchuk* Chernivtsi Department of the I.M. Frantsevych Institute of Materials Science Problems, The National Academy of Sciences of Ukraine, 5, Iryna Vilde St., 58001, Chernivtsi, Ukraine E-mail: chimsp@ukrpost.ua *Department of Semiconductors Physics and Nanostructures, Chernivtsi National University, 2, Kotsyubynsky St., 58012, Chernivtsi, Ukraine Affiliations : Resume : The photosensitive In2O3-p-InSe heterostructures in which the In2O3 frontal layer has a nanostructured surface were investigated. The photoresponse spectra of such heterostructures are found to be essentially dependent on surface topology of the oxide. The obtained results indicate that the In2O3 oxide is not only the active component of the structure but also acts as a diffraction cellular element.
The oxide surface topology was investigated by means of the atomic-force microscope technique. It was established that the surface topology is caused by the technological conditions of growing In2O3 oxides. At different conditions of oxidation the sample surfaces had contained nanoformations preferably in the form of nanoneedles. Their location has both a disordered and ordered character. The sizes, form and density of the nanoneedles are different, too.
A dimensional optical effect in the oxide was found to be due to the anisotropic light absorption in InSe. The higher deviation of incident light from its normal direction due to a nanostructured surface the higher variation in the generation of carriers in the semiconductor is. These changes consist in the energy broadening of the heterostructure photoresponse spectrum as well in peculiarities of the excitonic line. The higher density and ordering of the nanoneedles on the oxide surface is the higher long-wave shift and more intensive excitonic peak in spectrum take place. | PC1 35 |
| 16:00 | Synthesis and luminescent characterization of Sr2SiO4:Eu2+ nano powders Authors : Jun Seong Lee, Young Jin Kim Department of Materials Science and Engineering, Kyonggi University, Suwon 443-760, Korea Affiliations : Resume : Europium ions doped strontium orthosilicate, Sr2SiO4:Eu2+, is one of the most popular and commercial green/yellow phosphors. Sr2SiO4 has polymorphs of β- (monoclinic) and α’-form (orthorhombic), whose transformation is displacive and easily completed by a simple rearrangement of atoms without breaking coordination bonds. In this study, the structural and luminescent properties of Sr2SiO4:Eu2+ nano powders prepared by a co-precipitation method were investigated. Strontium nitrate (Sr(NO3)2), 3-aminopropyltriethoxysilane (APTES), and europium nitrate hydrate (Eu(NO3)3•xH2O) were used as starting materials. The as-prepared nano powders were heat-treated at 1100 – 1500 oC under the reduction atmosphere. β- and/or α’-phase Sr2SiO4:Eu2+ powders were obtained, and the results suggested that the α’ ↔ β phase transition depended on the annealing and precipitation conditions. Two excitation bands at around 320 and 370 nm were observed due to Sr(I) and Sr(II) sites, leading to two emission bands whose peak positions and emission intensities were affected by the structure and size of powders. | PC1 36 |
| 16:00 | Surface studies of coarse-grained and nanostructured titanium implants Authors : D.M. Korotin1, S. Bartkowski2, E.Z. Kurmaev2, M. Neumann1, E.B. Yakushina3, R.Z. Valiev3, and S.O. Cholakh4 2Institute of Metal Physics, Russian Academy of Sciences-Ural Division, 620990 Yekaterinburg, Russia 2Faculty of Physics, University of Osnabruck, 49069 Osnabruck, Germany 3Institute of Physics of Advanced Materials, Ufa State Aviation Technical University, 12 K. Marx str., Ufa 450000, Russia 4Ural Federal University, 620002 Yekaterinburg, Russia Affiliations : Resume : The results of XPS measurements of commercially pure titanium (cp-Ti) before and after chemical treatment are presented. We have measured XPS spectra of core levels (Ti 2p, O 1s, C 1s, F 1s) and valence bands of coarse-grained and nanostructured cp-Ti before and after standard acid pretreatment accepted in dentistry (in 1% HF and 40% HF during 1 min). It is found that acid treatment of cp-Ti reduces the content of hydrocarbons to 1.5 – 2.6 times increasing the surface energy and bio-acceptability of Ti-implants. For each set of XPS measurements ion etching (with Ar+ ions) was performed step by step with interval of few minutes (from 1min to 84 min) and by such a way a full information about the surface and near the surface layers of cp-Ti before and after chemical treatment is obtained. XPS Ti 2p-spectra show that the surface of cp-Ti is covered by thick TiO2 (Ti4+) oxide layer. The chemical treatment changes near the surface composition of oxide layers increasing the contribution of TiO (Ti2+). In accordance with recent calculation of electronic structure of Ti-substituted hydroxyapatite Ca10(PO4)6(OH)2 [1] which is the main component of tooth enamel and bones, the Ti2+ substitution of Ca2+ is thermodynamically favored and provides excellent biocompatibility of chemically treated cp-Ti.
References:
1. S. Yin and D.E. Ellis, First principles investigation of Ti-substituted hydroxyapatite electronic structure, Phys. Chem. Chem. Phys. 12 (2010) 156.
We acknowledge support of the Russian Science Foundation for Basic Research (Project 11-02-00022), the Natural Sciences and Engineering Research Council of Canada (NSERF) and the Canada Research Chair Program. | PC1 37 |
| 16:00 | Anomalous magnetic behavior of Sm0.8Ca0.2MnO3 nanoparticles Authors : D. Mogilyansky,1 I. Fita,2, 3 V. Markovich,4 A. Wisniewski,2 R. Puzniak,2 and G. Gorodetsky4 1Institute of Applied Research, Ben-Gurion University of the Negev, 84105 Beer-Sheva, Israel 2Institute of Physics, Polish Academy of Sciences, Aleja Lotnikow 32/46, 02-668 Warsaw, Poland 3Donetsk Institute for Physics & Technology, National Academy of Sciences, 83114 Donetsk, Ukraine 4Department of Physics, Ben-Gurion University of the Negev, 84105 Beer-Sheva, Israel Affiliations : Resume : Magnetic properties of compacted Sm0.8Ca0.2MnO3 manganite nanoparticle samples with average particle size of 23-100 nm, prepared by the glycine-nitrate method, have been investigated. The relative volume of the ferromagnetic phase decreases with decreasing particle size. It was found that the spontaneous magnetization of the smallest particles (23 nm) approaches a value of 28 % in respect to the value for bulk.1 The field cooled (MFC) and zero filed cooled (MZFC) magnetization curves bifurcate just below the Curie temperature which is significantly smaller of that for bulk (TC 85 K) 1 and varies only slightly (TC 55 – 60 K) for all nanoparticles studied The field dependence of ZFC magnetization peak follows de Almeida-Thouless line.2 Remanent magnetization exhibits slow relaxation below TC. All these features indicate a behavior characteristic for spin-glasses (SG). Measurements of ac-susceptibility at temperatures 5 – 300 K and in frequency range f = 10 Hz – 10 kHz show for all nanoparticles studied a sharp peak in both the real and imaginary part of the susceptibility in the vicinity of TC attributed to the Hopkinson effect and a second small peak tentatively associated with AFM ordering. Though for smaller particles both peaks depend on frequency no shift to high T-side with increasing f as it characteristic for SG systems, was observed. The absence of any temperature shift of the peak position with frequency is in sharp contrast with the pronounced superspin-glass characteristics observed recently in La0.8Ca0.2MnO3 nanoparticles.3
.
1. C. Martin et al., Phys. Rev. B 60, 12191 (1999).
2. J. R. L. de Almeida and D. J. Thouless, J. Phys. A 11, 983 (1978).
3. V. Markovich et al., Phys. Rev. B 81, 134440 (2010). | PC1 38 |
| 16:00 | Tuning of Surface Plasmon Resonance in Ultrathin Gold Films by Post-growth Thermal Processing Authors : N. L. Dmitruk, O. S. Kondratenko, V. R. Romanyuk Institute for Physics of Semiconductors NAS of Ukraine, Kyiv, Ukraine Affiliations : Resume : Thin semitransparent solid/island metal films are important element of nanophotonic devices based on surface plasmon polaritons excitations. Stability of films, optical and other parameters strongly depend on film fabrication technology and post-fabrication treatment. In this work we report our results of systematic study of size effects in ultrathin (cluster) metal (gold) films and their transformation by thermal annealing (especially effect of these changes on surface plasmon resonance).
Gold films with thickness from 8 to 80 nm were thermally evaporated in vacuum on the nonheated glass substrates. Structure and morphology of films were examined with TEM and AFM techniques. Optical behavior of these gold films were investigated with transmittance/reflectance spectroscopy of polarized light (350-1100 nm) at various angles of incidence, by monochromatic (632.8 nm) ellipsometry in standard reflection mode and in the Kretschmann geometry of attenuated total reflection mode (polaritonic ellipsometry).
Thin films were subjected to vacuum annealing at temperatures 100-400C. Relations between optical parameters and annealing temperatures are considered in respect to structural changes in grained gold nanofilms. Optical behavior of produced metal nanofilms has been described by effective medium approximation taking into account both the particles shape effect and the size classic and topology effect. The optimal annealing conditions for obtaining the maximal quality coefficient of plasmon resonance in metal have been ascertained which is very important for applications in polaritonic optoelectronics / photovoltaics and sensorics. | PC1 39 |
| 16:00 | The dependence of the up-conversion properties of NaYF4:Yb3+,Er3+ nano powders on the structure and particle size Authors : Seok Hun Kwon, Jun Seong Lee, Young Jin Kim, Department of Materials Science and Engineering, Kyonggi University, Suwon 443-760, Korea Affiliations : Resume : The rare-earth ions doped NaYF4 powders are well recognized as up-conversion phosphors. The co-doping of the Yb3+ and Er3+ ions generates high up-conversion emissions by infrared lights due to the efficient energy transfer from Yb3+ to Er3+. In this works, NaYF4:Yb3+,Er3+ nano powders were synthesized by a solvothermal method, and the correlation between the emission and structural properties was studied. The precursors were prepared with various compositions of reactants, and then NaYF4:Yb3+,Er3+ nano powders were achieved in a Teflon-lined autoclave at various parameters such as the temperature and time. The preparation conditions caused the evolution in structure and size, affecting the luminescent properties. The powders synthesized at the high temperature around 200 oC showed a hexagonal phase dominantly, whereas cubic powders were preferentially obtained at the low temperature. The luminescent properties, which showed green and/or red emissions under 980 nm infrared excitation, strongly depended not only on the phase of NaYF4, but also on the particle size that varied from micro- to nano-scale. | PC1 40 |
| 16:00 | Microstructure of functionalizated graphite Authors : I. V. Ovsiienko, L. L. Vovchenko, L. Yu. Matzui, O. I. Brusilovetz, M. I. Zakharenko, Yu. S. Perets Kyiv National Taras Shevchenko University Affiliations : Resume : The work is devoted to questions of interrelations between methods of functionalization and structure of the functionalizated thermoexfoliated graphite (TEG). Functionalization of TEG was carried out with using of inorganic (KMnO4 solution in the sulfuric acid, mixture of sulfuric and nitric acids) and organic (ethanol, toluene, acetone and chloroform) reagents and during different time of re-dispersion in the magnetic stirrer. Quantitative and qualitative composition of functional groups on the TEG particles surface was determinated by infrared spectroscopy method. The microstructure of functionalizated TEG was investigated by X-ray diffraction, optical and electron microscopy methods. It is revealed from detailed studies of structural and phase composition that all specimens of functionalizated TEG are heterosystems composed of at least two carbon phases with different crystalline parameters. The size distribution of functionalizated with using different reagents TEG particles is estimated. TEG functionalization results in destruction of initial TEG structure and reduction of TEG particles size under some nanometers. It is shown that such structure “deterioration” first of all concerned with action of functionalizating reagent that is strong oxidant. The action of mechanical treatment essentially doesn’t affect on the structure of functionalizated TEG. | PC1 41 |
| 16:00 | Spontaneous formation of highly dispersed spheroidal metal silver nanoparticles in surfactant-free N,N-dimethylacetamide Authors : Luiz P. da Costa, André Luiz B. Formiga, Fernando A. Sigoli and Italo O. Mazali *. Institute of Chemistry - University of Campinas - UNICAMP, 13083-970, Campinas-SP, Brazil. Affiliations : Resume : Metal Silver nanoparticles (AgNPs) are widely used in microelectronics, photoelectron materials, electronic conduction materials, as catalysts, etc., due to their unique electrical, magnetic and other physicochemical properties1. The present work describes a simple method for preparing highly dispersed spheroidal metal silver nanoparticles in surfactant-free N,N-dimethylacetamide (DMA) solution. Using optimized geometries for N,N-dimethylacetamide and N,N-dimethyformamide, vertical ionization energies and electron affinities were calculated by means of the UHF/DFT calculations of cations and anions, respectively. The optical properties, shape and size of the silver nanoparticles obtained in DMA after different time of reaction were characterized using UV–Vis absorption spectroscopy and transmission electron microscopy. The silver nanoparticles are spheroidal and highly dispersed with no signs of particle agglomeration, indicating a stabilization of particles due to their chemical interaction with N,N-dimethylacetamide. The average size of the metal silver nanoparticles is smaller than that obtained by the well established procedure using N,N-dimethyformamide2. This simple methodology may be used for further studies about the SERS effect and other optical properties that depend on SPR bands of silver nanoparticles. | PC1 42 |
| 16:00 | Morphology control of metal silver nanoparticles in lamellar host materials Authors : Luiz P. da Costa, Fernando J. Quites, Heloise O. Pastore, Fernando A. Sigoli and Italo O. Mazali*. Institute of Chemistry - University of Campinas - UNICAMP, 13083-970, Campinas-SP, Brazil. Affiliations : Resume : In the past decade, many efforts have been paid in shaping the metal nanostructures, because the physical and chemical properties are highly dependent on their morphologies [1]. Several methodologies are available in the literature dealing with the preparation of silver and gold nanoparticles with different particle size and shapes [2]. This work reports a facile and novel route for the preparation of silver nanoparticles (AgNPs) with controlled morphology, using lamellar host materials, such as (i) cetyltrimethylammonium bromide-expanded Na -magadiite and (ii) aluminophosphate with kanemite-type structure (AlPO-kan). The UV-Vis spectra of the Na -magadiite silver-based nanocomposite present bands characteristic of silver nanoplates and the spectra of the hybrids based on Ag-AlPO-kan show an absorption band attributed to the plasmon resonance of silver nanospheres. Transmission electron microscopy (TEM) agrees very well with the results of XRD and UV-Vis absorption indicating the formation of AgNPs with different morphologies that are controlled by the lamellar structure of the host materials. The Na -magadiite has a strong interaction between the silicate layers leading to the growth of silver nanoplates and a small increase of the interlamelar space (XRD). In other hand, AlPO-kan has a weaker interaction between the layers allowing the preparation of sphere-like morphology increasing the interlamelar space. Therefore, the host materials have an important role on the morphology of the silver NPs that is controlled by the strength of the chemical interaction between the layers of the lamellar host materials. | PC1 43 |
| 16:00 | Magnetic nanoparticles of iron oxides: the influence of experimental parameters Authors : Fabiana C. A. Corbi, Fernando A. Sigoli, and Italo O. Mazali. Institute of Chemistry - University of Campinas - UNICAMP, 13083-970, Campinas-SP, Brazil. Affiliations : Resume : Iron oxide magnetic nanoparticles (NP) have been considered for technological applications due to their inherent magnetic properties, surface area and surface charge. Because of its biological compatibility and chemical stability, magnetite has also been considered for the development of new targeted drug delivery systems. Different methods have been developed for the preparation of iron oxides. In this work, iron oxide NP with different crystalline phases were synthesized by solvothermal reaction using the following precursors: Fe(NO3)3, FeCl3, ethyleneglycol as solvent and polyethylene glycol (PEG) as surfactant. According to the XRD and FTIR results, when iron chloride is used, NP of magnetite phase are obtained. On the other hand, hematite nanoparticles are prepared when iron nitrate is used. Morphological analysis of the NP, carried out by SEM-FEG, revealed that well dispersed spherical nanoparticles are obtained when iron chloride is used regardless the presence of the PEG. When iron nitrate is used in the absence of PEG, the morphology of nanoparticles is not well defined and the system is surrounded by a gel, as described in the literature. However, a spherical morphology of NPs is observed in the presence of PEG. The presence of organic matter in the samples obtained using iron nitrate is confirmed by the TGA data. Therefore, the analysis of the experimetal parameters is essential to obtain the desired monodispersed magnetic nanoparticles with a specific phase. | PC1 44 |
| 16:00 | Semiconductor Nanocrystals with functional ligands Authors : Jessica Völker, S. Flessau, Alf Mews* University of Hamburg Affiliations : Resume : Due to their size dependent optical properties semiconductor nanocrystals have attracted considerable interest in the past decades. While the fluorescence wavelength strongly depends on particle size, the fluorescence intensity is mainly governed by their surface structure. For example, the attachment of thiol ligands leads to a decrease of fluorescence intensity for CdSe nanocrystals, whereas the emission intensity of CdTe nanocrystals is increased.
Herein we show that fluorescence quenching can be explained by charge transfer from the inorganic nanocrystals to the organic surface ligands. Results obtained from cyclic voltammetry are used to compare the energetic positions of the particles’ valence- and conduction bands levels with the ligands’ HOMO and LUMO levels. A functional crownether ligand is exploited for a controllable shift of the electrochemical potential by ion-complexation, which changes the fluorescence intensity of the nanocrystals in solution.1
Furthermore, the influence of thiols and crownether ligands on CdSe and CdTe core/shell nanoparticles with different shell materials and shell thicknesses is studied.
Confocal fluorescence spectroscopy on individual particles is carried out in order to characterize their fluorescence decay behaviour. Preliminary experiments on nanocrystals immobilized within microfluidic devices demonstrate the potential of in-situ PL measurements for sensing of molecules of ions in solution.
1 Ang. Chem Int. Ed., 2010, 49, 6865 | PC1 45 |
| 16:00 | Phase transitions in CdSe Quantum dots. Authors : Fehmida Kanodarwala 1 and Dr. John A. Stride 1,2 1 School of Chemistry, University of New South Wales. 2 Bragg Institute, Australian Nuclear Science and Technology Organisation. Affiliations : Resume : Quantum dots (QDs) are nanocrystalline semiconductors which exhibit extraordinary quantum confinement phenomenon [1] - which provides them with distinctly different optical, electronic, and magnetic properties from their bulk counterparts. These properties have enabled their application to many different technological areas including biological labelling and diagnostics [2], light-emitting diodes [3] and electroluminescent devices, photovoltaic devices, lasers, and even as single-electron transistors.
QDs have been fabricated employing a number of synthetic schemes ranging from molecular beam epitaxy [4] to wet-chemical colloidal synthesis.
Our aim is to synthesis high-quality CdSe nanocrystals through benchtop colloidal synthesis whilst analysing the effects of varying the reaction temperature, solvent and reaction time on the size, shape and crystallinity of the quantum dots.
The changes in reaction time induced the transition of the crystallite phases from cubic zinc-blende to hexagonal wurtzite and back again to cubic phase. We believe this is due to the rapid growth along the {111} facets of the cubic unit cell and then finally the other facets 'catch-up' to result in a particle with cubic symmetry once again.
The crystal phases were identified by employing powder X-ray diffraction, the results of which were in conformity with those deduced through high resolution transmission electron microscopy.
References:
[1] Dabbousi, B. O. et al. J. Phys. Chem. B 101, 9463 (1997).
[2] Dubertret et al.,Science, Vol. 298,Nov. 2002
[3] Lee, Chih-Wen; Yang, et al., J. Nanoscience and Nanotech., Vol. 9, No. 3, March 2009 , pp. 2076-2080.
[4] P. Petroff et al, Physics Today, May 2001 | PC1 46 |
| 16:00 | SYNTHESIS AND CHARACTERIZATION OF CdS NANOTUBES BY AMMONIA-FREE CHEMICAL BATH DEPOSITION IN ION-TRACK MEMBRANES Authors : N. PREDA1*, M. ENCULESCU1, E. MATEI1, M. E. TOIMIL-MOLARES2, I. ENCULESCU1 1National Institute of Materials Physics, Multifunctional Materials and Structures Laboratory, Bucharest-Magurele, P.O.Box MG-7, 77125, Romania 2Gesellschaft fur Schwerionenforschung, Planckstrasse 1, D-64291 Darmstadt, Germany Affiliations : Resume : In the recent years, due to their interesting optical and electronic properties, cadmium sulfide (CdS) nanostructures, such as nanoparticles, nanowires, nanotubes, etc. received a significant attention regarding their synthesis, characterization and applications in various areas.
CdS nanotubes were obtained by ammonia-free chemical bath deposition (CBD) using polycarbonate (PC) membranes as templates. This ammonia-free process is an already established green-technique being environmentally friendly reducing the ammonia release in the environment. The chemical synthesis consists in the growth of CdS nanotubes in the etched ion-track PC membranes, from the reaction between cadmium nitrate, thiourea and sodium citrate. The semiconductor nanostructures were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), optical absorption and photoluminescence. SEM images prove that the diameters of semiconductor tubes are between 300 nm and few microns and the lengths are up to tens of micrometers. The XRD patterns show that the nanostructures are of hexagonal phase with preferred (002) orientation. The optical studies reveal a band gap value of about ~ 2.75 eV (~ 450 nm) and a red luminescence at ~1.77 eV (700 nm).
It is expected that the present method can be easily extended to synthesis of similar II–VI semiconductor nanostructures.
ACKNOWLEDGEMENTS
This work was supported by CNCSIS-UEFISCSU, project number PNII-RU code 59/2010 (contract no. 18/28.07.2010). | PC1 47 |
| 16:00 | Size-dependent magnetic susceptibility of Si and SiGe nanowires Authors : A.A.Druzhinin (1), I.P. Ostrovskii (1), Yu.M. Khoverko (1), Iu.R.Kogut (1), S.I. Nichkalo (1), J.K.Warchulska (2) (1) Lviv Polytechnic National University, 1 Kotlarevsky Str., 79013 Lviv, Ukraine (2) International Laboratory of High Magnetic Fields and Low Temperatures, 95 Gajowicka Str., 53-421 Wroclaw, Poland Affiliations : Resume : In the present paper magnetic properties of heavily boron-doped Si and SiGe nanowires have been studied in the range of magnetic field (0,3 - 4,0) kOe in temperature range of 4,2 - 300 K. In particular, magnetization and magnetic susceptibility (MS) have been investigated. The results obtained in the temperature range of 77 - 300 K have shown several peculiarities: 1) a substantial paramagnetic contribution into magnetization and magnetic susceptibility; 2) non-linear dependence of magnetization on magnetic field; 3) dependence of magnetic susceptibility on the thickness of nanowire. These facts indicate in existence of magnetic ordering in nanowires. A hysteresis of magnetization at 4,2 K and substantial growth of magnetization (in several orders of magnitude) at T< 7 K have been observed, which confirm the above supposition. A discussion on possible reasons of the observed effects is presented. | PC1 48 |
| 16:00 | The effect of high pressure torsion on structural refinement and mechanical properties of an austenitic stainless steel Authors : Agnieszka Teresa Krawczynska 1, Malgorzata Lewandowska1, Reinhard Pippan2, Krzysztof Jan Kurzydlowski1 1 Warsaw University of Technology, Faculty of Materials Science and Engineering, Woloska 141,02-507 Warsaw, Poland 2Erich Schmid Institute of Materials Science, Jahnstra? 12, 8700 Leoben, Austria Affiliations : Resume : In the present study, the high pressure torsion (HPT) was used to refine the grain structure down to the nanometer scale in an austenitic stainless steel. The principles of HPT lay on torsional deformation under simultaneous high pressure of the specimen, which results in substantial reduction in the grain size.
Disks of the 316 LVM austenitic stainless steel of 10 mm in diameter were subjected to equivalent strains of 32 at RT, 90, 270 and 450°C under the pressure of 4 GPa. Furthermore, two-stage HPT processes, i.e. deformation at room temperature followed by deformation at 450°C, were performed. The resulting microstructures were investigated in TEM observations. The mechanical properties were measured in terms of the microhardness and in tensile tests. It was revealed that with the increase of temperature the microhardness increased. HPT performed at two-stage conditions (firstly at RT next at 450°C) gives similar values of microhardness to the ones obtained after deforming only at 450°C but performed to higher values of the overall equivalent strain The effect of high pressure torsion on structural refinement and mechanical properties of an austenitic stainless steel was quantitatively evaluated. | PC1 49 |
| 16:00 | SIZE EFFECT UNDER PHORETIC COATINGS PREPARATION Authors : I.Uvarova, O.Shchevchenko, I.Kud Frantsevych Institute for Problems of Materials Science of NAS of Ukraine, 3 Krzhyzhanovskoho str., Kyiv 03142, Ukraine Е-mail: uvarova@ipms.kiev.ua; Tel/fax 38044 424-2581 Affiliations : Resume : Current material science is focused on science-based selection of materials for coatings and production of nanostructured coatings characterized by higher level of properties. In order to attain high adhesion characteristics for phoretic coatings, two steps of deposition process have been studied taking into account the particle size of initial powders. First the process conditions in deposition of phoretic coatings, in particular the effect of the molybdenum disilicide particle size (micro- and nanosized powders) on the process of deposition onto a molybdenum substrate were studied. Then the character of consolidation process and the structure of sintered in vacuum coatings were studied. In the case of microsized powders, the consolidation process at 1650 oC was established to proceed via a liquid phase sintering mechanism, whereas nanosized powders consolidate via a solid phase sintering only. Herein no marked increase in the particle size was observed. The possibility of changing properties of phoretic coatings by using combination of different layers prepared by deposition of micro- and nanosized powders was studied. The influence of impurities and intermediate products on the consolidation process as well as the data of electron-microscopic and metallographic analyses, microhardness distribution along the coating depth, its dependence on the coating deposition conditions and heat treatment have been discussed. | PC1 50 |
| 16:00 | Influence of nanoclusters on lattice parameter of GaAs:(Mn,Ga)As granular layers Authors : J. Bak-Misiuk a, E. Dynowska a, P. Romanowski a, J. Z. Domagala a, P. Dluzewski a, J. Sadowski a,b, W. Caliebe c, A. Misiuk d a Institute of Physics PAS, al. Lotnikow 32/46, PL-02-668 Warsaw, Poland b MAX-Lab, Lund University P.O. Box. 118, S-22100 Lund, Sweden c HASYLAB at DESY, Notkestr. 85, D-22603 Hamburg, Germany d Instiute of Electron Technology, Al. Lotnikow 46, PL-02-668 Warsaw, Poland Affiliations : Resume : The granular GaAs:(Mn,Ga)As layers can be prepared by annealing of GaMnAs. At room temperature such materials exhibit, depending on the cluster size, a ferromagnetic or superparamagnetic behavior. X-ray diffraction and TEM were applied to study the structure of the GaAs:(Mn,Ga)As system as a function of Mn concentration and annealing temperature. The Ga1-xMnxAs (x=0.015-0.08) layers grown on the GaAs (001) substrate were studied, before and after annealing at 773 K or 873 K. The out–of–plane lattice parameter and tensile strain induced in the granular GaAs:(Mn,Ga)As layers after annealing depend on the dimensions and concentration of nanoinclusions. In the layers with low Mn concentration, annealed at 873 K, the formation of small (3-6 nm) cubic precipitates was preferred. For the samples with higher Mn concentration, hexagonal inclusions were formed already at 773 K, while annealing at 873 K caused a creation of a higher number of hexagonal nanoinclusions. An analysis of X-ray and TEM results leads to the conclusion that the cubic inclusions induce enlarged stress on the matrix unit cells in comparison to that of the hexagonal ones. An explanation of lattice strain introduced into the GaAs matrix is proposed. | PC1 51 |
| 16:00 | PECULIARITIES OF THE MoSi2-CrSi2 SOLID SOLUTION FORMATION DEPENDING ON THE CONDITIONS OF SOLID PHASE SYNTHESIS Authors : I.Kud, L.Likhoded, L.Yeremenko, D.Zyatkevich, I.Uvarova Frantsevych Institute for Problems of Materials Science of NAS of Ukraine, 3 Krzhyzhanovskoho str., Kyiv 03142, Ukraine Е-mail: uvarova@ipms.kiev.ua; Tel/fax (044) 424-2581 Affiliations : Resume : Materials and coatings oriented at operation in oxidizing media at high temperature are of great interest as heaters, sensors, protective multifunction coatings to be used over the temperature range 1000-1800 oC in chemical and related areas of industry as well as in aircraft and space engineering. Comparison of the products of solid phase interaction in the systems of traditional refractory materials and of their activated mixtures has been performed in this work. The difference in the kinetics of formation of silicide phases and solid solutions on their base was demonstrated on the example of the Mo-Cr-Si system through investigation of the kinetic regularities of the solid solution formation under intense mechanical treatment as well as solid phase interaction in vacuum of prior mechanically activated mixtures. During the investigation of mechanosynthesis of chromium and molybdenum disilicides solid solutions calculated for the composition Mo0,9Cr0,1Si2, it was established that the solid phase reaction proceeds without stages of formation of lower silicides. Since the interaction takes place in the low temperatures region, where the rate of chemical reaction exceeds the rate of the diffusion movement of the components, the mechanism of solid solution formation is kinetic. The best results were obtained in the case of using initial elements (Mo,Cr and Si) rather than prior prepared disilicides.
The regularities of the solid solution CrSi2-in-MoSi2 formation have been investigated for reaction mixtures composed of a prior mechanically synthesized precursor (solid solution of chromium in molybdenum) and activated silicon in the course of the solid-phase interaction in vacuum in the temperature range 400-1000 оС as well as for prior activated in a planetary mill powdered mixtures of the initial components, namely molybdenum, chromium and silicon. | PC1 52 |
| 16:00 | Vibration sensing using field emission from carbon nanotubes on silicon tip Authors : Yaser Abdi* , Azadeh Malekan Nanophysics Research Lab. , Department of Physics, University of Tehran, Tehran, Iran Affiliations : Resume : Field emission based cantilever sensor using carbon nanotubes on silicon tip was fabricated and frequency depended electrical response of the device to the mechanical vibration was investigated. Plasma enhanced chemical vapor deposition was used to grow carbon nanotubes (CNTs) on silicon made AFM tip. Field emission from nanotubes on silicon tip was realized for sensing the displacements and measuring the acceleration. Exponential dependence of the field emission current to the distance between the anode and the emitter leads to have high sensitive device. The variation of the emission current during mechanical vibration of the cantilever was measured. Experimental results show that the field emission from nanotubes increases by increasing the vibration frequency. In this work we have obtained the frequency limit for field emission based sensors. In other words, this work shows that how we can use the field emission mechanism for measuring the acceleration. In this work we have introduced a CNT based sensor for sensing the mechanical vibration in nanometer ranges. The fabricated device, due to a low distance between its electron emitters and the anode, works at low voltages with high emission current. Experimental results have been compared with a model based on Fowler-Nordheim theory of the field emission. Comparison shows a good agreement between the experimental data and the theoretical results. | PC1 54 |
| 16:00 | Phonon energy spectra and stationary elastic waves in carbon nanotubes Authors : V.O.Gubanov1, M.M.Biliy1, L.O.Komarova1, O.V.Rozhylo1, R.A.Poveda2. 1Kyiv National Taras Shevchenko University, Department of Physics, 64 Volodymyrs’ka str., 01601Kyiv, Ukraine 2Kam’yanets-Podil’s’kyy National Ivan Ogienko University, Department of Physics. Ogienko str., 61, Kam’yanets-Podil’s’kyy, 32300, Ukraine Affiliations : Resume : It is shown that the phonon excitations in points AK and AM of Brillouin zone of both metal and semiconducting nanotubes are classified with one-valued projective representations of projective class K5. Using the matrixes of irreducible projective representations of this projective class we have built the forms of phonon and stationary elastic waves in these structures and have obtained the compatibility relations which characterise the dispersion of vibrational states along nanotube axes.
The scheme of these compatibility relations, which coincide with compatibility relations in Г-А-direction of Brillouin zone for graphite crystals, is presented.
It is shown also, that the bands of second order Raman spectra of SWCNTs reflect the dispersion of vibrational excitations of graphene monosheet. | PC1 55 |
| 16:00 | Study of SERS Chemical Mechanisms using graphene/carbon allotropes hybrid structures Authors : Luisa D’Urso*, Giuseppe Forte*, Gabriele Messina*, Giuseppe Compagnini*, Orazio Puglisi* *Catania University Affiliations : Resume : Recent research activities have been focused the attention on the synthesis of novel nanomaterials obtained by the synergic interaction of nanostructures at different dimensionality and nature in order to obtain nanocomposite systems with advanced performances beyond those of the individual materials. Depending on their spatial organization, nanomaterials can be divided into categories of dimensionality zero (0D), one (1D) and two (2D). Fullerenes, polyynes and cumulenes, carbon nanotubes and graphene are carbon nanomaterials ranging from 0D to 2D that have attracted much attention due to their excellent properties, peculiars of the considered carbon allotrope.
Recently studies have been proposed graphene as substrate for Raman enhancement due to the electronic structure of graphene that can promote charge transfer phenomena.
In order to explore novel functional nanomaterials, we have produced hybrid carbon structures composed by graphene layers and carbon allotropes at different dimensionality. In comparison with pristine graphene samples, a remarkable change of the graphene electronic and phononic behaviour is observed after the interaction. The combination of carbon materials is realized coupling the mechanical exfoliation with the laser ablation in liquid technique. Raman and SERS spectroscopies together to the Density Functional Theory approach are employed to explain charge transfer phenomena in the produced carbon hybrid, inducing hole-doping in graphene layers. | PC1 56 |
| 16:00 | Bismuth flow effect on spectral reflectance of InAs/GaAs structure grown by MOVPE. Authors : I. Massoudi, M. M. Habchi, A. Rebey, B. El Jani Unité de Recherche sur les Hétéro Epitaxies et Applications URHEA Affiliations : Resume : InAs layer have been grown on GaAs substrate by atmospheric pressure metal-organic vapor phase epitaxy (MOVPE) at a temperature of 375°C. To study the bismuth effect, we have introduced three times a flow of trimethyl-bismuth (TMBi) into the reactor. The epitaxy was in situ monitored by spectral reflectance (SR) in the spectral range 200-1100 nm. 3D plot of the recorded reflectivity spectra R(t,λ) shows that the earlier wavelengths are the most sensitive to the flow effect of bismuth. Furthermore, the reflected intensity increases monotonously toward longer time (t), as a function of bismuth flow and the slope of this increase changes with the wavelength (λ). We attribute this behavior to refractive indices of bismuth and/or improvement of the InAs crystalline quality by reducing the dislocation density. | PC1 57 |
| 16:00 | Properties of misoriented GaAs substrates annealed under bismuth flow in atmospheric pressure metal–organic vapor phase epitaxy reactor Authors : I. Massoudi, M. M. Habchi, A. Rebey, B. El Jani Unité de Recherche sur les Hétéro Epitaxies et Applications URHEA Affiliations : Resume : In order to investigate in the bismide family, exactly oriented, 2° and 10° misoriented (1 0 0) GaAs toward [1 1 1] direction have been annealed at 375°C, into atmospheric pressure metalorganic vapor phase epitaxy (AP-MOVPE) horizontal reactor under trimethylbismuth flow (TMBi). The bismuth island formation was in situ monitored by spectral reflectance (SR) in the range of 400-1000 nm. We find that SR signal is sensitive to surface state change in particular for the short wavelengths. In addition, the Bi/GaAs surface morphology was investigated using the atomic force microscopy (AFM). We have studied quantitatively the misorientation effect on the surface roughness, the island densities and sizes. We prove the existence of particular behavior of Bi islands formed on the 2° misoriented GaAs. | PC1 58 |
| 16:00 | Properties of coupled and non coupled quantum structures made of different semiconductor materials Authors : Hung-Ju Lin1,2, Yu-jen Chen1,2, Judikael Le-Rouzo1, Sheng-Hui Chen2, François Flory1, Chang-Cheng Lee2 1 Aix-Marseille University, Institut Matériaux Microélectronique Nanosciences de Provence-IM2NP, CNRS-UMR 6242,Domaine Universitaire de Saint-Jérôme, Service 231,13397 Marseille Cedex 20, France 2 Thin Film Technology Center, National Central University, Taiwan Affiliations : Resume : Recently quantum structures have attracted a lot of attention as quantum confinement induces new optical and electronic properties. In particular, the energy bandgap of nanocrystal semiconductor materials depends on the nanocrystal size. Many applications are concerned such as lasers, light emitting diodes (QLEDs), solar cells.
A mathematical model, similar to the one used for multilayer waveguides, allows to describe the energy levels of electrons in structures composed of periodic and non-periodic multiple quantum wells. Our calculations are in good agreement with known results for single and infinite periodic quantum wells.
The bandgap dispersion with the nanocrystal size is presented for different materials such as ZnO, CdSe, PbS and Si.
The changes in the coupling between quantum wells with their distance are also analyzed and the density of probability of the electrons are given for different energy levels in different structures. It is shown that electrons can be more or less delocalized like electrons in molecules.
Measured optical properties of thin films including ZnO quantum dots (TFIQDs) and comparison with theoretical predictions are also presented. | PC1 59 |
| 16:00 | Synthesis of ZnO Nanoparticle Using Organic Compound Precursors Authors : Y.H. Song1, T. Y. Choi1, H. R. Lee2 and D.H. Yoon1, 2 * 1. School of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon 440-746, Republic of Korea 2. Sungkyunkwan Advanced Institute of Nanotechnology, Sungkyunkwan University, Suwon 440-746, Republic of Korea Affiliations : Resume : Recently, the nanocrystalline materials and nanotechnology has a considerable attention. Especially, as a wide band gap (Eg=3.37 Ev) semiconductor, ZnO has promising potential for a broad application such as transparent conductors, transparent UV-protection films, chemical sensors, and so on.
Until now, various synthesis methods have been used to produce ZnO including vapour deposition, thermal decomposition, hydrothermal method, and so on. However, above synthesis method for synthesizing ZnO nanoparticle is limited by the high synthesis costs.
Herein, we have synthesized ZnO nanoparticle using organic compound precursors that have the advantage of simple synthesis method. We investigated by analyzing their crystal structure and particle size with X-ray diffractometer (XRD) and transmission electron microscope (TEM), Field-emission scanning electron microscopy (FE-SEM). The thermogravimetry-differential thermal analysis was measured from 30 to 800 oC to confirm the reaction of organic compound and crystalline ZnO nanoparticle. Also, we analyzed the luminescence properties of the ZnO nanoparticle by using PL spectra | PC1 60 |
| 16:00 | Near-field optical measurement of the size-dependent dielectric function of single tungsten nanowire Authors : M. Kazan(1), Z. Sedaghat(2), A. Bruyant(2), J. Vaillant(2), S. Blaize(2), P. Morin(3), and P. Royer(2) 1-Department of Physics, American University of Beirut, Riad El-Solh 1107 2020, Beirut, Lebanon 2-Laboratoire de Nanotechnologie et d'Instrumentation Optique - Institut Charles Delaunay - Universit?e technologie de Troyes - CNRS FRE 2848, 12 rue Marie-Curie BP2060 10010 TROYES, Cedex France 3-ST Microelectronics, Crolles, France Affiliations : Resume : While intensive research works have been dedicated to the investigation of the size-dependent electronic confinement and its effect on the dielectric properties of nanostructured materials, there is still a lack of information on the size-dependent phonon confinement and the related dielectric properties. Such information would be crucial to gain insight into the effect of size on the harmonic and anharmonic terms of the interatomic forces and rationally tailor novel nanoscale materials for efficient technological applications. In this communication we tackle this issue and present an experimental analysis of the size-dependent complex dielectric function in the mid-infrared spectral range for free standing tungsten (W) nanowires of diameters exceeding the Bohr radius (rB). By this way we prevent the electronic confinement and we enhance the contribution of the confined phonon system to the overall optical response of the nanowire.
The scattering-type scanning near-field optical microscopy (s-SNOM) has proven its strong ability to recover the chemical fingerprint of materials at a nanometer scale due to its intrinsic sensitivity to the local dielectric function. Thus, in the infrared spectral range, this experiment appears to estimate eventual modifications of the sample or probe dielectric parameters related to phonon confinement. Therefore, we have performed mid-infrared near-field experiments using tungsten (W) nanowires of different diameters as nanoprobes. The samples scanned with the W probes were carefully designed flat surface gratings of copper lines spaced by 6 μm and embedded in intrinsic silicon in order to obtain a clear metal/dielectric contrast free of topographical artifacts.
When the bulk mid-infrared dielectric parameters of W are considered, all the existing electromagnetic models predict a noticeably higher signal on the metallic structure compared to the dielectric. Our experimental results are in perfect agreement with the theoretical prediction when relatively large diameter W probe is used. However, our experimental results showed that with decreasing the W probe diameter the contrast between the metallic and the dielectric region weakens until a reverse signal contrast occurs.
A phenomenological model as well as Green’s technique based model strongly suggests that the experimentally observed dependence of the probe diameter on the signal contrast must be due to a modification of the infrared complex dielectric function of the W probe that occurs because of the phonon confinement. For a small enough diameter, the dielectric function of W behaves as a nonmetal dielectric function and presents a strong anisotropy and material polarity signatures although W is a metallic nonpolar isotropic material. A physical model based on the elasticity theory is used to interpret such a dramatic modification in the nature of the W infrared complex dielectric function. | PC1 61 |
| 16:00 | The preparation of highly oriented TiO2 nanofiber by electrospinning Authors : Yu-Hsun Nien *, Yan-Sheng Tsai, Department of Chemical and Materials Engineering, National Yunlin University of Science and Technology, Taiwan Affiliations : Resume : The highly oriented TiO2 nanofiber was fabricated by electrospinning. The apparatus to manufacture highly oriented TiO2 nanofiber included roller, high voltage supplier, controllable syringe pump and syringe. Titanium(IV) isopropoxide and polyvinylpyrrolidone were used as precursor and auxiliary, respectively. Titanium(IV) isopropoxide and polyvinylpyrrolidone were well mixed with other essential reagent to form polymer solution. The polymer solution was poured into syringe and pumped at various flow rates. The electrospun nanofiber collected on the roller was roasted up to 600 °C and the highly oriented TiO2 nanofiber was formed as well as characterized using scanning electron microscope and X-ray Diffraction. | PC1 62 |
| 16:00 | Ion Track Technology to Nanotechnology: An Overview Authors : Hardev Singh Virk Director Research DAV Institute of Engineering and Technology, Kabir Nagar, Jalandhar-144008, Punjab (India) Affiliations : Resume : Ion Track Filters (ITFs) or Track-etched membranes (TEMs) became precursors to development of nanotechnology at GSI, Darmstadt (Germany) during 1990s. These filters were prepared by bombardment of thin polymer foils of Makrofol, Lexan, PVDF and PMMA or thin sheets of Muscovite mica using heavy ions. Author’s group used heavy ion beam facility available at GSI UNILAC, Darmstadt during 1990s to prepare ITFs in our laboratory. Heavy ion tracks in dielectric films offer unique possibilities for the realization of nanometer-sized structures at low cost and high throughputs. In combination with lithography they open up new ways for biofluidic, electric, magnetic and electro-optic device fabrication. Heavy ions produce along their path a nanometer channel of modified material with track diameter between 1 and 10 nm, adjustable by the chosen ion and its kinetic energy. The latent tracks created in irradiated materials may be used directly, e.g., creating conducting and magnetic nanowires in insulating matrices or they may be selectively etched into pores and then used for nanobiofluidic applications or as templates for growing micro/nanostructures. Commercial irradiation can produce ion track filters with pore density ranging from single pore to 108 pores per cm2 per second.
Several nanofabrication techniques have emerged during the last two decades for fabrication of nanodevices of wide variety. Ion track technology offers a broad variety of scientific challenges. The efficacy of the technique has been tested for growth of quantum dots, nano-crystals, nano-needles, flower patterns and nano wires with diameter in the range of 20-200nm. Porous alumina and polymer TEMs have been used as a template for fabrication of metallic and semi-conducting nanowires of uniform diameter. Nanowires have advantages over their bulk counterparts due to higher aspect ratio, diameter dependent band-gap, and increased surface scattering for electrons. Ion Track technology has been exploited in our laboratory to fabricate semiconductor nanowires and other heterostructures for investigation of electric, magnetic, optical and structural properties for their use in the area of electronics and opto-electronics in the nano-range. An overview of our investigations will be presented at EMRS meeting. | PC1 63 |
| 16:00 | Carbon nanotube reinforced micro-actuators Authors : Yu-Hsien Lin, Weileun Fang, Wen-Kuang Hsu Affiliations : Resume : Conductive composites made from carbon nanotubes (CNTs) loaded polymers show great potential for engineering and electronic applications and can be shaped into microelectro-mechanical devices. For example, CNT composites made micro-cantilever actuators exhibit a very low quality factor and beam displacement is onset at a value lower than 50 V. Actuations however are driven by thermal bimorph effect and beam deflection rate is low. In this work, suspended micro-beams made from parylene filled arrays of multi-walled carbon nanotubes deflect reversibly upon ac field application and actuation rate synchronizes with applied frequency. The thermal injection of polymer into CNT-arrays here produces a long-fiber matrix structure and tube packing efficiency reaches a maximum. At 5 V the strain reaches 0.15% and corresponding displacement is 21 m, twofold greater than that on MEMS device operating at a similar applied voltage. The deflection rate has been estimated to be 800 m/s at 10 Hz, faster than reported data on MEMS by one order of magnitude. The beam bending moment is estimated to be 0.0024-0.0032 kg.cm and field induced charge density at tube surfaces reaches 1.225×10-2 e per carbon atom, comparable with reported data on nanotube segregation and extraction from a bundle. | PC1 64 |
| 16:00 | Effect of carbon nanoparticle agglomeration on properties of conductive and sensitive polyisoprene nanocomposites Authors : Maris Knite1, Leonid Dolgov2, Kaspars Ozols1, Gita Sakale1, Juris Zavickis1, Raimonds Orlovs1 1Institute of Technical Physics, Riga Technical University, Latvia 2Institute of Physics, University of Tartu, Estonia Affiliations : Resume : Our recent research approved that electroconductive polyisoprene/nanostructured carbon composites (PNCC) perform promising piezoresistive and chemoresistive properties. It was also stated that such sensitive composites achieve the necessary electric conductivity only after vulcanization under specific conditions.
In this work we present an original attempt to investigate the development of percolative electroconductive carbon nanoparticle grid in PNCC during vulcanization phase. For this reason the “in situ” measurements of electric resistivity have been performed during the vulcanization process. Additionally, complex electric conductivity, dielectric spectroscopy, FTIR ATR, Raman spectroscopy and SEM measurements have been made for samples with discrete values of vulcanization time. SEM pictures showed subsequent growth of carbon nanoparticle agglomerates versus vulcanization time. Main processes have been evaluated that affect the formation of electro-conductive percolation grid during vulcanization phase.
An interesting correlation between SEM, FTIR ATR, Raman spectroscopy, dielectric spectroscopy and conductivity measurements of PNCC have been found.
Piezoresistivity, piezopermittivity as well as chemoresistivity effects have been tested for samples with different level of carbon nanoparticle agglomeration. | PC1 65 |
| 16:00 | NONPOWER INFLUENCE OF PULSE MAGNETIC FIELD ON PROCESSES OF ZIRCONIA SELF-ORGANIZATION Authors : Shilo A.V., Matuzenko O.A., Doroshkevich О.S., Konstantinova T.E., Danilenko I.A., Yaschischin I.О., Kryzhanovska K.V., Perekrestova L.D., Savchehko D.V. Affiliations : Resume : One of perspective methods allowing directionally influence on processes of nanopowders forming on the stage of zirconia dehydration there is the use of weak pulse magnetic-field (PMF). In particular, it is set that magneto-impulsive treatment in the process of thermal decomposition of zirconia influences on form and sizes of crystalline nanoparticles and changes character of process from linear to homogeneous. Noncontact, weak energy influence is the hi-tech reception of nanopowders disaggregating, which is utilized by us for the receipt of high-quality nanopowders on the basis of zirconia. However system study of effect not conducted. The optimum modes of treatment are unknown that limits possibilities of the use of PMF for the receipt of powders with the properties set in advance. This work is devoted to study of zirconia response on variation of frequency of PMF impulses following.
Model object is zirconia without maintenance of alloying admixtures was processed on the stage of drying (T=105°C) of weak (H=105 A/m) magnetic field impulses with frequencies of the following 0.5 Hz, 1 Hz, 5 Hz, 10 Hz and by the fixed duration of front edge (20 μs). Dependence of drying speed was probed on impulses following frequency.
It is discovered that use of PMF during hydrogel drying accelerates process of hydroxide dehydration. It is ascertain frequency selectivity of effect: on 1 Hz speed of dehydration is maximal frequency. Thus, PMF promotes efficiency of process of thermal decomposition of zirconia.
It confirmed that coagulative processes of self-organization in the nanopowders dispersible system proceed and after its transition from the aggregate state with liquid dispersion environment in the state with gas dispersion environment, and also on the subsequent stages of structural evolution of the system.
It is shown that decline of particles size at drying in the weak impulsive magnetic field [1] is investigation of acceleration of coagulative processes, realized in gas dispersion environment.
1. I.A. Danilenko, T.E. Konstantinova, G.K. Volkova, V.A. Glazunova, A.S. Doroshkevich // HPPT. – 2004. 14, № 3. – P. 49-57. | PC1 66 |
| 16:00 | Size-dependent optical properties of semiconductor-supported gold nanoparticles, nanopolyedrons and nanorods Authors : Maria M Giangregorio, Giuseppe V. Bianco, Pio Capezzuto, Giovanni Bruno and Maria Losurdo IMIP-CNR Department of Chemistry University of Bari via Orabona 4, 70026 Bari Italy Affiliations : Resume : The interest in the preparation, characterization and exploitation of the surface plasmon resonance (SPR) of metal nanoparticles, and specifically of gold (Au) nanoparticles (NPs), has grown exponentially.
In this contribution, we report on the size-dependence of the optical properties of gold nanoparticles, nanopolyedron and nanowires supported on a large variety of semiconductors and dielectrics including Si (100), SiC (0001) and sapphire (0001). A novel plasma sputtering methodology is used to tailor independently size and shape of Gold nanoparticles (NPs) directly deposited on the substrate to provide a semiconductor-based plasmonic platform. The Au NPs are characterized by interband transitions at energies above 2.5 eV, whose tails extend into the surface plasmon resonance (SPR) region, hence affecting the SPR energy, amplitude and broadening. Herein, we report the experimental evidence of the size dependence of the interband transitions and of the SPR for Au nanoobjects by exploiting plasmonic ellipsometry. Au nanoparticles are characterized structurally, morphologically and optically using spectroscopic ellipsometry (SE), atomic force microscopy (AFM) and transmission electron microscopy (TEM). The correlation between optical and properties and geometry is presented. Providing the size dependence of the dielectric function of Au NPs in the extended spectral range of 190-1700nm, and discussing the interconnection between the SPR and the interband transitions, this study as a whole represents a step ahead in the perspective of a better understanding of nanosize effect on optical properties and standardization of nanoparticles dielectric functions to rely on more accurate modeling of NPs behavior. | PC1 67 |
| 16:00 | Transport control of carbon nanoparticles in plasmas by biasing wall potential for plasma nano-factories Authors : KATSUSHI NISHIYAMA, HIROSHI MIYATA, DAISUKE YAMASHITA, KUNIHIRO KAMATAKI, GIICHIRO UCHIDA, NAHO ITAGAKI, KAZUNORI KOGA, and MASAHARU SHIRATANI, Kyushu University NAOKO ASHIKAWA, SUGURU MASUZAKI, KIYOHIKO NISHIMURA, AKIO SAGARA, and the LHD Experimental Group, National Institute for Fusion Science Affiliations : Resume : We are developing “plasma nano-factories” which are bottom-up processes and miniature versions of macroscopic conventional factories. A plasma nano-factory consists of production of nano-blocks and radicals (adhesives) in reactive plasmas, transport of nano-blocks towards a substrate, their arrangement on the substrate. There are three advantages of plasma nano-factories for fabricating nano-systems: they will realize 1) agglomeration control of nano-blocks, 2) transport control of nano-blocks, and 3) parallel processing over large area at low temperature. Here we report experimental results on transport control of carbon nanoparticles in plasmas by biasing wall potential. We produce carbon particles due to interaction between hydrogen helicon discharge plasmas and graphite. There are three kinds of particles produced: spherical nanoparticles below 1 um in size, flakes above 1 um, and agglomerates which consist of primary particles of 10 nm. The flux of spherical nanoparticles increases exponentially from 4E+4 per square meter sec to 4E+6 per square meter sec with increasing wall potential in a small area from -50 V to 50 V, whereas the fluxes of flakes and agglomerates are nearly constant values of per square meter sec regardless the wall potential. These results suggest that we can control transport of carbon nanoparticles in plasmas by biasing wall potential.
[1] S. Iwashita, et al., J. Plasma Fusion Res. Ser., 8, 0582 (2009). | PC1 68 |
| 16:00 | Rational fabrication of 2-D nanoporous graphene using an anodic aluminum oxide etching mask Authors : Jeong-Mi Lee1,3 , Jae-Hyun Lee1,2,3, Jong-Cheol Lee1,2,3, Sung Woo Hwang3,4, Dongmok Whang1,2,3* 1School of Advanced Materials Science and Engineering, 2 SKKU Advanced Institute of Nanotechnology Sungkyunkwan University, Suwon 440-746, Korea, 3Research Center for Time-domain Nano-functional Devices, Korea University, Seoul 136-701, Korea, 4School of Electrical Engineering, Korea University, Seoul 136-701, *dwhang@skku.edu Affiliations : Resume : Recently graphene has attracted much interest due to their novel physical properties and potential applications in nanoelectronics. However, lack of bandgap in large-area single-layer graphene is significant hurdle to overcome. In the past few years several methods have been attempted to open and tune a bandgap in graphene. For example, Bai et al. reported fabrication of a “graphene nanomesh”, which can open up a band gap of graphene. Here, we report a facile method to pattern a monolayer graphene into 2-dimensional (2D) nanoporous structures using thin anodic aluminum oxide (AAO) film as an etching mask. The electronic properties of the nanostructured graphene have been systematically controlled by adjusting the pore structure of AAO template. | PC1 69 |
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