bluuebunny/crossref_metadata_2025_split huggingface dataset:
One-axis Oriented CaBi4Ti4O15 and SrBi4Ti4O15 Films Prepared on Silicon Wafer by Chemical Solution Deposition Technique
Authors: Mizutani Yuki , Uchida Hiroshi , Funakubo Hiroshi , Koda Seiichiro 
Published: August 2010

AbstractOne-axis oriented bismuth layer-structured dielectric (BLSD) films were designed using perovskite buffer layers for assembling the crystal orientation and the dielectric properties of the BLSD crystals on silicon wafer. The BLSD crystals with the general formula of (Bi2O2)2+-(Am-1BmO3m+1)2- possess excellent dielectric permittivity with lower size effect and temperature coefficient of capacitance (TCC), as well as high electrical resistivity along to the c-axis direction. These phenomena would contribute for constructing high performance dielectric devices driven under harsh environment, e.g., at high-temperature condition above 100°C. In this study, thin films of CaBi4Ti4O15 and SrBi4Ti4O15, kinds of BLSD compounds with the number of BO6 octahedra in pseudo-perovskite blocks, m, = 4, were prepared by chemical solution deposition (CSD) technique on (100)LaNiO3/(111)Pt/TiO2/(100)Si and (100)SrRuO3// (100)LaNiO3/(111)Pt/TiO2/(100)Si substrates. These films consisted of crystalline phase of BLSD crystal with preferential crystal orientation of (001) plane normal to the substrate surface. Anisotropic crystal growth of BLSD occurred by the lattice matching between pseudo-perovskite blocks in BLSD crystal and (100)LaNiO3 or (100)SrRuO3 plane with perovskite structure. The dielectric constants (εr) of (001)-plane oriented CaBi4Ti4O15 and SrBi4Ti4O15 films were approximately 250-350 at room temperature. The r values of the CaBi4Ti4O15 and SrBi4Ti4O15 films increased slightly with ambient temperature. The TCCs at a temperature range from 25 to 200°C were approximately +103 - +514 ppm/K respectively, which were significantly different from those of (Ba,Sr)TiO3 thin films and would satisfy the performance requirement for driving at high-temperature condition.
Process-dependent Coercive Fields in Undoped and Mn-doped BiFeO3 Films Formed on SrRuO3/Pt(111) Electrodes by rf Sputtering
Authors: Kim Jeong Hwan , Funakubo Hiroshi , Sugiyama Yoshihiro , Ishiwara Hiroshi 
Published: August 2010

AbstractWe deposited BiFeO3 (BFO) thin films on SrRuO3 (SRO)/Pt bottom electrodes by radio-frequency (RF) sputtering. Some samples were formed at the substrate temperature of 550 °C, and others were foremed at 450 °C and post-annealed at 650°C for crystallization. The coercive field in the post-annealed BFO film was smaller than that in the 550°C-deposited BFO film. The coercive field in Mn-doped BiFeO3 (BFMO) films which were deposited at 550 ˚C on SRO/Pt(111) was lower than that in undoped BFO films. Degradation of the remanent polarization was less significant in the post-annealed BFO film.
Geometric Phase Analysis of Nano-Scale Strain Fields Around 90° Domains in PbTiO3/SrTiO3 Epitaxial Thin Film
Authors: Kiguchi Takanori , Aoyagi Kenta , Konno Toyohiko J. , Utsugi Satoru , Yamada Tomoaki , Funakubo Hiroshi 
Published: August 2010

AbstractThe nano-scale strain fields analysis around 90° domains and misfit dislocations in PbTiO3/SrTiO3 001 epitaxial thin film has been conducted using the geometric phase analysis (GPA) combined with high angle annular dark field - scanning transmission electron microscopy (HAADF-STEM). The films typically possess a-c mixed domain configuration with misfit dislocations. The PbTiO3 layer was formed from the two layer: the upper 200 nm layer shows the typical a- and c- mixed domain configuration where the a-domains are several tens nm in width; the bottom 100 nm layer shows the different domain configuration that the width is several nm. In the latter case, a-domains are terminated within the film and are short in length. On the other hand, the bottom of a-domains does not contact the film/substrate interface. It keeps away from the interface, and there is completely c-domain layer under a-domains. The HAADF-STEM-GPA shows that the strain fields around an a-domain and a misfit dislocation interact each other: the tensile strain field and lattice plane bending fit together. This result indicates that the a-domain originates from the misfit dislocation.
Magnetocaloric Properties of Rapidly Solidified Ni51.1Mn31.2In17.7 Heusler Alloy Ribbons
Authors: Sánchez Llamazares Jose , Hernando Blanca , Prida Víctor , García Carlos , Ross Caroline 
Published: August 2010

AbstractMagnetic entropy change and refrigerant capacity have been determined for a field change of 20 kOe around the second-order magnetic transition of austenite in as-quenched Ni51.1Mn31.2In17.7 alloy ribbons produced by melt spinning technique. Samples crystallize in a single-phase austenite with the highly ordered L21-type crystal structure and a Curie temperature of 275 K. The material shows a maximum magnetic entropy change of ΔSMmax= - 1.7 Jkg-1K-1, an useful working temperature range of 78 K (δTFWHM) and a refrigerant capacity of RC=132 Jkg-1 (RC= │ΔSMmax│ x δTFWHM). The considerable RC value obtained together with the fabrication via a single-step process make austenitic Ni-Mn-In ribbons of potential interest as magnetic refrigerants for room temperature magnetic refrigeration.
Structural Characterization of PLD-grown Nanometer Size Ferromagnetic NiFeMo Films
Authors: Banerjee Mitali , Majumdar Alak Kumar , Choudhary R J , Phase D M , Rai S , Tiwari Pragya , Lodha G S 
Published: August 2010

AbstractThin films of 3 different thicknesses each of Ni83.2Fe3.3Mo13.5 and Ni83.1Fe6.0Mo10.9alloys have been grown using Pulsed Laser Deposition (PLD) technique. Our motivation is to investigate the magnetic properties of a few nm thick Ni alloys with mostly Mo (4d element) addition since the corresponding soft ferromagnetic bulk alloys have shown very small coercivity of ˜ 0.1 Oe. Detailed structural characterization has been undertaken before probing the magnetic properties. Arc melted alloy buttons after homogenization are used directly as targets for the deposition. Films were deposited on single crystal Sapphire (0001) substrates using excimer laser. The structural characterization has been done by X-ray diffraction (XRD), X-ray reflectivity (XRR), Energy dispersive x-ray spectroscopy (EDS), and Atomic force microscopy (AFM). The X-ray diffraction pattern shows that the films are highly textured and grown along [111] direction of the alloys. They have high lattice strain which makes the films highly resistive and the resistance decreases with increasing thickness. The EDS measurements, using Scanning electron microscope (SEM), indicate that the compositions of the films are almost the same as those of the targets. Thickness, roughness, and density gradients are estimated using XRR measurements. The thinner films have higher roughness compared to the thicker ones for both the compositions. The films have density gradient across their thickness. The bottommost low density layer has high roughness which is supposed to be the result of initial non uniform coverage of the substrate. The density of the middle layer, having the lowest roughness, is approximately near the bulk value and it increases with increasing film thickness. The change in density is not due to the variation of composition; instead it is due to the variation of void densities in the layers. The topmost layer, having the lowest density and the highest roughness, is interpreted as a porous layer which is also evident from the AFM images.
Study of Magnetocaloric Properties of Ni-Mn-X (X = Ga, In) Heusler Alloys by Monte Carlo Technique
Authors: Buchelnikov Vasiliy , Sokolovskiy Vladimir , Taskaev Sergey , Entel Peter 
Published: August 2010

AbstractTwo theoretical Monte Carlo models have been presented for description of the positive and negative magnetocaloric effects of Heusler Ni-Mn-X (X = Ga, In) alloys undergoing first order coupled magnetostructural phase transition. For both models all quantities such as temperature dependence of the magnetic contribution to the total specific heat, magnetization and isothermal magnetic entropy change are in qualitative agreement with the available experimental data.
Electronic Impact of Inclusions in Diamond
Authors: Muller Erik M. , Smedley John , Raghothamachar Balaji , Gaowei Mengjia , Keister Jeffrey W. , Ben-Zvi Ilan , Dudley Michael , Wu Qiong 
Published: August 2010

AbstractX-ray topography data are compared with photodiode responsivity maps to identify potential candidates for electron trapping in high purity, single crystal diamond. X-ray topography data reveal the defects that exist in the diamond material, which are dominated by non-electrically active linear dislocations. However, many diamonds also contain defects configurations (groups of threading dislocations originating from a secondary phase region or inclusion) in the bulk of the wafer which map well to regions of photoconductive gain, indicating that these inclusions are a source of electron trapping which affect the performance of diamond X-ray detectors. It was determined that photoconductive gain is only possible with the combination of an injecting contact and charge trapping in the near surface region. Typical photoconductive gain regions are 0.2 mm across; away from these near-surface inclusions the device yields the expected diode responsivity.
Synthesis of Ca Decorated Carbon Nanostructures for Hydrogen Storage
Authors: Mirabile Gattia Daniele , Vittori Antisari Marco , Marazzi Renzo , Montone Amelia , Piscopiello Emanuela , Mingazzini Claudio 
Published: August 2010

AbstractThe AC powered electric arc has been used to synthesize single wall carbon nanohorns aggregates with Ca dispersed inside. To this purpose the electric arc has been ignited between two electrodes, one of which was constituted by a mixture of graphite and CaCO3. The experimental evidence on the microstructure and on the chemical composition has been obtained by observation with a transmission electron microscope equipped with X-ray microanalysis. X-ray diffraction revealed the presence of residual CaCO3 indicating that the process has still to be optimized. The experiment represents a first attempt to decorate carbon nanostructures with alkaline earth metals, in particular Ca, by this relatively simple method. These composites are theorized to adsorb relevant amounts of hydrogen. Further work will be focused to optimize the dispersion of Ca atoms in the carbon nanostructure.
Contactless Measurement of Carrier Lifetime on Silicon Ingots and Bricks
Authors: Swirhun James S , Forsyth M Keith , Mankad Tanaya , Sinton Ronald Alan 
Published: August 2010

AbstractHigh efficiency silicon solar cells demand the use of high lifetime silicon wafers. Characterization of boules and bricks before wafering allows poor quality material to be rejected before expensive processing steps. This paper extends simulation techniques previously used in quasi-steady-state-photoconductance to transient photoconductance decay measurements of high lifetime bulk samples. Simulated photogenerated carrier density profiles allow estimation of the bulk lifetime of a thick silicon sample with high surface recombination velocity.
Optimizing sulfurisation conditions in the fabrication of Cu2ZnSnS4absorber layers from electroplated precursors
Authors: Scragg Jonathan James , Wolverson Daniel , Zoppi Guillaume , Peter Laurence M 
Published: August 2010

AbstractUsing direct photoelectrochemical measurement of the photocurrent obtained from Cu2ZnSnS4(CZTS) absorber layers made by a two-stage electroplating-sulfurisation process, the influence of processing conditions (temperature, time, and pressure) on material quality was investigated with a view to understanding the long sulfurisation times usually found in the literature. The improvement in photocurrent due to KCN etching was also studied, and seems to be due both to removal of surface phases and also slower etching of the bulk material. The optimum sulfurisation time was found to be around 50 minutes, despite evidence that sulfur incorporation and phase formation are complete within 5 minutes. Slow grain growth was suggested as a rate-limiting factor, and a rate constant was derived based on a simple model.
Optimization of gettering processes of metallurgical-grade silicon for solar cell applications
Authors: Iskandarova Inna M. , Zvyagin Igor P. , Knizhnik Andrey , Konovalov Andrey V. , Potapkin Boris , Arutyunyan Natalya , Zaitsev Alexander I. , McNulty Thomas , Sommerer Timothy , Rahmane Mohamed , Lou Victor , Soloviev Stanislav , Vert Alexei , Selezneva Svetlana 
Published: August 2010

AbstractConversion efficiency of a solar energy in the electric is substantially determined not only by the total impurity concentration in solar cell element, but also by impurity chemical and physical state. Gettering processes, which are included in the technology of solar cell manufacturing, are usually used for such impurity redistribution. In order to optimize gettering processes we developed a program tool based on the fundamental physical and chemical laws. The description of physical and chemical behaviour of impurities in silicon is based both on known experimental data, and on calculations of necessary parameters by means of present-day thermodynamic and quantum-chemical methods. Developed tool helps to choose a gettering regime (a temperature profile, time, getter layer thickness) for optimization of these processes for the given initial chemical composition of the silicon wafer. Possibility of analysis of recombination activity of various types of defects in silicon on the basis of carrier lifetime criterion allows to obtain an estimation of efficiency of the gettering processes. Using this program tool we demonstrated that solar cell efficiency can be significantly increased by optimal choice of gettering conditions.
White Organic Light-Emitting Diodes with Fluorescent Tube Efficiency
Authors: Reineke Sebastian , Lindner Frank , Schwartz Gregor , Seidler Nico , Walzer Karsten , Lüssem Björn , Leo Karl 
Published: August 2010

AbstractWhite organic LEDs are seen as one of the next generation light-sources, with their potential to reach internal efficiencies of unity and their unique appearance as large-area and ultrathin devices. However, to replace existing lighting technologies, they have to be at least on par with the state-of-the-art. In terms of efficiency, the fluorescent tube with 60-70 lumen per Watt (lm W-1) in a fixture is the current benchmark. In the scientific literature, so far only values of 44 lm W-1 have been published for white OLEDs.Here, we present results (Reineke et al., Nature 459, 234 (2009)) of white OLEDs with 90 lm W-1 at an illumination relevant brightness of 1,000 candela per square meter (cd m-2). Extracting all light from the glass substrate using a 3D light extraction system, we even obtain 124 lm W-1. In order to achieve such high efficacy values, we reduced the energetic losses prior to photon emission that include ohmic and thermal relaxation losses, leading to very low operating voltages. This is accomplished by the use of doped transport layers and a novel, very energy efficient emission layer concept. Equally important, we addressed the optics of the OLED architecture, because about 80% of the generated light remains trapped in conventional devices. Therefore, we used high refractive index substrates to couple out more light and placed the emission to the second field antinode to avoid plasmonic losses. Our devices are also characterized by an outstandingly high efficiency at high brightness, reaching 74 lm W-1 at 5,000 cd m-2.
Hybrid P3HT/CdSe Photovoltaic Cells: Effects of Nanocrystal Size and Device Aging
Authors: Yang Jihua , Zhou Renjia , Tang Aiwei , Xue Jiangeng 
Published: August 2010

AbstractHybrid solar cells based on conjugated polymers and colloidally synthesized inorganic nanoparticles have been recognized as an alternative to all-organic solar cells due to the intrinsically higher charge transport property in inorganic component. In this work, CdSe nanoparticles with different sizes, served as the electron acceptor, have been used together with poly(3-hexylthiophene) (P3HT) as the active layer for the hybrid solar cells. The power-conversion efficiency (ηp) of these devices strongly depends on the size of the CdSe nanoparticles, increasing from ηp ˜0.5% for 4.0 nm size nanoparticles to ηp ˜2.4% for 6.8 nm size nanoparticles under AM 1.5 G solar illumination. Furthermore, the devices also exhibit an unusual initial aging period when exposed to the air, which results in a significant enhancement in the short-circuit current, open-circuit voltage and power conversion efficiency.
HRTEM Study of Oxide Nanoparticles in 16Cr-4Al-2W-0.3Ti-0.3Y2O3 ODS Steel
Authors: Hsiung Luke , Fluss Mike , Wall Mark , Kimura Akihiko 
Published: August 2010

AbstractCrystal and interfacial structures of oxide nanoparticles in 16Cr-4Al-2W-0.3Ti-0.3Y2O3 ODS ferritic steel have been examined using high-resolution transmission electron microscopy (HRTEM) techniques. Oxide nanoparticles with a complex-oxide core and an amorphous shell were frequently observed. The crystal structure of complex-oxide core is identified to be mainly monoclinic Y4Al2O9 (YAM) oxide compound. Orientation relationships between the oxide and matrix are found to be dependent on the particle size. Large particles (> 20 nm) tend to be incoherent and have a spherical shape, whereas small particles (< 10 nm) tend to be coherent or semi-coherent and have a faceted interface. The observations of partially amorphous nanoparticles lead us to propose three-stage mechanisms in order to rationalize the formation of oxide nanoparticles containing core/shell structures in as-fabricated ODS steels.
Radiation Response of a 12YWT Nanostructured Ferritic Steel
Authors: Miller Michael , Hoelzer David , Russell Kaye F. 
Published: August 2010

AbstractIn order to evaluate the radiation response of 12YWT nanostructured ferritic steel to high dose neutron irradiation, the solute distribution, and size, number density, and compositions of nanoclusters in the unirradiated condition and after neutron irradiation to a dose of 3 dpa at a controlled temperature of 600 °C were estimated by atom probe tomography. No statistical difference in the average size or size distribution of the nanoclusters was found between the unirradiated and irradiated conditions. Therefore, these nanostructured ferritic steels are promising candidate materials for use under extreme conditions in future generations of advanced reactors.
Densification of Inert Matrix Fuels Using Naturally-occurring Material as a Sintering Additive
Authors: Miwa Shuhei , Osaka Masahiko , Usuki Toshiyuki , Yano Toyohiko 
Published: August 2010

AbstractWe proposed a new concept for densification of inert matrix fuels containing minor actinides. In this concept, magnesium silicates which are both a naturally-occurring material and asbestos waste were used as a sintering additive which protects public health by safely disposing of the asbestos waste. In this study, the effects of magnesium silicate additives on the densification behaviors of MgO, Mo and CeO2 were experimentally investigated. The densities of MgO and CeO2 pellets increased with only 1 wt.% additives of MgSiO3 and Mg2SiO4. The densities of Mo pellets showed little change with additives.
Effect of Americium and Simulated Fission Products Addition on Oxygen Potential of Uranium-Plutonium Mixed Oxide Fuels
Authors: Tanaka Kosuke , Osaka Masahiko , Kurosaki Ken , Muta Hiroaki , Uno Masayoshi , Yamanaka Shinsuke 
Published: August 2010

AbstractThe oxygen potentials at 1273 K of mixed oxide (MOX) fuels with Am and 26 kinds of fission product elements (FPs), simulating low-decontaminated MOX fuel and high burn-up of up to 250 GWd/t, have been measured by using thermogravimetric analysis (TGA). The oxygen potentials for simulated low-decontaminated MOX fuels were higher than the fuels without FPs and increased with increasing simulated burn-up.
Are Slit Pores in Carbonaceus Materials Real?
Authors: Romero Cristina , Valladares Ariel A. , Valladares R. M. , Valladares Alexander 
Published: August 2010

AbstractNanoporous carbon is a widely studied material due to its potential applications in hydrogen storage or for filtering undesirable products. Most of the developments have been experimental although some simulation work has been carried out based on the use of graphene sheets and/or carbon chains and classical molecular dynamics. The slit pore model is one of the oldest models proposed to describe porous carbon. Developed by Emmet in 1948 [1] it has been recurrently used and in its most basic form consists of two parallel graphene layers separated by a distance that is taken as the width of the pore. Its simplicity limits its applicability since experimental evidence suggests that the walls of the carbon pores have widths of a few graphene layers [2], but it still is appealing for computational simulations due to its low computational cost. Using a previously developed ab initio approach to generate porous semiconductors [3] we have obtained porous carbonaceous materials with walls made up of a few graphene layers (four layers), in agreement with experimental results; these walls are separated by distances comparable to those used in the slit pore model [4]. This validates the idea of a modified slit pore model obtained without the use of ad hoc suppositions. Structures will be presented, analyzed and compared to available experimental results.
Twining and Slip Activity in Magnesium <11-20> Single Crystal
Authors: Kim Gyu Seok , Yi Sangbong , Huang Yuanding , Lilleodden Erica 
Published: August 2010

AbstractUniaxial μ-compression tests have been performed on single crystal Mg with a <11-20> compression direction, an orientation unfavorable for basal slip. Results show that the early stages of deformation proceed via both twinning and dislocation plasticity. Twinning leads to a reorientation of the crystal favorable for basal slip, typically with the <2-1-1-3> aligned with the compression direction. At a critical strain a large strain burst occurs, and is associated with both rapid propagation of the twin and the activation of basal slip within the twin. Such a mechanistic picture of the deformation behavior is revealed through SEM, EBSD and TEM characterization of the deformation structures.
Variable Elastic-Plastic Properties of the Grain Boundaries and Their Effect on the Macroscopic Flow Stress of Nano-Crystalline Metals
Authors: Lewandowska Malgorzata , Dobosz Romuald , Kurzydlowski Krzysztof J 
Published: August 2010

AbstractThe paper reports new experimental results describing properties and microstructure of nanocrystalline metals. Nano- and sub-micron aluminium has been produced by hydrostatic extrusion at ambient tempearture. The structures have been quantified in terms of size of grains and misorientation of the grain boundaries. Different average size of grains, variable normalized width of grain size distribution and changing grain boundary misorientation distribution functions have been revealed depending on processing parameters. The results of the tensile tests showed that the average grain size, grain size distribution and the distribution function of misorientation angles influence the flow stress of obtained nano-metals. In order to explain the observed difference in the properties of nano- and micro-sized aluminium alloys, a Finite Element Method models have been developed, which assumes that both grain boundaries and grain interiors may accommodated elastic and non-linear plastic deformation. These models assumed true geometry of grains (which differed in size and shape). Also, variable mechanical properties of grain boundaries have been taken into account (elastic modulus, yield strength and work hardening rate). The results of modelling explain in a semi-quantitative way macroscopic deformation of nano-crystalline aggregates. In particular, they illustrate the importance of the interplay between properties of grain boundaries and grain interiors in elastic and plastic regime.