bluuebunny/crossref_metadata_2025_split huggingface dataset:
Simulating Thermal Cycling and Isothermal Deformation Response of Polycrystalline NiTi
Authors: Manchiraju Sivom , Gaydosh Darrell J. , Noebe Ronald D. , Anderson Peter M. 
Published: April 2011

ABSTRACTA microstructure-based FEM model that couples crystal plasticity, crystallographic descriptions of the B2-B19′ martensitic phase transformation, and anisotropic elasticity is used to simulate thermal cycling and isothermal deformation in polycrystalline NiTi (49.9at% Ni). The model inputs include anisotropic elastic properties, polycrystalline texture, DSC data, and a subset of isothermal deformation and load-biased thermal cycling data. A key experimental trend is captured—namely, the transformation strain during thermal cycling is predicted to reach a peak with increasing bias stress, due to the onset of plasticity at larger bias stress. Plasticity induces internal stress that affects both thermal cycling and isothermal deformation responses. Affected thermal cycling features include hysteretic width, two-way shape memory effect, and evolution of texture with increasing bias stress. Affected isothermal deformation features include increased hardening during loading and retained martensite after unloading. These trends are not captured by microstructural models that lack plasticity, nor are they all captured in a robust manner by phenomenological approaches. Despite this advance in microstructural modeling, quantitative differences exist, such as underprediction of open loop strain during thermal cycling.
Transition from Microscale-Faceted Structures to Ultra-Dense GaN Nanowires
Authors: Teker Kasif , Oxenham Joseph A. 
Published: April 2011

ABSTRACTCreation of nanoscale building blocks with various sizes and shapes are critical for the progress of nanotechnology. The synthesis of GaN nanowires by chemical vapor deposition (CVD) using Ga and NH3 as source materials on SiO2/Si substrate was systematically studied. Various types of catalyst materials, including gold (film and nanoparticle), nickel (film and nanoparticle), silver, cobalt and iron, have been used. The growth runs have been carried out at temperatures between 800 and 1100oC under two different carrier gases; H2 and Ar. Initial growth runs using Ar as carrier gas resulted in microscale-faceted nanostructures and short nanorods regardless of the growth temperature or reactor pressure. We have successfully achieved ultra-dense interwoven long nanowires using hydrogen as carrier gas at 1100oC. In fact, the yield has been very high for both gold and nickel catalysts. It should be emphasized that combination of high-temperature and hydrogen has resulted in ultra-dense interwoven long GaN nanowires. These results suggest a radical change in growth kinetics at high temperatures in the presence of H2. The GaN nanowire diameters are in the range of 15 nm to 50 nm and lengths up to hundred microns. The grown nanowires have been characterized by scanning electron microscopy (SEM with EDS), atomic force microscopy (AFM), x-ray diffraction (XRD), and transmission electron microscopy (TEM).
Application of liquid desiccant for enhanced lifetime of active
matrix organic light emitting diodes
Authors: Lee Byoung Duk , Cho Yoon-Hyung , Oh Minho , Kim Yong Tak , Cho Sang-Hwan , Lee So Young , Chung Yoon Ah , Song Seung Yong , Lee Jong Hyuk , Kim Sung Chul 
Published: April 2011

ABSTRACTTo enhance the lifetime of large-sized active matrix organic light emitting
diodes (AMOLEDs), we developed a liquid desiccant for encapsulation. The
liquid desiccant was prepared by mixing nano-sized calcium oxide (CaO)
powders and silicone binder including polyalkylalkenylsiloxane,
polyalkylhydrogensiloxane and platinum compound. It was confirmed that
liquid desiccant had an effect on absorption of penetrated moisture and
oxygen through calcium tests. Also, the test cells encapsulated with only
epoxy sealant dispensed at the edge of the cell developed dark spots within
100 hrs, which grew larger with time at 85 oC and 85 % R.H. On the other hand, the test cell sealed with epoxy
sealant and liquid desiccant showed no dark spots and retained 97% of its
initial luminance even after being stored for 800 hrs at 85 oC and 85 % R.H. Furthermore, the accelerating storage lifetimes of
31-inch bottom-emitting AMOLEDs with epoxy sealant and liquid desiccant
showed about 1000 hrs. These results suggest that the liquid desiccant can
be applied to encapsulation of large-sized AMOLEDs.
Ultrafast Charge Separation at a Single-walled Carbon Nanotube –
Polymer Interface
Authors: Stranks Samuel D. , Weisspfennig Christian , Parkinson Patrick , Johnston Michael B. , Herz Laura M. , Nicholas Robin J. 
Published: April 2011

ABSTRACTWe report the observation of an ultrafast (~ 430 fs) charge transfer process
at the interface between a single-walled carbon nanotube (SWNT) wrapped by a
semi-conducting polymer, poly(3-hexylthiophene) (P3HT), creating free
polarons on both materials. The addition of excess P3HT as a surrounding
network allows these free polarons to be long-lived at room temperature. Our
results suggest that SWNT-P3HT blends incorporating only 1% fractions of
SWNTs can achieve a charge separation efficiency comparable to a
conventional 60:40 P3HT-fullerene blend, provided small-diameter tubes are
embedded in an excess P3HT matrix.
Correlation among the ionization potential, built-in potential,
and the open-circuit voltage of multi-layered organic photovoltaic
devices
Authors: Itoh Eiji , Shirotori Toshiki 
Published: April 2011

ABSTRACTWe have investigated the current-voltage characteristics of the
multi-layered photovoltaic devices consisting of ITO/oxide /p-type
(donor)/fullerene/ bathocuproine (BCP)/ Al structures. We chose various
p-type (donors) small molecules and polymers in order to tune the values of
ionization potential (IP) of donor molecules. The open-circuit voltage (Voc)
increases with the increment of IP of donor materials. However,
VOC was limited at ~0.6-0.7V for the devices without oxide
layer. On the other hand, the VOC increases up to 0.9V for the
devices with NiO and to ~ 1.1V for the devices with MoOX as a
hole extraction buffer layer, respectively. We also estimated the
work-function differences between Al and the oxide as 0.7, 0.9-1.0, and
1.2-1.3 eV for the device without oxide, with NiO, and with MoOX,
respectively. We therefore concluded the value of VOC is limited
by the lower part of VOC and energy difference between the LUMO
of fullerene and the HOMO of donor ΔE.
Probing the Orbital Levels of Engineered Fullerenic Molecules
from a Nonvolatile Memory Cell
Authors: Xu Sarah Q. , Shaw Jonathan , Kan Edwin C. 
Published: April 2011

ABSTRACTThe Coulomb blockade behavior was observed for both C60-PCBM and
C70-PCBM at room temperature utilizing a nonvolatile memory
cell fabricated through a liquid-transfer process. Room-temperature and
low-temperature (10K) electrical characterizations verified the blockade
effect was originated from both molecular energy levels and single electron
charging energy. Molecular orbital energy was extracted and shown good
agreement with the literature [1].The successful integration and operation
of this hybrid structure signified a strong potential for molecule-based
electronic device design.
Effects of air and light exposure on the opto-electronic
properties of polymer:fullerene solar cells
Authors: Sio Antonietta De , Como Enrico Da , Hauff Elizabeth von , Parisi Jürgen 
Published: April 2011

ABSTRACTIn this study we investigate how exposure to ambient air and light during
device processing affects the opto-electronic properties of
poly-3-hexylthiophene (P3HT) :
[6,6]-phenyl-C61-butyric acid methyl ester (PCBM) bulk
heterojunction solar cells (BHJ). The properties of pure P3HT layers
prepared in an inert atmosphere, under ambient conditions, and additionally
degraded under light in ambient conditions were investigated using
photoluminescence (PL) and photoinduced absorption (PIA). It was observed
that exposure to air during processing leads to oxygen doping of the
polymer. Exposure to air combined with light was found to significantly
decrease the PL and PIA signals. The current-voltage (I-V) and external
quantum efficiency (EQE) characteristics of solar cells fabricated in an
inert atmosphere were compared to solar cells processed under ambient
conditions. It was observed that processing in air leads to a reduction in
the photocurrent in the devices which is attributed to electron trapping by
oxygen in the active layer.
The Study of Improving the Conversion Efficiency and Reducing the Thickness of the HIT Solar Cell
Authors: Hirayama Yasuko , Inoue Hirotada , Matsuyama Kenta , Tsunomura Yasu umi , Fujishima Daisuke , Yano Ayumu , Taira Shigeharu , Nishiwaki Takeshi , Asaumi Toshio , Kinoshita Toshihiro , Taguchi Mikio , Sakata Hitoshi , Maruyama Eiji 
Published: April 2011

ABSTRACTIn order to reduce the power-generating cost of silicon solar cells, it is necessary to achieve a high conversion efficiency using a thinner crystalline silicon (c-Si) substrate. The HIT solar cell is an amorphous silicon (a-Si) /crystalline silicon (c-Si) heterojunction solar cell that makes it possible to realize excellent surface passivation and hence high open circuit voltage (Voc). In addition, its symmetrical structure and a low-temperature fabrication process that is under 200°C provide advantages in reducing thermal and mechanical stresses within the device so that it can easily be applied to thinner solar cells. We fabricated HIT solar cells using thin wafers from 58-98 μm, and achieved a 22.8% conversion efficiency with a HIT solar cell using a 98-μm-thick wafer, and an excellent Voc value of 0.747 V with a HIT solar cell using a 58-μm-thick wafer.
Dispersed Nanoelectrodes for High Performance Gas Sensors
Authors: Tricoli Antonio , Pratsinis S.E. 
Published: April 2011

ABSTRACTIntegration of nanoparticles in electronic devices such as sensors, actuators, batteries, solar and fuel cells is a key technological development for advancing their performance and miniaturization. Frequently, however, the benefit of nanoscale is lost by poor electrical conductivity through such nanoparticle structures. As a result, it is challenging to achieve both attractive conductivity and maximal performance by the device. Recently it was demonstrated that flame-made nanoparticles can be directly deposited onto substrates to form porous thick films of controlled thickness for application as gas sensors. The mechanical stability of FSP-deposited layers can be greatly increased by in situ annealing showing compatibility even with fragile CMOS-based substrates. Here, a novel asymmetric electrode assembly is described that greatly reduces the resistance of a nanostructured layer and maximizes its performance: Nanoparticles with tailored conductivity (e.g. Ag, CuO, Au) serving as electrodes are stochastically deposited by a scalable technique either below or above a functional (e.g. SnO2, TiO2, WO3) film decreasing the effective length of the resistive components. As the distance between electrodes is at the nanoscale, the total film resistance is drastically decreased. The feasibility of this assembly is demonstrated with solid state sensors having controlled resistance and exceptionally high sensitivity.
Growth of CaFeOX/LaFeO3 Superlattice on SrTiO3(100) Substrates
Authors: Iwata Nobuyuki , Huijben Mark , Rijnders Guus , Yamamoto Hiroshi , Blank Dave H. A. 
Published: April 2011

ABSTRACTThe CaFeOX(CFO) and LaFeO3(LFO) thin films as well as superlattices were fabricated on SrTiO3(100) substrates by pulsed laser deposition (PLD) method. The tetragonal LFO film grew with layer-by-layer growth mode until approximately 40 layers. In the case of CFO, initial three layers showed layer-by-layer growth, and afterward the growth mode was transferred to two layers-by-two layers (TLTL) growth mode. The RHEED oscillation was observed until the end of the growth, approximately 50nm. Orthorhombic twin CaFeO2.5 (CFO2.5) structure was obtained. However, it is expected that the initial three CFO layers are CaFeO3 (CFO3) with the valence of Fe4+. The CFO and LFO superlattice showed a step-terraces surface, and the superlattice satellite peaks in a 2θ-θ and reciprocal space mapping (RSM) x-ray diffraction (XRD) measurements, indicating that the clear interfaces were fabricated.
Processing iron aluminides by heavy deformation for improved room temperature strength-ductility and for high temperature creep strength
Authors: Morris David G. , Muñoz-Morris Maria Antonia 
Published: April 2011

ABSTRACTIron aluminides show many interesting properties, but still show relatively poor ductility at room temperature and only moderate creep resistance at temperatures above about 600ºC. Processes of severe plastic deformation have been investigated for a wide range of ductile alloys over the past decade, but have hardly been considered for intermetallics. This presentation discusses two studies aimed at refining microstructure by the use of severe plastic deformation of iron aluminides. The first considers processing Fe3Al by heavy cold rolling, followed by annealing for recovery or recrystallization, with an objective of refining grain size to improve strength at the same time as ductility. The high strength and poor ductility of the work hardened material leads to a danger of cracking during rolling, which is a problem for manufacturing large quantities of healthy material. Suitable rolling and recovery treatments can, nevertheless, lead to strong materials with some plastic ductility. A different technique of multidirectional, high-strain and high-temperature forging applied to a boride-containing Fe3Al alloy produces a material with large grain size and refined dispersion of boride particles. These particles lead to a considerable increase in creep strength under conditions of moderate stresses at temperatures around 700ºC. This high-strain forging technique can be seen as an intermediate processing method between conventional wrought metallurgy and mechanical-alloying powder metallurgy. This technique offers the possibility to improve high temperature behaviour of such intermetallics containing second-phase dispersions, and can be scaled to produce large quantities of high-quality material.
Radiation-Enhanced Aqueous Dissolution of Minerals
Authors: Dukes Catherine A. , Baragiola Raúl A. 
Published: April 2011

ABSTRACTMineral samples of varying petrology, exposed to ion irradiation and subsequently immersed in water or exposed to a humid environment, show up to 60% depletion of specific surface atoms (Mg, Ca, K, and Na) — a depletion that is enhanced 26,000x compared to unirradiated surfaces. Surface depletions of irradiated minerals exposed to water were measured using X-ray photoelectron spectroscopy. Irradiations were performed with 4 keV Ar+ ions at fluences from 1014 – 1019 ion cm-2; samples were subsequently exposed to liquid water or humid air (35º C and 70% RH). Analyses were done before irradiation, after irradiation, and after exposure to water, allowing identification of changes in composition due solely to ion irradiation or combined with water exposure. Before water exposure, we observe no significant change in stoichiometry of the minerals for ion fluences <1018 ions cm-2. We find incongruent depletion of 60% Mg for forsterite after exposure to humidity or three minutes (or more) water immersion. Augite undergoes reduction in the surface concentration of approximately 30% Mg, 40% Ca, and 55% Na after 1.9 x 1017 Ar cm-2 and immersion in HPLC water (pH: 6.8) for three minutes. Depth profiles of the irradiated, water exposed, minerals show that the depth of the depleted region is on the order of the ion range, ~15nm. In addition, preliminary results for albite, anorthoclase, and microcline in water show significant depletions of Na, Na and K, and K, respectively, from the mineral surface.
Fatigue resistance of Fe3Al-based alloys
Authors: Gang Florian , Krüger Manja , Laskowsky Alexandra , Rühe Heike , Schneibel Joachim H. , Heilmaier Martin 
Published: April 2011

ABSTRACTThe low cycle fatigue (LCF) behaviour of two cast as well as two hot extruded Fe3Al-based iron aluminide alloys, either with or without Cr, is investigated. All four alloys contain microalloying additions of Zr, Nb, C and B. Fatigue tests were carried out under strain control for strain amplitudes in the range of εa = 0.1 – 0.4 % for the cast alloys and εa = 0.1 – 0.7 % for the extruded materials, at frequencies of 1 Hz (extruded Fe3Al) and 3 Hz (all other alloys) and at room temperature and 300 °C. Within the first cycles all alloys show strong cyclic hardening. Furthermore the fatigue strain – fatigue life curves are steeper at 300 °C than at room temperature, showing increased fatigue strength at low cycle numbers due to increasing ductility and decreased fatigue strength at increasing cycle numbers because of reduced yield strength. Cr is found to have only a negligible influence on the fatigue behaviour of Fe3Al-based alloys. Comparison between the differently processed materials shows superior LCF properties of the hot extruded iron aluminides due to significantly smaller grain sizes.
Physical Metallurgy and Properties of β-solidifying TiAl Based Alloys
Authors: Clemens Helmut , Schmoelzer Thomas , Schloffer Martin , Schwaighofer Emanuel , Mayer Svea , Dehm Gerhard 
Published: April 2011

ABSTRACTIn this paper, the physical metallurgy and properties of a novel family of high-strength γ-TiAl-based alloys is reviewed succinctly. These so-called TNM™ alloys contain Nb and Mo additions in the range of 3 - 7 atomic percent as well as small additions of B and C. For the definition of the alloy composition thermodynamic calculations using the CALPHAD method were conducted. The predicted phase transformation and ordering temperatures were verified by differential scanning calorimetry and in situ high-energy X-ray diffraction. TNM alloys solidify via the β-phase and exhibit an adjustable β-phase volume fraction at temperatures, where hot-working processes are performed. Due to the high volume fraction of β-phase these alloys can be processed isothermally as well as under near conventional conditions. In order to study the occurring deformation and recrystallization processes during hot-working, in situ diffraction experiments were conducted during compression tests at elevated temperatures. With subsequent heat-treatments a significant reduction of the β-phase is achieved. These outstanding features of TNM alloys distinguish them from other TiAl alloys which must exclusively be processed under isothermal conditions and/or which always exhibit a high fraction of β-phase at service temperature. After hot-working and multi-step heat-treatments, these alloys show yield strength levels > 800 MPa at room temperature and also good creep resistance at elevated temperatures.
Characterization of oxide particles in ODS austenitic stainless steel after heavy ion irradiation up to high doses
Authors: Oka Hiroshi , Yamazaki Yosuke , Kinoshita Hiroshi , Hashimoto Naoyuki , Ohnuki Somei , Yamashita Shinichiro , Ohtsuka Satoshi 
Published: April 2011

ABSTRACTOxide dispersion strengthened austenitic stainless steel (ODS316), which is based on advanced SUS316 steel, has been developed by mechanically alloying and hot extrusion. Hafnium and titanium were added to make a fine distribution of oxide particles. The stability of oxide particles dispersed in ODS316 under irradiation was evaluated after 250 keV Fe+ irradiation up to high doses at 500 °C. TEM observation and EDS analysis indicated that fine complex oxide particles with Y, Hf and Ti were mainly dispersed in the matrix. There are no significant changes in the distribution and the size of oxide particles after irradiation. It was also revealed that the constitution ratio of Ti in complex oxide appeared to be decreased after irradiation. This diffuse-out of Ti during irradiation could be explained by the difference in oxide formation energy among alloying elements.
Glassy Alloy Composite and Non-equilibrium Crystalline Alloy for Information Technology Applications
Authors: Nishiyama N. , Takenaka Kana , Miura Haruko , Saidoh Noriko , Inoue Akihisa 
Published: April 2011

ABSTRACTPresent progress in developments of glassy alloy composites for bit-patterned-media and non-equilibrium Cu-based alloys for conductive materials of electrical connectors are reviewed. It is proven that the imprinting of the Pd-based glassy alloy thin film is favorable for the formation of nano-structured devices. Detailed imprinted morphologies formed by different imprinting conditions were examined. In addition, technology of large area imprinting up to 2.5 inches area has been successfully developed and it is now available for production. These technological developments will be utilized for next generation bit-patterned-media with high data density. A newly developed non-equilibrium Cu-Zr-Ag alloy was prepared into sheet form by the combination of casting, cold rolling and annealing. The alloy sheet exhibited high tensile strength of exceeding 1500 MPa and good electrical conductivity of 30% IACS. However, bending ductility should be improved for the actual production of connector. Through the several examinations, remaining issues that should be solved are discussed in the framework of industrialization and commercialization. These obtained results suggest that the glassy alloy composite or non-equilibrium alloy designed by the glass-forming rules have a great potential to develop innovative products in the near future.
Epitaxial growth of V2O3 on Al2O3 by reactive MBE
Authors: Dillemans Leander , Tran Tuan , Kabir Bhuiyan Md. Nurul , Smets Tomas , Menghini Mariela , Lieten Ruben , Seo Jin Won , Locquet Jean-Pierre 
Published: April 2011

ABSTRACTVanadium oxides are strongly correlated electron systems that are interesting both from a fundamental scientific point of view and for possible future applications including memory and sensors. In this contribution, we report on the epitaxial growth of V2O3 thin films on c-Al2O3 (0001) with molecular beam epitaxy and atomic oxygen. We studied the influence of deposition rate and substrate temperature on the structural properties and the metal-insulator transition.
Effect of Vacancy-Site Occupation in Half-Heusler Compound ZrNiSn on Phase Stability and Thermoelectric Properties
Authors: Kimura Yoshisato , Tanoguchi Toshiyasu , Sakai Yasuhiro , Chai Yaw-Wang , Mishima Yoshinao 
Published: April 2011

ABSTRACTThe half-Heusler compound ZrNiSn has a quite small solubility for Ni from the stoichiometric composition towards the Ni-rich direction since Ni atoms are not supposed to occupy the vacancy-site. Nevertheless, Co and Ir atoms preferably occupy the vacancy-site of ZrNiSn, which is contrary to the prediction that they would substitute for Ni sites. This implies that the phase stability of the compound gradually changes toward that of the Heusler compound Zr(Ni,M)2Sn (M = Co, Ir). It has been confirmed that there exists a two-phase field between half-Heusler Zr(Ni,Cox)Sn and Heusler Zr(Ni,Co)2Sn. The n-type thermoelectric property of ZrNiSn can be converted to p-type by the addition of Co and Ir within the compositional range of the half-Heusler phase. The occupation of vacancy sites by Co and Ir atoms leads to a drastic reduction in the thermal conductivity owing to the enhancement of phonon scattering. With further Co addition, the Heusler phase Zr(Ni,Co)2Sn alloys show metallic behavior.