bluuebunny/crossref_metadata_2025_split huggingface dataset:
Long-Living Emitting Electrochemical Cells Based on Supramolecular π-π Interactions
Authors: Costa Rubén D. , Ortí Enrique , Graber Stefan , Neuburger Markus , Hausecroft Catherine E. , Constable Edwin C. 
Published: August 2010

AbstractThe complex [Ir(ppy)2(dpbpy)][PF6] (Hppy = 2-phenylpyridine, dpbpy = 6,6'-diphenyl-2,2'-bipyridine) has been prepared and evaluated as an electroluminescent component for light-emitting electrochemical cells (LECs). The complex exhibits two intramolecular face-to-face π-stacking interactions and long-lived LECs have been constructed; the device characteristics are not significantly improved in comparison to analogous LECs with 6-phenyl-2,2'-bipyridine with only one π-stacking interaction.
Misfit Strain Relaxation by Secondary Phase Formation in Multiferroic BiFeO3 Epitaxial Thin Films
Authors: Wang Xue , Zhu Yinlian , Ma Xiuliang , Wang Can , Lu Huibin 
Published: August 2010

AbstractMicrostructures of BiFeO3 (BFO) thin films epitaxially grown on SrRuO3 (SRO) buffered SrTiO3 (STO) (001) substrates by laser molecular beam epitaxy were investigated by means of transmission electron microscopy (TEM). The results showed that the films grown under the oxygen pressures of 1Pa and 0.3Pa, respectively, contain parasitic phase embedded in the BFO phase. The parasitic phase was revealed to be poor in Bi and rich in Fe by high-angle annular dark-field (HAADF) imaging and energy dispersive X-ray spectroscopy (EDS) compositional analysis. In combination with selected area electron diffraction patterns, the parasitic phase was determined to be α-Fe2O3. By lowering oxygen pressure, the density and the size of α-Fe2O3 phase increases whereas the regularity decreases. High resolution TEM images showed that approximately periodic misfit dislocations exist at the interface between the α-Fe2O3 phase and the BFO matrix, indicating that the α-Fe2O3 particles are semi-coherently embedded in the BFO films. Less misfit dislocations were detected at the interfaces between the BFO films and the SRO/STO substrates, implying that the misfit strains in the films may be fully relaxed by the formation of α-Fe2O3 phase.
Determination Factors of Strain-relaxed Complex Domain Structure observed in Thick Epitaxial pb(Zr,Ti)O3Films
Authors: Nakaki Hiroshi , Utsugi Satoru , Fujisawa Takashi , Nakajima Mitsumasa , Ehara Yoshitaka , Yamada Tomoaki , Morioka Hitoshi , Ifuku Toshihiro , Funakubo Hiroshi 
Published: August 2010

AbstractCrystal structure change with the temperature was investigated for 3 m-thick (100)/(001)-oriented epitaxial PbTiO3 films grown on SrTiO3 substrates. Complex strain-relaxed domain structure labeled as Type III was observed and directly transformed to the cubic phase at about 490°C. This transition temperature and the lattice parameter (a and c- axes) change with the temperature well agreed with the reported data for the PbTiO3 powders. The volume fraction of the (001) orientations, Vc, was almost independent of the temperature up to the phase transition temperature. The tilting angles of the spots in XRD plan view were almost the same with the estimated ones from the lattice parameters and the Vc. This suggests that the angle of the domains identified by the domain structure in Type III. This structure is mainly determined by the tetragonality, (c/a ratio) and the Vc.
Development of Ferroelectric Data Storage Test System for High-Density and High-speed Read/Write
Authors: Hiranaga Yoshiomi , Tanaka Kenkou , Uda Tomoya , Kurihashi Yuichi , Kimoto Yasuhiro , Tochishita Hikari , Kadota Michio , Cho Yasuo 
Published: August 2010

AbstractIn this study, we have developed ferroelectric data storage test systems based on scanning nonlinear dielectric microscopy (SNDM) to conduct various experiments concerning read/write capability. Nanodomain formation on ferroelectric recording media was studied using the data storage test system. A nanodomain dot array was successfully written on a single-crystal LiTaO3 recording medium. The diameter of the written dot was as small as 7 nm. Epitaxial-thin-film LiTaO3 recording media were also developed. Nanodomain dots with the diameter of 25 nm were written on the thin-film recording medium. In addition, a non-contact probe-height control technique was adopted to solve the problem of tip abrasion using higher-order nonlinear dielectric response detection method. Finally, a hard-disk-drive (HDD)-type ferroelectric data storage test system was developed for conducting read/write tests under conditions close to those of actual operation. Capabilities of reading at the bit rate of 2 Mbps and writing at the bit rate of 20 Mbps were confirmed using the HDD-type data storage test system.
The Average Valence Electron Number: Is it a relevant parameter for Ni2MnGa Alloys?
Authors: Neumann Kristin , Elmashai Khaled , Hickel Tilmann , Neumann Klaus-Ulrich , Ouladdiaf Bachir , Ziebeck Kurt 
Published: August 2010

AbstractThe influence is investigated of the average valence electron number on the systematic changes of a Ni2MnGa based alloy series. The experimental investigation focuses on an isoelectronic alloy series Ni2Mnx(CrFe)1-x/2Ga for which the average valence electron number is unchanged for any value of x. Based on the changes of physical properties of alloys in this series compared to Ni2MnGa it is argued that local lattice distortions are more relevant for driving the change in alloy characteristics, such as the martensitic phase transition temperature or the ferromagnetic ordering temperature, than the band filling by valence electrons.
Purification and Functionalization of Diamond Nanopowders
Authors: Lim Jong-Kwan , Baek Jong-Beom 
Published: August 2010

AbstractPurification of diamond nanopowder (DNP) was conducted in a less-destructive mild polyphosphoric acid (PPA)/phosphorous pentoxide (P2O5). The wide-angle X-ray diffraction (XRD) showed that the intensity of the characteristic diamond d-spacing (111) at 2.07 Å from purified DNP (PDNP) was fairly increased compared to pristine DNP, indicating that significant amount of carbonaceous impurities were removed. Chemical modification of pristine DNP and PDNP with 4-ethylbenzoic acid was carried out to afford 4-ethylbenzoyl-functionalized DNP (EBA-g-DNP) and PDNP (EBA-g-PDNP). The morphologies of EBA-g-DNP and EBA-g-PDNP from scanning electron microscopy (SEM) were further affirmed the feasibility of chemical modification. The results suggested that the reaction condition was indeed viable for the one-pot purification and functionalization of DNP. The resultant functionalized DNP could be useful for nanoscale additives. Hence, EBA-g-DNP and EBA-g-PDNP was brominated by using N-bromosuccinimide (NBS). The resultant N-brominated DNP and PDNP could be used as initiator for the atom transfer radical polymerization (ATRP) to introduce many polymers onto the surface of functionalized DNP and PDNP.
Nanocoating on Carbon Nanofibers by Plasma Polymerization of Ethylene Gas
Authors: Hernández-Hernández Ernesto , Neira-Velázquez María Guadalupe , Ramos-de Valle Luis Francisco , Ponce Arturo , Sánchez-Anguiano María Guadalupe 
Published: August 2010

AbstractEthylene gas was used to modify the surface of carbon nanofibers (CNFs) by plasma polymerization. The modified CNFs were characterized by Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, dispersion test in chloroform and high resolution transmission electron microscopy (HRTEM).The results of dispersion test in chloroform showed that the plasma treatment promoted a stable dispersion of the treated nanofibers in the solvent. The FTIR results indicated that an organic polymer was deposited on the surface of the CNFs, and the Raman spectra showed evidence of the chemical interaction between the nanofibers and the polyethylene (PE) deposited by plasma. The presence of the thin polymer coating on the surface of CNFs was confirmed by HRTEM.
Microparticle filtration using carbon nanotubes and impedance characterisation for gold microelectrodes sensor system
Authors: Mathur Ashish , Hamad Eyad M , Mukhopadhyay Subhadeep , Sinha Roy Susanta , McLaughlin Jim A 
Published: August 2010

AbstractBlood-cell-free serum is required for most clinical chemistry tests. At present bend micro channel and polymeric pillars are used in polymer based microfluidic devices (such as PMMA) for the blood filtration. In this study, we have fabricated carbon nanotube (CNT) pillars on silicon from 20-50 μm in diameter with ˜10 μm spacing and integrate them inside the microfluidic channel with a view of using these for blood plasma filtration from whole blood, with passive capillary flow. Our main objective is to design a novel sensor, comprising CNT arrays, to filter/control whole blood flow, with an integrated micro patterned gold electrode which will be sealed by bonding into microfluidics structures. We have characterized the microfluidic channel by measuring the meniscus movement profiles. Also gold inter-digitated electrodes (IDEs) were fabricated on glass and immobilized with an antibody. These IDEs were used as an impedance-based biosensor using label-free antigen – antibody interaction. At a fixed frequency, the IDEs gave a linear response across the range of concentrations of secondary antibodies investigated (0 to 500 μg/mL).
Analysis of Tunnel Junction Suitable for 4000 Suns in Tandem High Efficiency Solar Cell Structures
Authors: Jung Donggeun , Carlin Conrad Zachary , Hauser John R. , Bedair Salah M. 
Published: August 2010

AbstractThe road to achieve ultra high efficiency is through multi-junction solar cells operating at high solar concentrations, larger than 1000 suns. Critical to the success of this approach is the development of tunnel junctions (TJ) that serve as electrically low loss interconnections, yet are optically transparent, using high band gap semiconductor material systems. We have previously reported the fabrication of a TJ made of n+-InGaP/ p+-AlGaAs with a band gap about 1.9 eV using Se and C doping, respectively. This TJ structure has a peak current density of 88 A/cm2 allowing it to be implemented in a three junction cell structure at solar concentrations as high as 4000 suns (x4000). Almost all reported conversion efficiencies higher than 40% have used this tunnel junction. This very high peak current density is unexpected in a high band gap material system, which is good news for the multi junction solar community. This seems to be due to the fact that the InGaP/AlGaAs interface has a staggered band line up. We will present the effect of this band line up at the heterointerface and its effect on the width of the depletion region and the peak current density. We also compare the current result from this heterostructure junction with an artificial homojunction made of n+-AlGaAs/ p+-AlGaAs doped to the same levels as that of the heterojunction. Results from the homojunction showed that peak current density is about one half of that obtained from the heterojunction at the same doping levels. A reasonable match between experimental result and the model was obtained when a value of 150 meV was used for ΔEc, the conduction band discontinuity at the interface. Both experiment and theory predicted that at a current density of about 80 A/cm2 with only about a few tens of meV drop across the TJ. This will have a minimal effect on the overall efficiency of the tandem solar cell structure when used at high solar concentrations.
Raman and Rutherford Backscattering Characterization of Ti-implanted Si above the Mott Limit
Authors: Olea Ariza Javier , Pastor David , Mártil Ignacio , González-Díaz Germán , Ibáñez Jordi , Cuscó Ramón , Artús Luis 
Published: August 2010

AbstractWe have analyzed the degree of crystalline lattice recovery in samples implanted with Ti concentrations well above the Mott limit and subsequently Pulsed-Laser Melting (PLM) annealed by means of Raman spectroscopy and Rutherford Backscattering Spectroscopy (RBS). Since very recently, theoretical studies predicted Ti interstitial sites for the Intermediate Band (IB) formation, the knowledge of the Ti impurity lattice location after PLM annealing is an essential point that can be elucidated by means of RBS measurements. After PLM annealings, Raman and RBS measurements have shown a decrease in the lattice crystalline quality as implanted dose is increased, yielding a significantly improvement of the lattice quality at the highest energy density studied. The RBS channeling spectra show that after PLM annealings Ti impurities are mostly occupying interstitial lattice sites.
Strength of Multicrystalline Silicon Wafers for Various Surface Conditions
Authors: Rupnowski Przemyslaw , Sopori Bhushan , Armentrout Dan , Good Ethan 
Published: August 2010

AbstractThis study focuses on fracture properties of silicon wafers used by the photovoltaic (PV) industry as substrates for solar cells. In the first part, we numerically model three fixtures that are often used to test the strength of PV wafers. In the second part, we employ our previously developed model to predict strength of the wafers as a function of loading fixture and surface treatment. Surface treatment is simulated by removing damage from the wafer surface.
Evaluating Amorphization Around Micro-Cracks in PV Silicon
Authors: Kulshreshtha Prashant K. , Youssef Khaled M. , Rozgonyi George 
Published: August 2010

AbstractSince the initiation and propagation of a micro-crack in a silicon wafer introduces local variations in stress, it is critical to the understanding of wafer breakage that accurate profiling of stress be performed in the vicinity of the micro-crack. In this study, nanoindentation has been used to investigate the stress-relaxation during crack initiation and propagation in material of particular interest to the photovoltaic (PV) industry. The low load (<1 mN) capability of a Hysitron Triboindenter® was used to accurately profile the extent of plastic deformation and resulting amorphization. Measurements were made on Si samples extracted from top, middle and bottom of a (100) oriented single crystal ingot to evaluate the impact of different carbon, oxygen and metallic impurity concentrations. A gradual but significant drop in hardness from 10.2 to 6.9 GPa occurred as indents were made closer to the micro-crack and was attributed to local amorphization. Electron back scattered diffraction (EBSD) and Raman spectroscopy confirmed the amorphization, respectively, at nano- and micro-scale.
Inherent Buffer-layer Formation on Chalcopyrite Absorbers
Authors: Pettenkofer Christian , Hofmann Andreas , Lehmann Carsten , Dombrowa Alexandra 
Published: August 2010

AbstractWe report on epitaxial growth of ZnO on polycrystalline and (112) orientated CuInS2 and CuInSe2 thin films. Step-by-step growth and investigation by photoelectron spectroscopy (PES) and low energy electron diffraction (LEED) provided information on the growth mode and the electronic structure of the ZnO-CuInS2-interface. During the initial growth no ZnO is deposited. Instead a monolayer of ZnS is formed by depletion the CuInS2 surface of excess sulfur. Thereafter, the ZnO growth starts on the ZnS buffer layer. The band alignment derived from PES shows that the ZnS buffer layer is thin enough to provide a beneficial band alignment for photovoltaic applications. CuInSe2 (112) samples showed a similar behaviour, but at the chosen deposition temperature of 450°C only ZnSe growth is detected. At lower temperatures ZnO growth on top of ZnSe is observed. XPEEM experiments show an inhomogeneous interface.
Lower Temperature Si Thin Films by Metal Induced Growth for Lower Cost Solar Cells
Authors: Mersich Peter T , Anderson Wayne A , Giese Rossman F 
Published: August 2010

AbstractMetal induced growth (MIG) was used to form epitaxial thin films of microcrystalline Si (μc-Si). By substituting Al as the catalyst metal in place of the usual Ni, x-ray diffraction (XRD) confirmed that μc-Si was successfully grown at temperatures between 350-525°C. At 525°C, a preferred orientation of (220) Si was observed with additional (111) and (311) Si orientations, while a temperature of 350°C resulted in a shift in preferred orientation to (111) Si. The lower limit for Al thickness was found to be between 10-20 nm with little crystallization and a smooth surface observed at 10 nm with XRD and SEM, respectively. Electrical measurements on Schottky diodes revealed space-charge limited conduction (SCLC) with an exponential distribution of trap levels due to diffusion of Al atoms into the Si, which was supported by analysis with energy dispersive x-ray spectroscopy (EDX) near the film surface. By depositing a thin layer of Co on top of Al prior to sputtering, the films exhibited increased crystallinity and a more uniform surface likely due to increased confinement of Al atoms. Electrical measurements demonstrated a shift from SCLC to thermionic emission in resulting Schottky diodes.
Enabling High-Throughput, Low-Cost Manufacturing of OLED Display and Lighting Panels
Authors: Long Michael , Koppe Bruce E , Redden Neil P , Boroson Michael L , Hatwar Tukaram K , Hamer John W 
Published: August 2010

AbstractLarge-scale manufacturing of organic light-emitting diode (OLED) panels for lighting and display has been slowed by several manufacturing factors, prominent among which are low throughput due in part to the fine metal mask technology for patterning the red-, green-, and blue-light-emitting pixels and low materials utilization efficiency of the available vacuum deposition technology. To overcome these impediments to low-cost OLED manufacturing, Kodak developed a blanket white-emitting OLED architecture in combination with a pixilated color filter array to eliminate the need for fine metal masks and developed a vacuum deposition technology capable of high deposition rates and high materials utilization efficiency. These developments, taken together, allow much higher throughput and yield on fifth-generation and larger substrates that promise to enable low-cost manufacturing of OLED displays and lighting panels. This paper focuses on the deposition technology Kodak developed, a flash vaporization process that can deliver very high materials utilization efficiency at high deposition rates for small-molecule OLED materials without increasing material decomposition.
Mechanisms of Radiation Damage and Properties of Nuclear Materials
Authors: Lumpkin Gregory R. , Smith Kath , Whittle Karl , Thomas Bronwyn S. , Marks Nigel A. 
Published: August 2010

AbstractRadiation damage effects in ceramics, e.g., nuclear waste forms, transmutation targets, and inert matrix fuels, may have important implications for the physical and chemical stability of these materials as the cumulative radiation dose increases over time. A key aspect of scientific research in this area is the ability to understand the fundamental damage mechanisms through the combination of experimental and atomistic modelling techniques. In this paper, we review some of the lessons learned from the significant body of data now available for pyrochlore-defect fluorite based materials, followed by an illustration of the advantages of working on simple compounds with well established interatomic potentials. We conclude the paper with a description of radiation damage processes in the LaxSr1-1.5xTiO3 defect perovskites, a system that includes phase transformations, short-range order effects, and complex defect behavior.
How to Simulate the Microstructure Induced by a Nuclear Reactor with an Ion Beam Facility : DART
Authors: Luneville Laurence , Simeone David , Baldinozzi Gianguido , Gosset Dominique , serruys yves 
Published: August 2010

AbstractEven if the Binary Collision Approximation does not take into account relaxation processes at the end of the displacement cascade, the amount of displaced atoms calculated within this framework can be used to compare damages induced by different facilities like pressurized water reactors (PWR), fast breeder reactors (FBR), high temperature reactors (HTR) and ion beam facilities on a defined material. In this paper, a formalism is presented to evaluate the displacement cross-sections pointing out the effect of the anisotropy of nuclear reactions. From this formalism, the impact of fast neutrons (with a kinetic energy En superior to 1 MeV) is accurately described. This point allows calculating accurately the displacement per atom rates as well as primary and weighted recoil spectra. Such spectra provide useful information to select masses and energies of ions to perform realistic experiments in ion beam facilities.
Evaluation of Adhesive Strength of Oxide Layer on Carbon Steel at Elevated Temperatures
Authors: Satou Manabu 
Published: August 2010

AbstractAdhesive strength of the oxidation layers on carbon steel was evaluated by means of a laser shock method, which uses a pulsed laser to generate shock wave. Oxidation for 200 hours in air created 10-micron-thick magnetite on carbon steel. Typical strength of the layer was evaluated to be about 50MPa at ambient temperature. The adhesive strength was varied from around one-tenth of yield stress to the ultimate tensile strength of the base materials. The adhesive strength of the oxide layer depended on test temperature. It is possible that the adhesive strength becomes an essential parameter for the evaluation of the protective layers.
Grain Boundary Characteristics Evaluation by Atomistic Investigation Methods
Authors: Kaji Yoshiyuki , Tsuru Tomohito , Shibutani Yoji 
Published: August 2010

AbstractThe grain boundary has been recognized for one of the major defect structures in determining the material strength. It is increasingly important to understand the individual characteristics of various types of grain boundaries due to the recent advances in material miniaturization technique.In the present study three types of grain boundaries of coincidence site lattice (CSL), small angle (SA), and random types are considered as the representative example of grain boundaries. The grain boundary energies and atomic configurations of CSL are first evaluated by first-principle density functional theory (DFT) and the embedded atom method (EAM) calculations. SA and random grain boundaries are subsequently constructed by the same EAM and the fundamental characteristics are investigated by the discrete dislocation mechanics models and the Voronoi polyhedral computational geometric method. As the result, it is found that the local structures are well accorded with the previously reported high resolution-transmission electron microscope (HR-TEM) observations, and that stress distributions of CSL and SA grain boundaries are localized around the grain boundary core. The random grain boundary shows extremely heterogeneous core structures including a lot of pentagon-shaped Voronoi polyhedral resulting from the amorphous-like structure.
The Lifetime of Polar-Optical Modes in Semiconductors
Authors: Ridley Brian K , Dyson Angela 
Published: August 2010

AbstractAn enduring problem in the engineering of high-power semiconductor devices is how to mitigate the effect of heating. Heating means the proliferation of phonons, and phonons, interacting with electrons directly affect the electronic performance of the device. Nowhere is this more evident than the role of hot polar-optical phonons in reducing the drift velocity in the channel of an HFET and hence reducing its performance at high frequencies. The task of describing hot-phonon effects is complicated by the coupling to plasma modes. We present a theory of coupled plasmon-phonon modes in GaN, how they interact with electrons and how their lifetime becomes density-dependent. Raman scattering in bulk material shows a reduction of lifetime with increasing density and we offer an explanation for this in terms of the frequency dependence of the anharmonic decay mechanism. Hot-phonon effects, however, involve modes with wave-vectors beyond those probed by Raman scattering. By adopting a single-pole approximation for these modes we have obtained the lifetime dependence on wave vector, electron temperature and density.