bluuebunny/crossref_metadata_2025 huggingface dataset:
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

Oxide 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

Present 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

Vanadium 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

The 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.
The effect of Ni-substitution on physical Properties of Fe72-xB24Nb4Nix Bulk Metallic Glassy Alloys
Authors: Masood Ansar , Biswas Anis , Ström V. , Belova L. , Ågren J. , Rao K. V.
Published: April 2011

We have succeeded in producing bulk metallic glass by partial substitution of Fe with Ni in Fe-B-Nb alloys which could otherwise be only melt spun into amorphous ribbons. Substitution by Ni in the Fe72-xB24Nb4Nix alloys with (x ~2, 4, 6, 8, 10, 12 and 14) improves the glass forming ability of the materials and as a result rods of same compositions can be fabricated. Magnetically the BMG alloys remain soft with coercitivities below 500 mOe- However, the electrical resistivity of the system decreases significantly by as much as a factor of two with the increase of Ni concentration, and becomes more metallic like with a positive temperature coefficient.
Time-of-Flight Characterization of Single-crystalline CVD Diamond with Different Surface Passivation Layers
Authors: Kovi Kiran Kumar , Majdi Saman , Gabrysch Markus , Friel Ian , Balmer Richard , Isberg Jan
Published: April 2011

The electronic properties of diamond, e.g. a high band-gap and high carrier mobilities, together with material properties such as a very high thermal conductivity, chemical inertness and a high radiation resistance makes diamond a unique material for many extreme electronic applications out of reach for silicon devices. This includes, e.g. microwave power devices, power devices and high temperature electronics. It is important to have an effective passivation of the surface of such devices since the passivation determines the ability of the device to withstand high surface electric fields. In addition, the passivation is used to control the surface charge which can strongly influence the electric field in the bulk of the device. It is possible to measure sample parameters such as electron and hole drift mobilities, charge carrier lifetimes or saturation velocities using Time-of-flight (ToF) method. The ToF technique has also been adapted for probing the electric field distribution and the distribution of trapped charge. In this paper we present new data from lateral ToF studies of high-purity single crystalline diamond with different surface passivations. Silicon oxide and silicon nitride are used as passivation layers in the current study. The effect of the passivation on charge transport is studied, and the results of different passivation materials are compared experimentally.
Alloying Effects on the Stability of γ/γ′ Microstructure in Co-Al-W Base Alloys
Authors: Tsukamoto Yuki , Kobayashi Satoru , Takasugi Takayuki
Published: April 2011

The aim of this study is two-fold: first we reexamine the thermodynamic stability of γ’-Co3(Al,W) phase in the Co-Al-W ternary system. Secondly, we investigate the effect of a fourth alloying element (Ti or Ta) on the thermodynamic stability of the γ’ phase through microstructure observation, DSC measurement and EPMA analysis. Coarsened areas with γ/CoAl/Co3W phases are formed after annealing at 900 ºC for 2000 h in Co-Al-W ternary alloys with different Al/W ratios, which confirms that the three phases are in equilibrium with each other and that the γ’ phase is metastable at this temperature. The addition of a fourth alloying elements does not drastically change the microstructure formed after long term annealing at 900 ºC, indicating that the alloying elements do not improve the stability of the γ’ phase.
Comparison of Different Fluorine-treatments for Improved High Temperature Oxidation Resistance of TiAl-alloys
Authors: Donchev A. , Schütze M. , Kolitsch A. , Yankov R.
Published: April 2011

Intermetallic TiAl-alloys can replace the heavier Ni-based superalloys in several high temperature applications with regards to their mechanical properties, however they can not be used at temperatures above 800°C in oxidizing environments for longer times because of insufficient oxidation resistance. Despite an Al-content of about 45 at.% in technical alloys, no protective alumina layer is formed because the thermodynamic stabilities of titanium oxide and aluminum oxide are of the same order of magnitude. Therefore a mixed TiO2/Al2O3-scale is formed which is fast growing so that the metal consumption rate is quite high. On the other hand the formation of a slow growing alumina layer is promoted by a fluorine treatment. This so called fluorine effect leads to the preferential intermediate formation of gaseous aluminum fluorides at elevated temperatures if the fluorine content at the surface stays within a defined concentration range. These fluorides are converted into solid Al2O3 due to the high oxygen partial pressure of the high temperature service environment forming a protective pure Al2O3 surface scale. In this paper results of high temperature oxidations tests of several technical TiAl-alloys will be presented. Different F-treatments e.g. dipping or spaying which are easy to apply have been used and their results will be compared. The mass change data of the F-treated specimens are always lower than those of the untreated ones. Post experimental investigations such as light microscopy, scanning electron microscopy and energy dispersive X-ray analysis reveal the formation of a thin alumina layer on the F-treated samples after optimization of the process while a thick mixed scale is found on the untreated samples. The results will be discussed in view of an optimized procedure and the future use of TiAl-components in high temperature environments.
Atom probe tomography analysis of Ti-Y-O clustering during processing of nanoscale oxide particles in 14%Cr ODS ferritic steels
Authors: Williams Ceri A. , Unifantowicz Paulina , Oksiuta Zbigniew , Baluc Nadine , Smith George D. W. , Marquis Emmanuelle A.
Published: April 2011

Atom probe tomography is used to investigate the clustering of Y-Ti-O in a 14%Cr-2%W-0.3%Ti & 0.3% Y2O3 ODS steel. The clusters in the consolidated material are compared to clusters observed in the powder prior to consolidation. A higher density of smaller clusters is observed in the powder, and the clusters are found to contain more O and less Y.
SOI Waveguide Optical Nonreciprocal Devices with Directly Bonded Garnet
Authors: Mizumoto Tetsuya , Takei Ryohei
Published: April 2011

Surface activated direct bonding of a magnetooptic garnet crystal to a Silicon-On-Insulator (SOI) wafer is discussed for the application to waveguide optical nonreciprocal devices. An interferometric waveguide isolator is discussed that uses nonreciprocal phase shift brought about by a first-order magneto-optic effect. In an SOI waveguide, the low refractive index of buried oxide layer enhances the magneto-optic phase shift. This contributes to reduce the device size together with the strong field confinement of high index contrast waveguide. The interferometric isolator can be extended to an optical circulator by adopting appropriate 3-dB directional couplers to construct a Mach-Zehnder interferometer.
Hard magnetic materials based on Nd9(Fe,B)87Zr2Nb2 nanograined intermetallic compounds
Authors: Kumon Shoichi , Nishimoto Kazue , Fukuzaki Tomokazu , Tamura Ryuji
Published: April 2011

Magnetization behavior of Nd9(Fe, B)87Zr2Nb2 nanostructure magnets have been investigated. We will show that the nanostructure magnets are composed of magnetic clusters of exchange-coupled single domains and the coercivity is governed by coupling intensity between soft and hard magnetic clusters in the magnets.
Microfracture Test of Mg12ZnY Intermetallic Compound in Mg-Zn-Y Alloys
Authors: Yoshimura Hajime , Matsuyama Shun , Matsuda Mitsuhiro , Otsu Masaaki , Takashima Kazuki , Kawamura Yoshihito
Published: April 2011

A Mg-Zn-Y alloy including a Mg12ZnY intermetallic compound exhibits excellent mechanical properties as compared to conventional magnesium alloys. The superior mechanical properties of this alloy seem to originate from the Mg12ZnY intermetallic compound; however, the mechanical properties of Mg12ZnY itself have not yet been fully investigated owing to the small size of this compound. In this study, a microfracture test was performed to investigate the fracture properties of the Mg12ZnY intermetallic compound. The material used in this test was a Mg88Zn5Y7 alloy. Micro-sized cantilever specimens composed of Mg12ZnY, with dimensions of 10 × 20 × 50 μm3, were prepared selectively isolated from the Mg88Zn5Y7 alloy using focused ion beam (FIB) machining. Notches with a width of 0.5 μm and a depth of 5 μm were also introduced into the micro-sized specimens. Microfracture tests were performed using a mechanical testing machine for microscale materials. The fracture toughness values (KQ) of Mg12ZnY were 1.2−3.0 MPam1/2. TEM observations indicated that the KQ values were dependent on the crack orientation in Mg12ZnY, with the higher KQ values correlating with cracks propagating parallel to the c-axis of Mg12ZnY. This suggests that the fracture toughness of Mg-Zn-Y alloys can be improved by controlling the orientation of the Mg12ZnY compound.
Quarternary and Quinary Additions to Directionally-Solidified X-X3Si Eutectics of Chromium and Vanadium
Authors: Ang J , Vorontsov VA , Hayward CL , Balakrishnan G , Stone HJ , Rae CMF
Published: April 2011

An alternative high temperature structural alloy system based on the X-X3Si eutectic compositions of chromium and vanadium is put forward. These low-density (~6g/cm3) eutectics have a bcc solid-solution to increase alloy fracture toughness, and a A15 X3Si as the high temperature load-bearing phase. (½Cr,½V)-(½Cr,½V)3Si was used as the base alloy for further element additions, and is represented by the symbol 山 10at.% tantalum and aluminium were substituted for vanadium as quaternary and quinary alloy additions.

Microstructure, elemental phase partitioning, compression creep and oxidation results will be discussed. Cr-Cr3Si has a tidy, fine lamellar microstructure. Vanadium coarsens and destabilises the lamellae to a limited extent. Tantalum addition causes two distinct populations of eutectic to form; one population having finer lamellae than the other. Aluminium does not coarsen or destabilise the lamellar microstructure. High temperature compression tests at 1200°C and 1300°C show that 山 is stronger than the binary alloys, and of similar strength to the quaternary and quinary alloys.
‘In-situ’ Solution Processed Room Temperature Ferromagnetic MgO Thin Films Printed by Inkjet Technique
Authors: Wu Yan , Zhan Yiqiang , Fahlman Mats , Fang Mei , Rao K. V. , Belova Lyubov
Published: April 2011

We report on ‘in-situ’ solution processed homogeneous (200) oriented MgO ~85nm thin films deposited on Si substrates by inkjet printing. These films are found to show ferromagnetic order beyond room temperature with a saturation magnetization MS as high as ~0.63 emu/g. X-ray photoelectron spectroscopy investigations show the absence of any possible contamination effects, while the Mg 2p, and O 1s spectra indicate that the role of defect structure at the Mg site is important in the observed magnetism. By controlling the pH values of the precursors the concentration of the defects can be varied and hence tune the magnetization at room temperature. The origin of magnetism in these MgO thin films appears to arise from the cation vacancies.
Radiation damage studies of nuclear ceramics using the JANNUS-Saclay triple -ion beam irradiation platform
Authors: Trocellier P. , Miro S. , Serruys Y. , Bordas É. , Martin H. , Chaâbane N. , Pellegrino S. , Vaubaillon S. , Gallien J.P.
Published: April 2011

The third accelerator of the multi-ion irradiation platform JANNUS (Joint Accelerators for Nanosciences and NUclear Simulation), a 6SDH-2 Pelletron from National Electrostatic Corporation, Middleton was installed at Saclay in October 2009. The first triple beam irradiation combining Fe, He and H ion beams has been performed in March 2010 on a Fe-12Cr model ODS alloy. In the first part of this paper, we give a technical description of the triple beam facility. Then, we present its performances and experimental capabilities. Typically, damage dose up to 100 dpa can be reached in 10 hours irradiation with heavy ion beams, with or without simultaneous bombardment by protons, helium-4 ions or any other heavy ion beam. In the second part of this paper, we illustrate some recent experiments relative to advanced nuclear ceramics and composite materials developed in the frame of the Generation IV Forum research program or for fusion applications.
Fabrication of Low Cost 1D CdSe Nanowires using Near-field Electrospinning
Authors: Magwood Leroy , Starly Binil
Published: April 2011

Well-aligned, 1D CdSe quantum dot (QD) fibers (0.3μm to 2.5μm) containing up to 20wt% fluorescent quantum dots (QDs) were prepared by near-field electrospinning (NFES) process. Electrospun solutions were prepared using PVAc as the matrix polymer, dimethyl formamide (DMF) solvent and colloidal QDs in chloroform (CHCl3). The diameter of the fibers decreased as the ratio of DMF/CHCl3 is varied. QDs showed good dispersion and a linear relationship between QD loading and fiber diameter, as determined by the morphology measurements taken using TEM and SEM, respectively. Fluorescence microscopy shows that there is light attenuation throughout the fibers. Results also show that the NFES process may be used as a method to create aligned, 1D fibers of QDs and potentially other nanofibers.
Microstructure and Oxidation Resistance of Cr-Ta-Si alloys
Authors: Bhowmik Ayan , Pang Hon Tong , Neumeier Steffen , Stone Howard J. , Edmonds Ian
Published: April 2011

The phase equilibria and oxidation resistance of alloys lying near the Cr-rich end of the Cr- Ta-Si system have been investigated. Samples were prepared by arc-melting and homogenized at 1300°C for 500hrs. Identification of the phases present and their compositions were carried out using x-ray diffraction and electron probe micro-analysis and the ternary phase diagram on the Cr-rich end was plotted. A three-phase equilibria was found to exist between an A2 Cr-solid solution, a hexagonal Laves phase and the A15 Cr3Si intermetallic phase for alloys with higher contents of Si.Thermo-gravimetric analysis of the alloys at 1100°C demonstrated an improvement in the oxidation resistance of the ternary alloys with increasing Si-content. The microstructures of the oxidized samples revealed the formation of a thick chromia layer on top of a Cr,Ta-mixed oxide layer and an internal oxidation zone for all the alloys. A protective silica layer was not observed to form in any of the alloys tested.
Pseudoelasticity of D03-Type Fe3Al and Fe3Ga-Based Alloys
Authors: Yasuda Hiroyuki Y. , Umakoshi Yukichi
Published: April 2011

The pseudoelastic behavior of Fe3Al and Fe3Ga alloys with the D03 structure is reviewed. In general, pseudoelasticity of shape memory alloys is based on a thermoelastic martensitic transformation. However, pseudoelasticity regardless of the martensitic transformation is found to take place in D03-ordered Fe3Al and Fe3Ga alloys. For instance, a 1/4<111> superpartial dislocation in Fe3Al alloys moves independently dragging an antiphase boundary (APB). During unloading, the APB pulls back the superpartial to decrease its energy resulting in pseudoelasticity, which is called “APB pseudoelasticity”. Moreover, D03-type Fe3Ga alloys were found to demonstrate three types of pseudoelasticity based on the dislocation motion, twinning and martensitic transformation depending on the chemical composition, degree of D03 order, loading axis, stress sense and deformation temperature. The mechanism of the pseudoelasticities in the D03-type intermetallics is discussed based on some in situ observations. The effects of chemical composition, deformation temperature and crystal orientation on the pseudoelastic behaviors are also discussed.
Irradiation behaviour of Precipitation Hardened Ni-base Super-alloys with EHP Grade under Multi-ion Irradiation
Authors: Kim Gwang-Ho , Shiba Kiyoyuki , Sawai Tomotsugu , Ioka Ikuo , Kiuchi Kiyoshi
Published: April 2011

The irradiation behaviour in two different precipitation hardening types of Ni-base alloys with the ultra high purity grade (EHP), namely, the γ’ type and G phase type was investigated by multi-ion beam techniques simulated to the irradiation conditions in fuel cladding tubes used in sodium cooled FBRs. Single ion-beam irradiation tests were conducted up to 90 dpa (by Fe3+ or Ni3+) at 673 K. Triple ion-beam irradiation tests were conducted up to 90 dpa (by Ni3+, 90 appmHe and 1350 appmH) at 823K. The irradiation behaviour was examined by and the microscopic observation by TEM to the distribution of dislocations, cavities and voids. The behaviour was compared with those of PNC316. The dominating irradiation defects in EHP(γ’) alloy at 673 K by single ion-beam are Frank loops, perfect unfaulted loops and line dislocations. Whereas, those of EHP(WSi) alloy are the irradiation-induced γ’ (Ni3Si) precipitates along {111} planes. Those dominating defect structures at 823 K by triple ion-beam are classified as followings, bimodal distributions in EHP(γ’), bubbles in EHP(WSi) and voids in PNC316. From those results, the excellent irradiation properties of EHP(WSi) alloy is clarified as the inhibition effects of secondary irradiation defects.
Mechanical and Electrical Properties of Rapidly Solidified Cu-Zr-Ag Alloy Fabricated by Powder Rolling Process
Authors: Miyakawa Satoru , Nishida Motonori , Nishiyama Nobuyuki , Miura Haruko , Inoue Akihisa
Published: April 2011

A non-equilibrium Cu-Zr-Ag alloy was designed for the development of an alternative electric connector to Cu-Be alloys. This work aims at producing a Cu-Zr-Ag sheet using a hot-powder-rolling (HPR) process. The sheets were produced by a sequential process of HPR, pre-annealing, and cold rolling, using Cu93.5Zr5.5Ag1 (at.%) alloy powder produced by an argon gas atomization method. The Cu93.5Zr5.5Ag1 alloy sheet has a tensile strength of 1188 MPa and a conductivity of 33.2% IACS, which are similar values to those of Cu-Be alloys. In this paper, we optimize the conditions of the HPR process and reveal the correlation between the microstructure and properties of the Cu-Zr-Ag sheet produced by the HPR process. In addition, we discuss the alloy’s applicability for use as a connecter material.
Both Luminous Efficiency and Lifetime Enhancement in Blue
Fluorescence OLEDs by Modifying Molecular Structure of Hole Transporting
Material
Authors: Kwak Yoonhyun , Lee Sun-Young , Jeong Hye-In , Shin Dae-Yup , Song Young-Woo , Lee Jong Hyuk , Kim Sung Chul
Published: April 2011

Both luminous efficiency and lifetime in blue fluorescence organic light
emitting devices (OLEDs) have been improved by modified HTMs with higher
LUMO energy levels. The LUMO energy levels of HTM were increased by
modifying substituent in HTM molecules. Two HTMs containing ortho and meta
biphenyl substituent and one HTM containing thiophene substituent were
synthesized via palladium catalyzed amine coupling reactions to compare with
a para biphenyl substituent HTM-1 as a standard molecule. According to TDDFT
calculations, these three modified HTMs showed 0.05-0.15 eV higher LUMO
energy levels compared to the para biphenyl substituent HTM-1. The luminous
efficiency and the lifetime (LT90) of OLEDs using HTM-2 at 500
cd/m2 have been enhanced up to 20 % and 52 %, respectively,
compared to the standard device using HTM-1.
Oxidation Response and Coatings for Mo-Si-B Alloys
Authors: Perepezko J. H. , Sakidja R.
Published: April 2011

Mo-Si-B alloys respond to high temperature oxidation in two distinct stages. First, there is a transient stage with an initial high recession rate that corresponds to the evaporation of volatile MoO3 due to the oxidation of the molybdenum rich phases. The steady state stage of the oxidation begins when a borosilica layer that initiated in the transient period becomes continuous and protects the alloy from further rapid oxidation. Then, the oxidation rate is limited by oxygen diffusion through the borosilicate layer. In order to improve the oxidation performance of the Mo-Si-B alloys, it is necessary to minimize the transient stage. The three phases, Mo (solid solution), Mo3Si (A15) and Mo5SiB2 (T2), composing the Mo-Si-B alloys play different roles in the transient stage. The interaction of the three phases with a reduced microstructure scale can reduce considerably the transient oxidation stage. As a further approach to inhibit the transient stage, a kinetic biasing strategy has been developed to capitalize on the reactions between different phases to develop useful reaction products and alloy compositions that evolve toward a steady state of a compatible system. In order to achieve a compatible interface coating together with enhanced oxidation resistance, a pack cementation process has been adopted to apply diffusion coatings. Two areas are highlighted for successful coating applications on Mo-Si-B alloys and robust high temperature oxidation resistance: development of metal-rich silicide + borosilicide high-temperature coating and in-situ thermal-barrier + borosilica coatings.
The Effect of Ge and Ti Additions on the Microstructures and Properties of Nb-18Si Based Alloys
Authors: Li Zifu , Tsakiropoulos Panos
Published: April 2011

The effects of Ge and Ti additions on the microstructure, hardness and oxidation behaviour of the alloys Nb–18Si–5Ge (ZF1) and Nb–24Ti–18Si–5Ge (ZF3) were studied. The as cast microstructure of the alloy ZF1 consisted of Nbss (cI2), and βNb5Si3 (tI32) with the latter being the primary phase and the two phases forming high volume fractions of Nbss + βNb5Si3 eutectic. The Ge addition stabilised the βNb5Si3 (tI32), and destabilised the Nb3Si (tP32) and the Nbss + Nb3Si eutectic. After heat treatment at 1200 °C for 100 h the βNb5Si3 (tI32) was partially transformed to the αNb5Si3 (tI32), and equilibrium was reached after heat treatment at 1500 °C for 100 h. The phases present in the as cast alloy ZF3 were the Nbss (cI2), and the Nb3Si (tP32), βNb5Si3 (tI32) and Ti5Si3 (hP16) silicides, with the latter forming a eutectic with the solid solution. The same phases were present after heat treatment at 1200 °C for 100 h but only the Nbss, and the Nb3Si and Nb5Si3 silicides were present after 100 h at 1500 °C where TiO2 was also formed. The Ge addition increased the microhardness of the Nb5Si3. The synergy of Ti with Ge resulted in a strong hardening effect and a remarkable retention of the hardness of the alloy ZF3. The additions of Ge and Ti to the Nb-18Si alloy improved the oxidation resistance at 800 °C, but pest oxidation behaviour was not eliminated.
Inkjet-printed PEDOT:PSS/SWCNTs on Paper: Substrate Effects on Conductivity
Authors: Angelo Peter D. , Farnood Ramin R.
Published: April 2011

Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate), or PEDOT:PSS, and single-walled carbon nanotubes (SWCNTs) were incorporated into an inkjet ink. The combination of PEDOT, a conjugated, conductive polymer, and highly conductive CNTs, yielded a conductive film after printing and curing of the ink. Several paper types were used as substrates for depositing printed patterns of the PEDOT:PSS/SWCNT ink. Wide variability in conductivity was observed for different commercial paper types, ranging from a maximum 0.9 S/cm on Epson® Premium Photo cast-coated glossy paper to 3 × 10-5 S/cm on Epson® Premium Presentation coated cardstock. Increasing the SWCNT content of the ink improved conductivity on a non-permeable cellulose acetate substrate to a point, after which the combined effects of ink filtration and jetting limited the number of nanotubes delivered to the substrate. On permeable paper, the irregularity of the substrate overcame the beneficial effects of SWCNTs as “bridges” between conductive PEDOT regions. Correlations between the substrates’ physical structure and conductivity were established for the printed sheets, with densely coated sheets presenting the highest conductivity, and porous sheets the lowest.
Direct observation of an ordered arrangement of vacancies and large local thermal vibration in rhenium silicide by Cs-corrected STEM
Authors: Harada Shunta , Tanaka Katsushi , Kishida Kyosuke , Okamoto Norihiko L , Endo Noriaki , Okunishi Eiji , Inui Haruyuki
Published: April 2011

The crystal structure of thermoelectric rhenium silicide with an ordered arrangement of vacancies is investigated by utilizing spherical aberration (Cs) corrected scanning transmission electron microscopy (STEM) combined with synchrotron X-ray diffraction and conventional transmission electron microscopy. By STEM Cs corrected imaging, we can clearly observe Si vacancies in rhenium silicide, which is impossible without Cs correction. In addition, significantly reduced contrast levels are noted in STEM images for particular Si sites near vacancies. From the STEM image simulation, the reduced contrast levels are concluded to be due to anomalously large local thermal vibration of these Si atoms. The crystal structure of rhenium silicide can be successfully refined by the synchrotron X-ray diffraction starting with the deduced structure model from the STEM images and the occurrence of large local thermal vibration can be qualitatively confirmed. Furthermore, we confirm the validity of the refined crystal structure of rhenium silicide by comparing experimental images with simulated image generating with the refined crystal structure parameters.
Mo Fiber Reinforced NiAl Composites Produced by Directional Solidification – Process, Microstructure and Mechanical Properties
Authors: Hu L. , Bogner S. , Hu W. , Bührig-Polaczek A. , Gottstein G.
Published: April 2011

Composites with a eutectic composition NiAl-9at.%Mo were produced by controlled directional solidification (DS) so that refractory metallic Mo fibers were precipitated and aligned in the NiAl matrix parallel to the solidification direction through the eutectic reaction. Such NiAl composites can be used for structural applications at high temperatures (> 1000 °C), for example as blade material for modern gas turbines. The microstructure of the composites was examined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The interface fine structure between Mo fiber and NiAl matrix was studied by high resolution TEM (HRTEM). Mechanical properties were measured by tensile tests at 700 °C and 1100 °C. Accordingly, a correlation of the DS parameters, microstructure and mechanical properties was established.
Local Stress-strain Structure in CVD Diamond Observed by Raman Peak-shift Mapping
Authors: Kato Yukako , Umezawa Hitoshi , Teraji Tokuyuki , Shikata Shin-ichi
Published: April 2011

Semiconductor epitaxial CVD single crystal diamond is considered a potential material for power devices because of its unique characteristics. In the discussion on the relationship between crystal quality and device performance, the atomic purity and defect concentration have been considered; however, the information on the local stress-strain distribution in a single crystal is not sufficient. In this paper, the local stress-strain distribution of the epitaxial CVD single crystal diamond is quantitatively examined using the birefringence and cathodoluminescence images and the Raman peak-shift map. From the Raman peak-shift map, the local stress-strain is estimated and the stress is found to range from -67 MPa to +160 MPa in the observed area.
The Li-adsorbed C(100)-(1x1):O Diamond Surface
Authors: O’Donnell Kane M. , Martin Tomas L. , Fox Neil A. , Cherns David
Published: April 2011

This paper presents density functional theory results for the Li-adsorbed C(100)-(1x1):O system. Previously it has been shown that at a single monolayer coverage, the binding energy for Li on oxygenated C(100) diamond is substantially higher than that of heavier alkali metals, while at the same time, the presence of the lithium generates a large shift in the diamond workfunction. The system is therefore promising for electronics applications involving diamond. Here, further calculations are presented showing that additional Li atoms above 1ML coverage are far less strongly bound, suggesting the 1ML surface is the most useful for vacuum microelectronic applications.
Determination of Boron Concentration in Doped Diamond Films
Authors: Demlow S.N. , Grotjohn T.A. , Hogan T. , Becker M. , Asmussen J.
Published: April 2011

The electrical characteristics of high quality single crystal boron-doped diamond are studied. Samples are synthesized in a high power-density microwave plasma-assisted chemical vapor deposition (CVD) reactor at a pressure of 160 Torr. The boron-doped diamond films are grown using diborane in the feedgas at concentrations of 0-0.25 ppm, and are compared to those grown previously with 1-10 ppm. The boron acceptor concentration is investigated using infrared absorption, and compared to the boron concentration obtained by SIMS. A four point probe is used to study the conductivity. The temperature dependent conductivity is analyzed to determine the boron dopant activation energy.
Homoepitaxial growth of high quality thick diamond film with microwave plasma CVD technique
Authors: Wang Hong-Xing , Ishigaki Noritaka , Ohkawa Toshiki , Kokami Shinichi , Inoue Hideo , Terajima Ryuuichi , Mutoh Katsuhiko , Kotaki Toshiro
Published: April 2011

A growth of high quality thick diamond film has been carried out on high pressure and high temperature diamond substrate by microwave plasma chemical vapor deposition system. First, the effect of growth parameters on the growth film morphologies was investigated, indicating that the diamond film is very sensitive to the growth temperature and input microwave power. Then, sample holders with different geometries were used in our experiment, illustrating that high quality diamond film can be grown by using the sample holder with flat surface. Finally, the characterization of the as grown samples has been carried out.
The Effect of Silanisation on Microstructural Stability and Magnetic Properties of the Intermetallic Sm2(Co, Fe, Cu, Zr)17·
Authors: Qadeer M. I. , Azdhar Bruska , Savage S. J.
Published: April 2011

The effects of silanising using the coupling agent γ-glycidoxpropyltrimethoxysilane on microstructural stability and magnetic properties of Sm-Co powder particles have been investigated. The silanisation provides structural stability by improving the oxidation resistance at 400oC for 10 hours. The untreated particles undergo microchemical changes by redistribution of alloying elements which mainly accumulate in parallel black and grey streaks in the interior of the particles. The silanised particles after heat treatment show coercivity of 836 Oe and the untreated particles show a much lower coercivity of 376 Oe. The difference in magnetic properties of uncoated particles is caused by diffusion of oxygen and microstructural instability.
Fabrication and Characterization of Single-crystal CVD Diamond Current Amplifier
Authors: Yater Joan E. , Shaw Jonathan L. , Jensen Kevin L. , Feygelson Tatyana , Myers Robert E. , Pate Bradford B. , Butler James E.
Published: April 2011

High-current-density cathodes are required for the development of high-power mm-wave and upper mm-wave devices, as well as for other electron beam applications. To address this need, a current amplifier stage is being developed that will multiply a primary electron-beam current (via the secondary-electron multiplication process) and then emit the amplified beam so as to achieve a current gain of 50-100. Diamond is a particularly promising current amplification source due to the negative electron affinity present at stable hydrogenated surfaces. As such, we are fabricating current amplifiers using single-crystal CVD diamond grown at NRL, with our growth effort focused on reducing the impurity concentration in the epitaxial diamond and on fabricating microns-thick freestanding films. The current amplification characteristics of the diamond films are examined using secondary-electron-emission measurements in both reflection and transmission configurations. In our initial study of an 8.3-µm-thick CVD diamond film, the single-crystal diamond is shown to have superior transport and emission properties compared to similar polycrystalline material. While transmission gains have been obtained under field-free conditions from the unbiased diamond film, we are striving to increase the gain by increasing the transport efficiency in a biased amplifier structure. Towards this end, recent efforts have focused on optimizing the bonding and metallization processes as needed to establish and control the internal electric field. In addition, Monte Carlo simulations are being used to predict the optimal material and device parameters needed to achieve high amplifier gain and low energy spread.
Investigations of microwave and THz radiation losses in CVD diamond and chemically modified diamond
Authors: Scherer T. A. , Strauss D. , Meier A. , Mathis Y.-L. , Judin V. , Müller-Sebert W. , Smirnov W. , Nebel C.
Published: April 2011

To counteract plasma instabilities like Neoclassical Tearing Modes (NTM-modes) in nuclear fusion reactors (JET, ITER, DEMO) high power microwaves are used for the Electron Cyclotron Resonance Heating (ECRH) and for the plasma current drive (CD). The foreseen power level for ITER (Cadarache, France) is Ptot = 24 MW at f = 170 GHz. Each transmission line is designed for a maximum of 2 MW power. The vacuum and tritium barrier to the ITER vacuum vessel is realized by a CVD diamond disk window assembly. Diamond has an extremely high thermal conductivity of about k = 2100 W/Km and a very low loss tangent of tan δ < 10-5 for this frequency and shows therefore a very small microwave absorption. The normalized absorbed power A=Pabs/P0 can be calculated as A = (f/c) • π • (1+εr‘) • tan δ • t (with the rule of thumb estimate: (f/c)=0.5 mm-1; π • (1+εr‘) = 20; tan δ =10-5; A=10-4 • t [mm]); i.e. each t = 1 mm thickness of diamond absorbs Pabs = 100 W of Po = 1 MW microwave power transmitted through the CVD diamond window with an effective tanδ of 10-5.
Influence of methane concentration on the electric transport properties in heavily boron-doped nanocrystalline CVD diamond films
Authors: Janssens Stoffel D. , Pobedinskas Paulius , Petráková Vladimíra , Nesládek Miloš , Haenen Ken , Wagner Patrick
Published: April 2011

A study is presented on the morphology and electric properties of heavily boron-doped nanocrystalline diamond (B:NCD) thin films (≈150snm) grown with two different C/H-ratios (1% and 5%) and a fixed 5000sppm B/C-ratio in gas phase on fused silica substrates. AFM measurements confirm that a higher C/H-ratio leads to smaller grains and more grain boundaries. Electric transport measurements reveal a higher resistivity and a lower mobility as function of the C/H-ratio for all temperatures measured. The resistivity of the 1% sample is almost not temperature dependent while the 5% sample is much more temperature dependent. The electric transport properties of the grain boundaries, more present in the 5% sample, can be responsible for the difference in transport properties of both samples. The active boron concentration, calculated from the electric transport measurements, is remarkably higher for the 5% sample which indicates there is more boron incorporation for higher C/H-ratios. Although both samples are disordered metals, the 1% sample with the least grain boundaries tends more to the behavior of a highly doped single crystalline diamond film, which behaves like a real metal when heavily boron-doped.
50nm Gate-Length Hydrogen Terminated Diamond Field Effect Transistors – Characterization and Inspection of Operation.
Authors: Moran David A. J. , MacLaren Donald A. , Porro Samuele , Hill Richard , McLelland Helen , John Phillip , Wilson John
Published: April 2011

Hydrogen terminated diamond field effect transistors (FET) of 50nm gate length have been fabricated, their DC operation characterised and their physical and chemical structure inspected by Transmission Electron Microscopy (TEM) and Electron Energy Loss Spectroscopy (EELS). DC characterisation of devices demonstrated pinch-off of the source-drain current can be maintained by the 50nm gate under low bias conditions. At larger bias, off-state output conductance increases, demonstrating most likely the onset of short-channel effects at this reduced gate length.
Temperature Dependence of Yield Stress and Dislocation Dissociation in L12-Ordered Intermetallic Compounds
Authors: Inui Haruyuki , Okamoto Norihiko L.
Published: April 2011

The temperature dependence of yield stress and the associated dislocation dissociation in L12 intermetallic compounds are investigated in order to check the feasibility of the classification of L12 intermetallic compounds so far reported in terms of the planarity of core structures of partial dislocations with b = 1/2<110> and 1/3<112> on {111} and {001} glide planes. In contrast to what is believed from the reported classification, the motion of APB-coupled dislocations is proved to give rise to the rapid decrease in yield stress at low temperatures for Co3Ti and Co3 (Al,W). The temperature dependence of yield stress at low temperatures is newly interpreted in terms of a thermal component of solid-solution hardening, at least, for these two L12 compounds. We have proposed a new way to describe the yield stress–temperature curves of L12 compounds with three parameters (the athermal and thermal components of solid-solution hardening and the anomalous strengthening component) when the dislocation dissociation scheme is of the APB-type.
A Phase-Field – Finite Element Model for Instabilities in Multilayer Thin Films
Authors: Zaeem Mohsen Asle , Mesarovic Sinisa Dj. , El Kadiri Haitham , Wang Paul T.
Published: April 2011

Cahn-Hilliard type of phase-field (PF) model coupled with elasticity equations is used to study the instabilities in multilayer thin films. The governing equations of the solid state phase transformation include a 4th order partial differential equation representing the evolution of the conserved PF variable (concentration) coupled to 2nd order partial differential equations representing the mechanical equilibrium. A mixed order Galerkin finite element (FE) model is used including C0 interpolation functions for the displacement, and C1 interpolation functions for the concentration. It is shown that quadratic convergence, expected for conforming elements, is achieved from this coupled mixed-order FE model.

Using the PF – FE model, first, we studied the effect of compositional strain on the PF interface thickness and the results of simulations are compared with the analytical solutions of an infinite thin film diffusion couple with a flat interface.

Morphological instabilities in binary multilayer thin films are investigated. The alloys with and without intermediate phase are considered, as well as the cases with stable and metastable intermediate phase. Maps of transformations in multilayer systems are carried out considering the effects of initial thickness of layers, compositional strain, and growth of a stable/unstable intermediate phase on the instability of the multilayer thin films. It is shown that at some cases phase transformation, intermediate phase nucleation and growth, or deformation of layers due to high compositional strain can lead to the coarsening of the layers which can result in different mechanical and materials behaviors of the original designed multilayer.
Nanoindentation Induced Deformation Near Grain Boundaries of Corrosion Resistant Nickel Alloys
Authors: Herbert F. William , Yildiz Bilge , Van Vliet Krystyn J.
Published: April 2011

The damage accumulation behavior of different grain boundary structures in Inconel 690 (Ni-29wt%Cr-9wt%Fe) was investigated in the presence of large, localized plastic strains induced by nanoindentation. Spatially-resolved hardness was measured as a function of lateral distance from ‘random’ high-angle grain boundaries and twin boundaries. The confinement of induced defects between the indenter tip and grain boundaries did not lead to significant differences in measured hardness between high angle and twin boundaries. Critical “pop-in” loads indicating the onset of incipient plasticity were lower within 1μm of grain boundaries, but were statistically equivalent for random and twin boundaries. These results suggest a comparable extent of dislocation mobility and absorption at the different grain boundary types in Inconel 690 under ambient conditions.
Effects of chemical composition on the structural relaxation in ternary Zr-Cu-Al bulk glassy alloys studied by EXAFS and positron annihilation techniques.
Authors: Ishii A , Mineno S , Iwase A , Yokoyama Y , Konno T J. , Hori F
Published: April 2011

Mechanical properties and thermal stability of bulk glassy alloys depend on their chemical composition ratios, although their detailed local structures especially around free volume have not been clarified yet. In order to know the origin of property dependence on alloy composition in Zr-Cu-Al ternary bulk glassy alloys in a view point of atomic scale, positron annihilation lifetime, coincidence Doppler broadening (CDB) and EXAFS (extended X-ray absorption fine structure) measurements have been employed for eutectic Zr50Cu40Al10 and hypoeutectic Zr60Cu30Al10 bulk glassy alloys before and after structural relaxation by annealing below glass transition temperature Tg.

The result of CDB experiment, which represents the electron momentum distribution around free volume, shows that significant atomic reordering around free volume does not take place by the annealing in each alloy. Besides, CDB ratio profiles for each alloy suggest that the fraction of Zr atom around free volume does not match the chemical composition of each alloy system. Change in positron lifetime, which is proportional to the size of free volume, during annealing for hypoeutectic alloy almost remains unchanged.
Use of clays using ursolic acid with anti-inflammatory
activity
Authors: Domínguez-Patiño M.L. , Chávez-Castillo M. , Rodríguez-Martínez A.
Published: April 2011

Today the company seeks alternative natural medicine that are compatible
with the body, which does not produce side effects and hang time are easily
accessible and cost of those who currently have. The concern of researchers
and specialists in the development of new materials is to seek, to
experiment and create products that can be useful and compatible with human
beings so as to obtain a curative effect without a side effect
originates.

The development of pharmacologically active materials has increased in
recent years. People lack access to most drugs and is therefore a need for
more rapid and less expensive than current, which can be applied to cellular
systems in vitro, in order to evaluate the biocompatibility of new
materials. The current study seeks to experiment in a new line of research
that helps health care and have a better quality of life.

The excipients in the drug are auxiliary substances that help the active
ingredient is the one with the therapeutic action, can be formulated in an
effective and pleasant for the patient. It is one or more substances that
are incorporated into the product to facilitate its preparation, maintenance
or administration. We therefore tested clay known as bentonite to serve as a
vehicle for transport of an active substance (ursolic acid) [1] and some
scientific studies have shown that it possesses anti-inflammatory,
antibacterial, antifungal and highly cytotoxic capacity. Both materials were
mixed to generate a new biomaterial that has anti-inflammatory activity.
Evaluation of this model was under the inhibition of edema produced by
13-acetate-12-ortho-tetradecanoylphorbol (TPA) in mouse ear.