bluuebunny/crossref_metadata_2025 huggingface dataset:
Double-wall Carbon Nanotubes Synthesized by the Abnormal Glow Discharge Plasma Method
Authors: Yoshikawa Hiromichi , Hoshi Fumiyuki , Kyotani Mutsumasa , Ishikura Takefumi , Yumura Motoo , Koga Yoshinori
Published: April 2011

Double-wall carbon nanotubes (DWCNTs) and single-wall carbon nanotubes (SWCNTs) have been synthesized by the DC abnormal glow discharge plasma CVD method using methane and hydrogen gas on a Si substrate coated with catalyst. Fe(NO3)2 and Mo(CH3COCHCOCH3)2O2 with Al2O3 support were used as catalysts. The growth temperatures were 1000 − 1400°C and the gas pressures were 9kPa - 13kPa. DC plasma was generated between an array of four W cathodes and a Cu disk anode, and the applied power was 4000–10000W (2.5–4.0A per cathode, 400–800V). Samples were characterized by high-resolution transmission electron microscopy (HRTEM) and micro-Raman spectroscopy using 514.5 nm Ar ion laser excitation. The HRTEM images showed that many carbon nanotubes had a concentric cylindrical graphene layer structure (DWCNTs). We measured the diameters of the carbon nanotubes (CNTs) from HRTEM images. The outer diameter of the DWNT was 1.52–1.64nm and the inner diameter of the DWNT was 0.73–0.81nm.
Fabrication and Nonlinear Optical Characterization of Well-Ordered Nanopillar Arrays
Authors: Kuo Chun-Wen , Wu Shuo-Wen , Chen Peilin
Published: April 2011

Size-controllable nanostructure fabrication has drawn much of research attention lately, because it may allow the tuning of optical, magnetic, catalytic and electric transport properties of materials. To achieve this goal, we need to investigate the size dependent behavior of materials. The most popular method for size-controlled nanostructure fabrication is e-beam lithography. However, e-beam lithography is not an efficient process for large area fabrication. We report here a novel method to produce large area, well-ordered, size-controlled nanopillar arrays. Nanopillar arrays are among the most studied nanostructures because of their potential applications in photonic crystals, data storage, and sensors. To fabricate nanopillar arrays, we have employed both single layer and double layer nanosphere lithography. Nanosphere lithography, which uses the close packed structure formed by monodispersed colloidal particles as template, is known to produce large area, well-ordered nanostructures on substrate surfaces. These nanostructures have been utilized as the masks in the reactive ion etching process. By carefully controlling the gas composition and etching time, various sizes of nanopillar arrays have been produced. To characterize the optical properties of these nanopillar arrays, surface nonlinear spectroscopy has been used to investigate the size dependent response of nanopillar arrays.
A Simple Method of Tip Shape Calibration for Nano-Indentation Test of Thin Films
Authors: Hattori Koichiro , Xu Junhua , Nakano Hidetoshi , Kojima Isao
Published: April 2011

We have evaluated the hardness and elastic properties of thin films by using a simple procedure to calibrate the tip shape effect of the nano-indentation data. For the simplification, a truncated-shape approximation and linear fit are used to estimate the tip-shape and contact stiffness, respectively, substituting for polynomial area-function and power-law fit. The parameters used in the correction were determined by a fused silica and a single crystal silicon (100) surface. Different film/substrate systems are designed in order to assess these fitted parameters used in the correction. The transition behavior observed from the film to the substrate is well coincide with the other film thickness results, where the indentation depth above 50nm.
Simple methods for measuring tensile and shear bond strength and for determining elastic modulus and strength of coating
Authors: Bao Yiwang , Zhou Yanchun
Published: April 2011

Two new testing techniques, one is for evaluating the ceramics-ceramics and metal-ceramics bond strength, and one is for determining the elastic modulus and fracture strength of brittle coating, were developed respectively. Tensile and shear bond strength were obtained by using compression load on a cross-bonded samples. Rectangular section specimens with surrounding coating or single face coating were used for evaluating the mechanical properties of brittle coating. Analytical formula for the modulus calculation of coatings was derived based on the mechanics of materials. Stress analysis of coated beam provides the expression of the critical stress to fracture in the coating layer. Experimental results confirmed the reliability and convenience of this simple technique.
Mapping of Surface Residual Stress Field by Laser Interferometry Using Stress Relaxation Method
Authors: Kim Dong-Won , Lee Nak-Kyu , Na Kyung-Hoan , Kwon Dongil
Published: April 2011

Based on the identification of the residual stress-free state using electronic speckle pattern interferometry (ESPI), we modeled the relaxed stress in annealing, the thermal strain/stress and the residual stress field in case of both single and film/substrate systems by using the thermo-elastic theory and the relationship between relaxed stresses and displacements. Thus we mapped the surface residual stress fields on the indented bulk Cu and the 0.5μm Au film by ESPI. In indented Cu, the normal and shear residual stress are distributed over -800 MPa to 700 MPa and -600 MPa to 600 MPa respectively around the indented point and in deposited Au film on Si wafer, the tensile residual stress is uniformly distributed on the Au film from 500 MPa to 800 MPa. Also we measured the residual stress by the x-ray diffractometer (XRD) for the verification of above residual stress results by ESPI.
Correlation of Stress and Phase Evolution in Thin Ta Films On Si (100) During Thermal Testing
Authors: French B. L. , Bilello J. C.
Published: April 2011

In this study the stress and morphology of Ta coatings sputtered on Si (100) substrates were monitored in situ and in real-time during thermal testing to allow interruptions at critical events in the coatings' stress evolution. These observations were carried out using white beam Laue transmission diffraction topography/radiography and a high-temperature sample stage at the Stanford Synchrotron Radiation Laboratory (SSRL). The structure of specimens from interrupted thermal tests was then analyzed using x-ray diffraction θ-2θ scans. The structure and phases present in the film at different stages of the thermal test were correlated with specific mechanical responses in the coating such as stress generation. This information was employed to elucidate the role of phase evolution in the respective stress responses of films deposited in high and low-pressure regimes.
Surface and Interface Characterization of Ion Beam Re-crystallized Si
Authors: Sahoo P. K. , Satpati B. , Dey S. , Satyam P. V. , Som T. , Kulkarni V. N.
Published: April 2011

In the present work we have studied efficacy of ion beam induced epitaxial crystallization (IBIEC) to recover amorphous layers (300 – 350 nm) produced by MeV Kr ions in Si(100) and studied the associated changes occurring on surface and interface of the recrystallized region. IBIEC experiments were carried out at sample temperatures in the range of 200 − 400°C using 1 MeV N+ ion beam. Rutherford backscattering-Channeling technique showed planar and gradual recovery of the amorphous layer as a function of temperature. Transmission electron microscopy measurements show good crystalline structure of the recovered region at 400°C while at lower temperatures nano-crystalline Si formation embedded in the amorphous structure is evident. The surface topography studied by atomic force microscopy shows development of islands after IBIEC. The rms roughness is around 0.5 nm and average height of the islands is found to be 1.8 nm. The observed epitaxial growth and the surface topographical features have been correlated.
Multispinneret Methodologies for High Throughput Electrospun Nanofiber
Authors: Bowman Jeremy , Taylor Malcolm , Sharma Vikram , Lynch Anne , Chadha Suneet
Published: April 2011

The overall objective of the Electrospinning program at Foster-Miller is to develop a semi-automated, pilot scale machinery capable of producing nanofiber membranes at reasonable scales so that they can be evaluated for a wide range of military and commercial applications. This paper discusses the development of a high throughput electrospinning process
Anisotropic Hydrogen Permeation in Nano/Poly Crystalline-Nickel Membranes
Authors: Cao Y. , Li H. , Szpunar J. A. , Shmayda W. T.
Published: April 2011

Bilayer nickel membranes have been prepared using electrodeposition to grow polycrystalline nickel on a nanocrystalline nickel substrate. When hydrogen is charged from the nano-Ni side of the nano-Ni and poly-Ni composite membrane, the permeation current increases rapidly, then the membrane releases hydrogen faster during decay. When hydrogen is charged from the poly-Ni side of the same composite membrane, the permeation current rises gradually and takes a longer time to reach steady state. Also the permeability of nano-poly-Ni membrane is eight times higher than that of poly-nano-Ni membrane. The diffusivity for the nano-Ni side charging in a nano-poly-Ni membrane is two times higher than that of poly-Ni side charging of the same membrane. The diffusivity and permeability of nano-poly-Ni membranes are smaller than those for nano-Ni membranes, but larger than those for poly-Ni membranes. Using this anisotropic behavior, one can manipulate hydrogen permeation through composite membranes. A hydrogen permeation model for bilayer membranes is proposed to simulate diffusion in a nano-Ni and poly-Ni bilayer membrane in two-directions of charging. The experimental data is in good qualitative agreement with the model.
Effects of Bleach Reprocessing on Hemodialysis Membranes
Authors: Wolff Susanne H. , Zydney Andrew L.
Published: April 2011

Hemodialysis membranes are exposed to bleach during standard reprocessing methods, but there is little quantitative understanding of the effects of bleach on the mass transfer characteristics or surface properties of these membranes. A battery of experiments was used to evaluate the effects of bleach on the properties of Fresenius F80A, F80B, and Optiflux 180A dialyzers. Bleach caused a significant increase in the membrane hydraulic permeability. The clearance of urea (MW=60 Da) increased by only 3% after a 1-hour exposure to bleach at 50 °C compared to more than a 10-fold increase in the clearance of a 15 kD MW dextran. The solute clearance data were used to determine the effective membrane pore size using available hydrodynamic models. Bleach caused a significant increase in the effective pore size, which was attributed to the leaching of the polyvinylpyrrolidone (PVP) out of the polysulfone membrane. Bleach also caused a significant increase in the magnitude of the negative charge on the membrane surface; the zeta potential varied from −4.1 mV for the new membrane to −13.0 mV after a 14-hour exposure to bleach. These changes in pore size and surface properties provide important insights into the effects of bleach on hemodialysis membranes.
Fabrication of MEMS Devices with Macroporous Silicon Membrane Embedded with Modulated 3D Structures for Optimal Cell Sorting
Authors: Tokranova Natalya , Feng Xiaojun , Olson Steve , Tang Tang , Xu Bai , Castracane James
Published: April 2011

Macroporous silicon is a type of porous silicon that has ordered arrays of channels with high aspect ratio. Macroporous silicon with ordered 3-D structures have a variety of applications such as filters for a particle separation, photonic crystals and optical shortpass filters because of their spatially periodic structures [1–3]. These structures can be prepared by the electrochemical etching (ECE) of silicon wafers in hydrofluoric acid (HF). We report here a way to fabricate macroporous silicon membranes with ordered 3D structures that have controlled periodicity and dimensions appropriate for cell sorting. The silicon 3D structures have pores with variable diameters to modulate the flow behavior and optimize cell sorting efficiency. The silicon membranes were fabricated by wet etching of n-type (100) silicon substrate (40–60 W cm) in potassium hydroxide (KOH) solution with isopropyl alcohol at 80 °C. The 3-D structures were prepared by the electrochemical etching (ECE) of the membranes in diluted HF using the backside illumination with modulated intensity. The thickness of the fabricated membrane has been varied from 20 to 200 mm to optimize filtration of the cells by MEMS (Micro-ElectroMechanical Systems) chips designed for biological cell sorting and cell positioning. The software packages IntelliSuite and ANSYS FLOWTRAN were used to study the mechanical strength of the membrane as well as the velocity profile and flow behavior of Newtonian fluids inside the macroporous silicon membrane.
Aromatics Enrichment in Refinery Streams using Solvent Resistant Membranes
Authors: White Lloyd S. , Wildemuth Craig R.
Published: April 2011

Permselective separation of aromatic from non-aromatic hydrocarbons in feed streams can be accomplished by using membrane systems in hyperfiltration mode. In petrochemical or refinery operations, feed streams containing aromatics such as benzene, toluene, or xylenes can be selectively enriched or depleted in aromatics content. The development program for the STARMEM™ series of membranes led to a commercial process for their large-scale manufacture. A range of membranes in terms of flux and selectivity has been made, and both 2-inch and commercial scale 8-inch diameter spiral wound elements manufactured from these membranes. Tests at 800 psi (55 bar) and 50 °C with a toluene recycle stream have shown stable operation of these modules in hot hydrocarbons. The high efficiencies of these modules allow for high stage cuts (50% and greater) from process streams of thousands of barrels per day. By combining existing refinery operations such as distillation with these new membrane units, cost savings through better purity, recovery, or through-put can be achieved. With these membranes acting as tight hyperfiltration devices, the permeation properties can be modeled through a solution-diffusion equation for molecular transport. Since these membranes also act as solvent resistant nanofiltration devices, unusual benefits can be found while practicing aromatics enrichment of refinery streams, including fractionation of different molecular weight species.
The Preparation of Partially Oriented Zeolite Thin Films via Pulsed Laser Ablation
Authors: Deng Zhongsheng , Pisklak Thomas J. , Balkus Kenneth J.
Published: April 2011

Thin films of zeolites including silicalite-1, mordenite and UTD-18 have been prepared on stainless steel foil via pulsed laser deposition (PLD). Laser ablation of as-synthesized zeolite targets onto stainless steel foil followed by a post hydrothermal treatment results in partially oriented zeolite thin films. SEM, XRD were used to characterize the zeolite thin films. Preliminary results for multilayercoatings of different zeolites will also be presented.
Hydrophilic, heat stable, low protein binding surface modification of PVDF membranes
Authors: Charkoudian John , Xenopoulos Alex , Lynch John
Published: April 2011

Protein binding studies reveal increased levels of protein adsorbed to thermally treated poly-acrylamide-modified PVDF microporous membranes in comparison to polyacrylate-modified membranes. Application of XPS, ToF-SIMS, densitometry and μthermal AFM indicate poly-acryamide-PVDF mixing as the primary cause of the increased protein binding.
Preferential Oxygen Transport in Nanophase Mesoporous Ceramic Ion Conducting Membranes
Authors: Guizard C. , Levy C. , Dalmazio L. , Julbe A.
Published: April 2011

Recent data from the literature dealing with the influence on oxygen transport of porous nanophase ion conducting ceramics are reviewed, and then transposed to the design of mesoporous nanophase ceria-based membranes. Mesoporous CeO2/Al2O3 and Gd doped CeO2 membranes containing Pd and Pt nanoparticles were prepared using the sol-gel process. Permeation of N2 and O2 single gases was studied in a temperature range 20–500°C. Permeation measurements indicate an activated oxygen transport in agreement with the literature data. A synergetic effect of the noble metal nanoparticles on oxygen transport has been evidenced, in relation with the triple phase boundary concept. However, these membranes do not perform totally the preferential oxygen transport predicted by the theory. Several directions are proposed for membrane improvement, in particular concerning pore and grain optimal sizes.
Kinetic Path to Fluid Dynamics in Membranes
Authors: ten Bosch A.
Published: April 2011

Atomic scale dynamic theories and numerical simulation can explore atomistic processes but the relevant physics must fold atomistic understanding into a mesoscopic formulation in terms of average system properties. Transport equations for the density(or concentration), the flux and the pressure tensor are derived from a microscopic basis which mimics simulation by molecular dynamics. The validity of classical hydrodynamics is explored. The method includes interparticle interactions and small scale variations in time and space of relevance to modeling of membrane processes.
Observation of Deformation Substructure in Fatigued Intermetallic Alloys Using Magnetic Properties
Authors: Umakoshi Yukichi , Yasuda Hiroyuki Y.
Published: April 2011

Magnetic properties in ferromagnetic materials are very sensitive to lattice defects such as dislocations and planar faults. Dislocation substructures and planar faults in fatigued intermetallic compounds of Ni3Fe, Fe3Al and FeAl were observed using change in magnetic properties of spontaneous magnetization and high-field susceptibility. This magnetic technique was applied for the nondestructive evaluation of fatigue life.
Effects of Solidification Parameters on Lamellar Microstructures of Near Eutectic Cr-Cr3Si Alloys
Authors: Bei H. , George E. P. , Pharr G. M.
Published: April 2011

Directional solidification of Cr-Cr3Si eutectic alloys has been carried out using a high temperature optical floating zone furnace. Uniform and well-aligned lamellar structures were obtained over a fairly wide range of intermediate growth rates but not at very low or very high growth rates where degenerate and cellular structures, respectively, were obtained. The lamellar spacing was found to increase with decreasing solidification rate, in agreement with the Jackson-Hunt theory. In addition, for a fixed growth rate, the lamellar spacing was found to increase with increasing rotation rate. Lamellar structures could also be produced at off-eutectic compositions, but only for a limited range of growth conditions. The Cr-rich lamellae are effective in stopping indention cracks nucleated in the brittle Cr3Si phase.
High Temperature Resistant Intermetallic Nial-Based Alloys with Refractory Metals Cr, Mo, Re - Structures - Properties - Applications -
Authors: Frommeyer G. , Rablbauer R.
Published: April 2011

The stoichiometric intermetallic compound NiAl with B2 superlattice structure exhibits superior physical and high-temperature mechanical properties, and excellent oxidation resistance. The main disadvantages of polycrystalline NiAl are the lack in plasticity and fracture toughness below the brittle-to-ductile-transition temperature of about 550°C. Insufficient high-temperature strength and creep resistance occur at temperatures above 800°C. Despite these facts NiAl-based alloys are still considered as promising structural materials for high-temperature applications. The refractory metals Cr, Mo, and Re with b.c.c. and h.c.p. lattice structures form with NiAl quasi-binary eutectic systems, showing high melting temperatures and thermally stable microstructures. Elasticity, solid solution hardening, fibre reinforcement, and creep properties were investigated in view of the constitutional defect structure and microstructural features. Especially the fibre reinforced NiAl matrix composites possess optimum high-temperature strength up to 1200 °C, and improved creep resistance as well.
Observation of structural modulations and formation of H-carbides and ζ-silicides during α2 → γ transformation in fully lamellar γ-TiAl
Authors: Karadge M. , Gouma P. I.
Published: April 2011

The present paper illustrates the experimentally observed microstructures related to α2 → γ + Ti2AlC (H-carbide) and Ti5Si3 (ζ silicide) phase transformations in fully lamellar Ti-46Al-2Cr-3Nb-0.2W-0.2Si-0.1C alloy. These transformations were observed by in-situ heat treatments in the TEM at temperatures up to 800°C and by post heat treatment examination in a high-resolution transmission electron microscope. α2 dissolution was observed to start both inside the lath and at the α2/γ interface. H-type carbides were observed to nucleate inside the α2 lath, which explains the appearance of long arrays of well-aligned structures along prior α2 laths in creep-deformed samples. ζ silicide precipitates nucleate at the α2/γ interface, this growth occurs epitaxially along the pre-existing <0001>α2 direction. Modulated structures were observed during the α2 → H, newly formed γ and at the α2 / ζ interface. All these modulated structures consist of regular arrangement of stacking faults and dislocations.
Precipitation Phenomena and Strain Hardening of Intermetallic Titanium Aluminides
Authors: Müllauer J. , Appel F.
Published: April 2011

In two-phase titanium aluminide alloys, the implementation of precipitation reactions is a widely utilized concept to control the microstructure and strengthen the material. A study has been made on the influence of carbide and boride precipitates on dislocation mobility and strengthening at 300 K. Compression tests were carried out for characterizing the mechanisms determining flow stress and dislocation glide resistance. The interaction mechanisms between the precipitates and dislocations were assessed by thermodynamic glide parameters and transmission electron microscopy. It has been shown that small titanium boride precipitates and carbide precipitates of perovskite type act as long-range dislocation glide obstacles. The interaction between the dislocations and the borides and carbides mainly leads to an athermal stress contribution. However, the dislocation-particle interactions are quite different. Small groups of borides are encircled by dislocations. This gives rise to the formation of loop structures the density of which increases with strain. On the contrary, the carbide precipitates are shearable and can be overcome without Orowan looping. This different behaviour is also reflected in the work hardening characteristics. Whereas the work hardening coefficient of the boron doped material increases with increasing B-concentration, it is independent of concentration in the case of the carbon-doped material.
Microstructure and Oxidation of a Cast Nickel Aluminide Alloy
Authors: Lee D. Y. , Santella M. L. , Anderson I. M. , Pharr G. M.
Published: April 2011

Specimens of the cast Ni3Al alloy IC221M were annealed in air at 900°C to examine the effects of oxidation and thermal aging on the microstructure. The alloy is comprised of a dendritically solidified γ-γ′ matrix containing γ+Ni5Zr eutectic colonies in the interdendritic regions. Microstructures of aged specimens were examined by optical microscopy and energy dispersive X-ray (EDX) spectrum imaging in the scanning electron microscope (SEM). Two primary changes in the microstructures were observed: (1) there is considerable homogenization of the cast microstructures with aging, and (2) the volume fraction of the γ+Ni5Zr eutectic decreases. Oxidation products were identified using x-ray diffraction and EDX spectrum imaging with multivariate statistical analysis (MSA). During the initial stages of oxidation, the first surface oxide to form is mostly NiO with small amounts of Cr2O3, ZrO2, NiCr2O4, and θ-Al2O3. Initially, oxidation occurs primarily in the interdendritic regions due to microsegregation of alloying elements during casting. With further aging, a continuous film of α-Al2O3forms immediately beneath the surface that eventually evolves into a double layer of α-Al2O3and NiAl2O4. Although these oxides are constrained to the near surface region, others penetrate to greater depths facilitated by oxidation of the γ+Ni5Zr eutectic colonies. These oxides appear in the microstructure as long, thin spikes of ZrO2surrounded by a thin sheath of Al2O3.
Microstructures and Tensile Properties of Cold-rolled Thin Foils of Binary Ni-Al γ/γ' Alloys
Authors: Li Dingqiang , Demura Masahiko , Kishida Kyosuke , Suga Yozo , Hirano Toshiyuki
Published: April 2011

Three single crystal plates of γ/γ' Ni-Al two-phase alloys with near cube, Goss and intermediate orientations between cube and Goss were cold-rolled to 300 μm-thick foils with 83% reduction. Tensile tests of the foils were performed at room temperature to study the effect of rolling microstructures and textures on the mechanical properties. The fracture strength of all the foils was very high, 1.4–1.7 GPa, having a small initial normal direction (ND) dependence and a small difference between rolling direction (RD) and transverse direction (TD). The foils fabricated from initial cube and intermediate orientations showed necking and a small fracture elongation when tensile-tested along RD, while the foil fabricated from initial Goss orientation did not show necking and fracture elongation. All the foils showed small fracture elongations due to shear band formation when tensile-tested along TD.
The Effects of Substitutional Additions on Creep Behavior of Tetragonal and Hexagonal Nb-Silicides
Authors: Bewlay B. P. , Briant C. L. , Sylven E. T. , Jackson M. R.
Published: April 2011

Nb-silicide based in-situ composites combine a ductile Nb-based solid solution with high-strength silicides, and they show great promise for aircraft engine applications. The Nb-silicide controls the high-temperature creep behavior of the composite. Previous work has shown that the silicide composition has an important effect on the creep rate, with particular attention on the role of Ti and Hf additions. The aim of the present study is to understand the effects of the substitutional elements on the stability of the silicide phase, ordering in the crystal lattice, including the hP16-tI32 transition, and the creep behavior of the monolithic phases. To pursue this goal monolithic alloys with a range of compositions were prepared and the creep rates were measured at temperatures of 1100–1350°C. The stress sensitivities of the creep rates of the monolithic phases were also determined.
Fe tracer diffusion in L10 ordered FePt
Authors: Nosé Y. , Ikeda T. , Nakajima H. , Tanaka K. , Numakura H.
Published: April 2011

Tracer diffusion coefficient of 59Fe in FePt with the tetragonal L10 ordered structure has been measured by an ion-beam sputter-sectioning technique in the temperature range from 1173 to 1374 K. Anisotropy in diffusion has been studied using single-variant single-crystal specimens. The diffusion coefficient in the direction perpendicular to [001] axis (in the a-axis direction), Da, is larger than that in the [001] (c-axis) direction, Dc, as expected from the atomic arrangement of the L10 ordered structure. The ratio of the diffusion coefficients, Da/Dc, is 1.33.6 for Fe42Pt58 and smaller at higher temperatures. The activation energy for the diffusion is 259 ± 1 kJ/mol for Da and 309 ± 18 kJ/mol for Dc, while the pre-exponential factor is and , respectively in Fe42Pt58.
Defect Structures of Intermetallic FeRh Alloys Induced by High-Speed Deformation
Authors: Kibata Yasunori , Hori Fuminobu , Oshima Ryuichiro , Komatsu Masao , Kiritani Michio
Published: April 2011

In order to study the role of vacancy-type defects in the unique deformati on-induced phase transition mechanisms of B2-L10 and B2-A1 of intermetallic compound Fe-Rh alloys, high-speed impact compression deformation has been carried out. Induced phases and substructures were examined by XRD and TEM. The relation between the phase transitions and vacancy-type defects was investigated by the positron annihilation Coincidence Doppler Broadening (CDB) method. The results showed that intermixed phases of L10 and A1 were always formed in the B2 phase, and the vacancy concentrations were rather decreased in the specimens deformed by higher strain rates, suggesting that vacancies were more consumed by the phase transition to A1 structure.
The Effects of Ternary Elemental Additions on the Structure and Magnetic Properties of Nanocrystalline Feco Powders
Authors: Baker I. , Quiller R. G. , Robson M. , Wu D.
Published: April 2011

Powders of near-equiatomic Fe and Co were mechanically milled with additions of Zr, C, Ni, Cu and/or B for 60 hr using stainless steel balls in a Svegari attritor operated at 1300 r.p.m. under argon. The milled powders were examined before and after annealing at 600 °C. The morphologies and sizes of the powders were examined using a scanning electron microscope. The grain sizes were characterized from the widths of X-ray diffraction peaks obtained using a computer-controlled x-ray diffractometer and the lattice parameters were determined. The resulting magnetic properties were measured using a vibrating sample magnetometer.
Phase Transformation of Ti-Ni Containing Platinum-Group Metals
Authors: Hosoda Hideki , Tsuji Masahiro , Mimura Motoki , Takahashi Yohei , Wakashima Kenji , Yamabe-Mitarai Yoko
Published: April 2011

Since the maximum shape recovery temperature of the binary Ti-Ni alloys is limited to be around 400K, the increase in martensitic transformation temperature (Ms) of Ti-Ni should be done by alloying for the demand of high temperature applications. Although most of additional elements are known to decrease Ms of Ti-Ni, substitutional elements having large atomic size are expected to increase Ms. In this study, phase constitution, phase transformation temperature, lattice parameter of B2 phase and Vickers hardness were investigated for Ti-Ni alloys containing several platinum-group metals (PGM). The alloy systems investigated were the pseudobinary systems of TiNi-TiRh, TiNi-TiIr and TiNi-TiPt where the PGM atoms substitute for the Ni-sites of TiNi. The phase transformation and phase constitution were assessed by differential scanning calorimetry (DSC), X-ray diffraction analysis (XRD) and transmission electron microscopy (TEM). It was found by XRD that TiNi can contain a large amount of the PGMs as Ti(Ni, Rh), Ti(Ni, Ir) and Ti(Ni, Pt). Lattice parameters monotonously increase with increasing amount of PGMs. With increasing Pt content, Ms slightly decreases when less than 10mol%Pt while continuously increases as the rate of 26K/mol%Pt when more than 10mol%Pt. On the other hand, Ms decreases and then disappears with increasing Rh or Ir content. Hardness ranges from HV180 to HV570 and the maximum values in the pseudobinary systems lie around 20–30mol%PGM, suggesting solid solution hardening caused by the substitution of PGMs.
Reversible Hydrogen Absorption/Desorption and Related Lattice Deformation of Ti3Al Based Alloys in the Ti-Al-Nb System
Authors: Ito Kazuhiro , Zhang Lanting T. , Okabe Yoshiharu , Vasudevan Vijay K. , Yamaguchi Masaharu
Published: April 2011

Hydrogen absorption/desorption of Ti3Al-based alloys with α2 single-phase, β0 single-phase and β/O two-phase microstructures was investigated to obtain systematic understanding microstructure effects. On exposing all the alloys to hydrogen, β (βH) and γ (γH) hydrides are formed. The βH and γH have bcc and bct (close to fcc) based structures, respectively. The hydrogen/metal ratio of the γH is larger than that of βH. Thus, solute hydrogen in Ti3Al based alloys stabilizes the bcc-based phase just like Nb, regardless of their original structure before hydrogenation. On the other hand, reversible hydrogen absorption/desorption around 100°C and related reversible βH-γH transformation was observed in β/O two-phase (Ti,Nb)3Al and α2-Ti3Al alloys, but not obviously observed in a β0-(Ti,Nb)3Al alloy. In forming the βH, the expansion of the β0 and β phases occurred isotropically keeping their structures B2 and bcc, respectively. In contrast, the O and α2 phases expanded in anisotropic manner. The lattice deformation for the βH→γH transformation can be described similarly to those for the O→βH and α2→βH transformations. Such lattice deformation in anisotropic manner most likely agrees with that observed in a martensitic displacive transformation, because of the surface relief observed on the γH after the βH→γH transformation in the β0-(Ti,Nb)3Al alloy and many twins formed during the α2→βH transformation in the α2-Ti3Al alloy. Mechanisms of the reversible βH-γH transformation in the β/O two-phase (Ti,Nb)3Al and α2-Ti3Al alloys was proposed on the basis of similarities in the lattice deformation and ordering of hydrogen atoms required for the βH-γH, O-βH and α2-βH transformations.
Plastic Deformation Behavior of Al5Ti3 Single-Phase Single Crystals
Authors: Nakano Takayoshi , Hayashi Koutaro , Nagasawa Yosuke , Umakoshi Yukichi
Published: April 2011

Al5Ti3 single-phase single crystals with the stoichiometric composition of Ti-62.5at.%Al were obtained by the floating zone method and subsequent heat treatment at 750°C for 48h. The crystals contain no L10 phase, but compose of anti-phase domains (APD) surrounded by the anti-phase boundary (APB) on the basis of the Al5Ti3 long-period superstructure.

Orientation dependence of plastic deformation behavior and operative slip system were examined in compression in a wide temperature range between RT and 750°C using the single-phase single crystals in comparison with Al-rich TiAl single crystals with the L10 matrix and Al5Ti3 precipitates. In the wide crystal orientation area, {111)<110] ordinary slip appeared independent of the tested temperature, while {111)<101] superlattice slip was operative only at around [001] and [110] axes. This is because the critical resolved shear stress (CRSS) for the ordinary slip is lower than that for the superlattice slip and that for the ordinary slip in other Al-rich TiAl crystals containing L10. This implies that existence of the L10 matrix with the Al5Ti3 phase must be closely related to strengthening for the ordinary slip, similarity in Ni-base super-alloys consisting of the Ni-based matrix and L12 precipitates. The CRSS for both slips gradually decreased or was kept constant with temperature, showing no remarkable anomalous strengthening.

In this paper, deformation mechanism in Al5Ti3 single-phase single crystals will be discussed focusing on condition of the Al5Ti3 superstructure.
Formation and Characterisation of Periodically Structured B2-Aluminides Thin Films by Laser Interference Irradiation
Authors: Liu K. W. , Mücklich F.
Published: April 2011

B2-aluminide thin films can be used as protective layers to prevent mechanical, thermal and chemical impact on the main components and as intermediate thermal or diffusion barrier layers for semiconductor contacts. Laser irradiation can induce phase transformation due to thermal interaction with sample surface. Moreover, with laser interference, the laser power can be distributed periodically on interference points or lines. The scale of the pattern, sub-micrometer to dozens of micrometer, can be varied easily to the typical scale of grain sizes. In this work, B2-structured NiAl and RuAl thin films with periodic pattern are prepared from corresponding elemental bi-films by laser interference irradiation. The micro-nano-structured surface constitutes of a line-like pattern with a period of about 5 micrometer. There occur melting and re-solidification processes during laser interaction with sample surface. The line-like patterns possess fine grains with a size of about 20 nm in Ni/Al and 5 nm in Ru/Al bi-films. The appearance of B2-structured NiAl and RuAl phases are confirmed by TEM. It is proposed that the phase transformation from initial metastable solid solution to the B2 phases can be induced by laser irradiation.
Amorphization of C15 Laves RFe2 compounds by hydrogen absorption
Authors: Aoki K. , Dilixiati M. , Ishikawa K.
Published: April 2011

C15 Laves RFe2 (R= Y, Ce, Sm, Gd, Tb, Dy, Ho and Er) compounds were thermally analyzed to elucidate conditions of hydrogen-induced amorphization (HIA), i.e. amorphization of intermetallics by hydrogen absorption, using a pressure scanning differential calorimeter (PDSC) in a hydrogen atmosphere of 1.0 MPa. As the temperature increases, hydrogen absorption in the crystalline state, HIA, precipitation of RH2 in the amorphous phase and decomposition of the remaining amorphous phase into RH2+oc-Fe occur exothermally for RFe2 (R=Y, Sm, Gd, Tb, Dy and Ho). HIA and precipitation of ErH2 occur simultaneously in ErFe2. On the contrary, hydrogen absorption of CeFe2 always leads to HIA, i.e. no hydrogen absorbed crystalline phase is formed. The mechanism of HIA in the C15 Laves phases RFe2 is discussed on the basis of the experimental results.
A Cr(IV) based 1212-type cuprate
Authors: Ruiz-Bustos Rocío , Aguirre Myriam H. , Alario-Franco M.Á.
Published: April 2011

By means of high pressure and high temperature we have prepared a new material similar to the classic YBa2Cu3O7 (Ybacuo) superconductor but having chromium in the so-called charge reservoir layer: CrSr2YCu2O8. It has been characterised by different techniques such as X-ray diffraction, TEM, ED, EDS, and magnetic susceptibility. The new material is isostructural with the Ru equivalent compound (RuSr2YCu2O8). An antiferromagnetic transition is observed on cooling below 130 K. The as prepared material is not superconducting down to 4 K.
Stabilization of beta-SrAl2O4 with Eu Prepared by Spray Pyrolysis
Authors: Shi W.S. , Yamada H. , Nishikubo K. , Kusaba H. , Xu C.N.
Published: April 2011

The effect of doping europium on the structure of strontium aluminate (SrAl2O4:Eu) synthesized by spray pyrolysis was studied. Results revealed that all of the as-sprayed samples were a mixture structure of monoclinic and hexagonal phases. However, the structural behaviors of the SrAl2O4:Eu post-calcinated at 1300°C in reducing ambient for 2hrs strongly depended on the europium concentrations. As increase of the europium concentrations, a characteristic of hexagonal phase could be observed from the post-annealed samples. Up to 12 percent of strontium were replaced by the europium, the structure of the post-annealed sample achieved a pure hexagonal phase. The mechanism of the phase dependence of the SrAl2O4:Eu on europium concentration was discussed.
Nuclear and Magnetic Structures of K2NiF4-type Iron(III) Oxide Halides
Authors: Hector Andrew L. , MacDonald Alexander I. , Price Daniel J. , Weller Mark T.
Published: April 2011

K2NiF4-type iron(III) oxides show a very common form of magnetic ordering, XY antiferromagnetic ordering within the layers combined with layer stacking based on alignment of spins in alternate layers. The Ising antiferromagnet Ca2MnO4 has been reported to have a doubled c-axis (ca 24Å) in the magnetic structure and we have found a similar stacking in the XY antiferromagnet Sr2FeO3F. We show here that this unusual c-axis doubling is related to the exposure of the material to air and suggest that in both Sr2FeO3F and Ca2MnO4 it may be related to the occupation of interstitial sites.
Synthesis and Characterization of Neutral and Cationic Layered Materials Based on Heavier Group 14 Metals: BING-5, -6, -9, -10
Authors: Tran Dat T. , Zavalij Peter Y. , Oliver Scott R. J.
Published: April 2011

Our research involves the solvothermal synthesis and characterization of new 3D open-framework and low dimensional inorganic materials. We focus on heavier group 14 elements to prepare structures that are analogous to aluminosilicate zeolites, but the main emphasis is to obtain cationic materials, a feat not possible with silicon oxides. We have successfully synthesized a series of novel compounds with Pb as building block: a cationic layered lead fluoride material (BING-5, Pb3F5NO3); a neutral, layered lead phenylphosphonate pyridine (BING-6); and a layered lead metamethylphenyl-phosphonate (BING-9). A molecular solid, tetrafluorodipyridine-germanium (BING-10) was also obtained. These structures are characterized by a variety of solid state techniques, including: powder X-Ray diffraction (PXRD), thermogravimetric analysis (TGA), UV-Vis spectroscopy and NMR. Our BING-5 material can exchange its interlayer NO3- for a variety of other anions. It is also stable to 450°C, which is far superior to organic resins that are still the standard for anion-exchange.
Ferroelectric nanocomposite with high dielectric constants
Authors: Pham Mai T.N. , Boukamp B.A. , Bouwmeester H.J.M. , Blank D.H.A.
Published: April 2011

Composites between ferroelectric material and a dispersed metal phase are of great interest due to the improvement in dielectric properties for such applications as high capacitance capacitors, non-volatile memory, ect. Using a colloidal method, Pt particles with a size of 3–5 nm were dispersed homogeneously in a PZT (PbZr0.53Ti0.43O3) matrix. No unwanted reaction phase between PZT and Pt during sintering at 1150 °C could be detected by X-ray diffraction. Electrical properties were investigated by impedance spectroscopy measurement. The effective dielectric constant increased remarkably as a power function of Pt volume content and can be described by the percolation theory. At 25 vol.% of Pt the dielectric constant of the composite is 4 times larger than that of pure PZT. The temperature dependence of the electrical properties is also influenced by the metallic phase fraction.
Synthesis and Sintering of (K,Na)NbO3 Based Ceramics
Authors: Malic Barbara , Jenko Darja , Bernard Janez , Cilensek Jena , Kosec Marija
Published: April 2011

Stoichiometric K0.5Na0.5NbO3 solid solution(KNN) was prepared by solid-state synthesis from alkaline carbonates and niobium oxide. Thermal decomposition of the powder mixture occurs upon heating to 700 °C followed by crystallization of the perovskite phase. After sintering at 1100 °C, 2h the stoichiometric KNN reaches 94 % of theoretical density. Dielectric constant of stoichiometric KNN is 620, and the losses 0.03.
Contrasting Structural Behavior in the Aurivillius Phase Ferroelectrics Bi4Ti3O12, BaBi4Ti4O15 and Ba2Bi4Ti5O18
Authors: Lightfoot Philip , Snedden Alan , Blake Susan M. , Knight Kevin S.
Published: April 2011

The crystal structures of the Aurivillius phase ferroelectrics Bi4Ti3O12, BaBi4Ti4O15 and Ba2Bi4Ti5O18, containing perovskite-like layers consisting of three, four and five adjacent TiO6 octahedra, respectively, have been analysed using high-resolution powder neutron diffraction data. At 2K the structure of Bi4Ti3O12 can be successfully modelled in the orthorhombic space group B2cb, with no evidence of the monoclinic distortion in the ferroelectric phase suggested by previous single crystal studies. At 298K BaBi4Ti4O15 shows a subtle orthorhombic distortion, but without the octahedral tilting seen in related ferroelectric phases, and is refined in space group F2mm. At 298 K Ba2Bi4Ti5O18 adopts a tetragonal polar phase (I4mm), thus displaying a third type of polar distortion within this family. It is suggested that these differences arise from a ‘tolerance factor’ type mechanism whereby the increasing content of the large Ba2+ cation causes a shift from underbonding at the perovskite A-site to underbonding at the perovskite B-site resulting in a change in the mechanism of ferroelectricity from A-site displacements to B-site displacements, akin to the mechanism in BaTiO3.
Structure, magnetization and Mössbauer study of nanostructured Ni0.5Zn0.5Fe2O4 ferrite powders
Authors: Ge Shihui , Zhang Zongtao , Wu Mingzhong , Zhang Y.D. , Yang D. P. , Budnick J. I. , Hines W. A.
Published: April 2011

Nanostructured ferrites possess more advantages than the conventional ferrite materials and have been a research focus recently. In this work, a series of nanostructured Ni0.5Zn0.5Fe2O4 were synthesized by a citrate reaction method followed by calcining at various temperatures with the goal of obtaining pure phase Ni0.5Zn0.5Fe2O4 nanoparticle while keeping the size small. X-ray diffraction, transmission electron microscopy, SQUID magnetometry and Mössbauer spectroscopy (ME) have been employed to characterize the crystal structure, phase homogeneity, particle size, the conditions for reaction completion, and the magnetic properties. The results show that the saturation magnetization Ms at both 10K and 300K increase with increasing calcination temperature Tca, but particle size also increases with Tca. Three factors, the incomplete reaction for ferrite phase formation, the surface effect and superparamagnetic behavior, are found to be responsible for low Ms values at lower Tca. Based on a detailed analysis of nanostructure and magnetic properties in ferrites, the optimal conditions for synthesizing nanostructured Ni0.5Zn0.5Fe2O4 have been established.
Ag Ion-Exchange Reactions of Cu2P3I2 and Cu2P1.8As1.2I2
Authors: Jayasekera Buddhimathie , Brock Stephanie L.
Published: April 2011

A variety of ion exchange techniques for Cu2P3I2 and its mixed pnictogen analog Cu2P1.8As1.2I2 have been studied. Ag2P3I2 is an existing material, previously prepared from Cu2P3I2 by ion exchange of Ag+ for Cu+ in aqueous medium. This method is compared to non-aqueous (ionic liquid) and solid state routes for ion exchange. Additionally, the new compound Ag2P1.8As1.2I2 with cell parameters a = 15.838(17) Å, b = 13.684(10) Å, c = 15.580(17) Å and β = 117.63(7)°, has been prepared by reaction of Cu2P1.8As1.2I2 with AgNO3 in aqueous solution.
Heterogeneous Design: Concentration Fields Determination with the Unique Crystallization Schemes and Microstructures
Authors: Lutsyk Vasily I. , Vorob'eva Vera P.
Published: April 2011

New approach to calculation of microstructure by means of the one-phase regions borders equations is proposed. Projections of all geometrical elements of phase diagram to the concentration simplex divide it to fields with unique crystallization schemes. All crystallization stages for the given concentration field are simulated and as a result the all elements of microstructure is designed and origin of every phase is shown.
New Method of Preparation of Superionic BaSnF4
Authors: Dénès Georges , Muntasar Abdualhafed , Retrif Tony
Published: April 2011

The first preparation of superionic BaSnF4, BaSnF4(ssr), was carried out in 1975 by direct reaction at high temperature between appropriate amounts of BaF2 and SnF2 under inert conditions in sealed copper tubes. In the present work, BaSnF4(aq2) was synthesized for the first time by the wet method. X-ray powder diffraction and Mössbauer spectroscopy were used to characterize the products, and show that BaSnF4(aq2) and BaSnF4(ssr) are the same material.
Synthesis of Metal-doped Cryptomelane Nanomaterials using Cross-linking Reagents
Authors: Liu Jia , Cai Jun , Shen Xiongfei , Suib Steven L. , Aindow Mark
Published: April 2011

Three cross-linking reagents (PVA, glycerol and glucose) have successfully been used to synthesize non-doped and metal-doped nanosized cryptomelane materials via a solid-state preparation method. The 2×2 tunnel structure of cryptomelane was formed at 500 °C. FT-IR data show that no cross-linking reagent residues were found in the products after the reactions were complete at 800 °C. The metal dopants used were Fe, Ag, Co, Cu, Ni, and Zn. XRD data show that Fe and Co cations can be doped into the materials without the formation of additional phases. The tunnel structures of the nanosized materials exhibit long-range along the b axis, as indicated by transmission electron microscopy data. High-resolution scanning electron microscopy studies show that morphologies of the products are nanorods or nanofibers, depending on the cross-linking reagents used in the preparation. Thermogravimetric analyses indicate that these nanomaterials are thermally stable to 700 °C.