Sudden jumps in nanoindentation load-displacement curves of bulk metallic glasses (BMGs) signify the onset of plastic deformation. These events are investigated on varying compositions of Zr- and Hf-rich BMGs. Load-versus-displacement graphs for spherical indentations are analyzed to determine displacement, load, intensity of deformation, energy per volume, energy loss, and pressure corresponding to these key locations. Attention is focused on pressure, energy loss, and energy per volume at initial plasticity in response to varying strain rates, indenter tip radii, preload, and material composition. Energy loss was found to correlate with preload. The Zr-rich metallic glass was found to plastically deform in response to smaller loads than Hf-rich specimens.

Creation of mirror dots, localized areas of smooth surface with a shape of laser beam on a glass material, using a XeCl laser irradiation is reported. Laser irradiation of a 40BaO–40TiO2–20B2O3 sample heated to 300 °C induced a smooth and flat surface, where no scratches caused by a mechanical polishing were observed. The present finding indicates that the melting of the surface occurred by the combined effect of the heat-assistance and the increased absorption coefficient of TiO2. In the present system, the absorption coefficient in the ultraviolet region, which originates from TiO2, was found to increase with increasing temperature. The presented technique will open new possibilities in integrated optics; the surface of a small protruded or hollow area can be made smooth, which cannot be achieved by conventional mechanical polishing.

We have studied the heteroepitaxial growth of 3C–SiC film on an Si(100) substrate by plasma chemical vapor deposition using monomethylsilane, a single-molecule gas containing both Si and C atoms. We have tried to introduce an interval process, in which we decrease the substrate temperature for a few minutes at a suitable stage of film growth. It was expected that, during the interval process, stabilization such as desorption of nonreacted precursors and lateral diffusion of species produced at the initial stage of film growth would occur. From the results, it appears that the interval process using a substrate temperature of 800 °C effectively suppresses polycrystallization of 3C–SiC growth on the Si(100) surface

Fe-sheathed MgB2 tapes were fabricated using powder chemically treated through an ex situ process employing a powder-in-tube (PIT) technique. The treatment of MgB2 powder in a benzene solution of benzoic acid caused the pulverization and disappearance of large grains. Compared with the pristine powder without treatment, the tape made from this powder showed a fivefold increase in critical current density (Jc) in 10 T. This was due to the pulverization of grains by the chemical treatment and the removal of surface MgO layers from MgB2 grains by dissolution in the acid solution. The removal of MgO layers was effective in promoting substitution of carbon from the solvent for boron.

In this study, bulky titanate nanotubes with dense microstructures were successfully fabricated by a hydrothermal hot-pressing (HHP) technique with water as a reactive solvent. Titanate-based nanotubes of about 10 nm outer diameter and 5 nm inner diameter and a few hundred nanometers in length were synthesized by a hydrothermal treatment of anatase-type TiO2 powder in a 10 M NaOH aqueous solution. From results of N2-adsorption and transmission electron microscopy observation, it was obvious that HHP processed samples were composed of nanotubular structures and that the obtained bulks possessed mesopores and high Brunauer–Emmett–Teller surface area. These results suggested that the obtained bulks possessed functionality as good as that of powders of titanate nanotubes. Thus, the HHP technique may be a useful method for fabricating bulky titanate nanotubes and may be applied in the solidification of the other some nanotubular materials.

A thermal metalorganic atomic layer deposition (ALD) process was developed for the in situ, sequential growth of Pt/TaNx stacks for use as barrier/seed stacks for subsequent copper electroplating. Ultrathin platinum films were deposited by alternating pulses of (methylcyclopentadienyl)trimethylplatinum (MeCpPtMe3) and oxygen (O2) as co-reactants. An ALD process window was established and optimized by investigating saturation of Pt film-growth rate versus MeCpPtMe3 and O2 exposure as controlled by the length of reactant pulses and the duration of the inert gas purge cycles separating the reactant pulses. The resulting low-temperature (300 °C) ALD Pt process yielded uniform and continuous Pt films with typical carbon and oxygen impurity levels around, respectively, 2.5 and 1 at.%. Film conformality was nearly 100% in 120-nm trench structures with 11:1 aspect ratio.

Taking Au as an example, we have investigated the epitaxial bain paths of 〈001〉 oriented face-centered-cubic metal nanowires. It demonstrates that there are one stable and one metastable phase, having the lattice constant ratio c/a of about 0.6 and 1.0, respectively. Even without any external stimuli, the surface-tension-induced intrinsic stress in the interior may drive the nanowires to phase transform spontaneously for surface-energy minimization. However, this structural transition depends on the feature sizes of the nanowires. Specifically, only when the cross-section areas are reduced to 4.147 nm2 or so can the surface energy and the intrinsic stress satisfy the thermodynamic and kinetic conditions simultaneously.

Suspension plasma spraying was used to synthesize Y2O3 nanoparticles. The Y2O3 starting material was first dispersed in a solvent to form a suspension and then injected axially into the plume of an inductive radio frequency plasma. It was found that the as-sprayed Y2O3 particles had a size distribution from nano to micron scale and various morphological features, which varied with processing conditions as well as solvent and plasma gas type. In comparison with water, organic solvents led to a higher productivity and smaller particle size, whereas water introduced impurities such as Y2O2C2, which is isotypic to La2O2C2. Introduction of oxygen as an auxiliary plasma gas was an effective way to eliminate this impurity. In addition, complete combustion of the organic solvent and recombination of oxygen atoms above 4000 K also elevated the heat treatment degree of Y2O3. As a result, application of O2 with an organic solvent resulted in an even smaller mean particle size and narrower size distribution.

Microstructure of sintered nanocrystalline SiC is studied by x-ray line profile analysis and transmission electron microscopy. The lattice defect structure and the crystallite size are determined as a function of pressure between 2 and 5.5 GPa for different sintering temperatures in the range from 1400 to 1800 °C. At a constant sintering temperature, the increase of pressure promotes crystallite growth. At 1800 °C when the pressure reaches 8 GPa, the increase of the crystallite size is impeded. The grain growth during sintering is accompanied by a decrease in the population of planar faults and an increase in the density of dislocations. A critical crystallite size above which dislocations are more abundant than planar defects is suggested.

The factors governing the transport properties of yttrium-doped barium zirconate (BYZ) have been explored, with the aim of attaining reproducible proton conductivity in well-densified samples. It was found that a small initial particle size (50–100 nm) and high-temperature sintering (1600 °C) in the presence of excess barium were essential. By this procedure, BaZr0.8Y0.2O3−δ with 93% to 99% theoretical density and total (bulk plus grain boundary) conductivity of 7.9 × 10−3 S/cm at 600 °C [as measured by alternating current (ac) impedance spectroscopy under humidified nitrogen] could be reliably prepared. Samples sintered in the absence of excess barium displayed yttria-like precipitates and a bulk conductivity that was reduced by more than 2 orders of magnitude.

We studied the effect of anisotropic pore morphology on the fatigue behavior and fracture surface of lotus-type porous copper, which was fabricated through unidirectional solidification in pressurized hydrogen and argon atmospheres. The fatigue strength at finite life is closely related to the pore morphology. The fatigue strength decreases with increasing porosity, and the strength depends on applied-stress direction. The fatigue life is the longest in the direction parallel to the longitudinal axis of cylindrical pores. The fatigue strength at finite life is proportional to the ultimate tensile strength and can be expressed by a simple power-law formula. Anisotropic pores affect the fracture surface of lotus copper; crack-initiation site depends on applied-stress direction, and the anisotropic shape pores affect the direction of crack propagation and final fracture surface.

Li2MgN2H2 can reversibly store more than 5.5 wt% hydrogen. However, the high activation energy of hydrogen desorption poses a kinetic barrier for low-temperature operation. In this work, the composition of the Li–Mg–N–H system has been modified by the partial substitution of Mg or Li by Na. The changes in structure and hydrogen absorption/desorption kinetics have been investigated. It was found that the peak temperature for hydrogen desorption was decreased by ∼10 °C, and that the hydrogen absorption/desorption isotherms were also significantly changed. Furthermore, the activation energy calculated by the Kissinger’s approach was reduced after the substitution of Mg or Li by Na. In addition, the different dehydrogenation structures were detected at different molar ratios of Mg, Li, and Na.

A new Ti-based bulk-metallic glassy (BMG) alloy without Ni was developed in various forms such as melt-spun ribbon and cylindrical rods. Ti metal and Ti-based alloys are well known as biomaterials because Ti has good biocompatibility with the human body. We examined mechanical and chemical properties of a newly developed Ti-based BMG alloy in comparison with pure Ti metal and Ti–6Al–4V alloy, which are used for biomaterials. The new Ti-based BMG (Ti45Zr10Pd10Cu31Sn4) alloy does not contain Ni, Al, and Be elements, which are known to be toxic. The Ti45Zr10Pd10Cu31Sn4 BMG alloy rod with a diameter of 3 mm, which is produced by copper mold casting, exhibits a compressive strength of 1970 MPa and a Young’s modulus of 95 GPa. In addition, the Ti45Zr10Pd10Cu31Sn4 BMG alloy shows a supercooled liquid region of 56 K and a reduced glass-transition temperature, Trg(=Tg/Tl), of 0.56. The high thermal stability of supercooled liquid has enabled the fabrication of a cylindrical rod specimen with a diameter of 4 mm. This alloy exhibits precipitation of a primary nanoscale icosahedral phase upon devitrification followed by the formation of a metastable unidentified phase. Ti2Cu and Ti3Sn are stable phases formed in this alloy. The Ti45Zr10Pd10Cu31Sn4 BMG alloy has a high corrosion resistance and is passivated at a lower passive current density of approximately 10−2 A/m2 compared to those of pure titanium and the Ti–6Al–4V alloy in 1 mass% lactic acid and phosphate-buffered saline solutions at 310 K.

The densification behavior of 20–40-nm graphite-coated B4C nano-particles was studied using dilatometry, x-ray diffraction, and electron microscopy. The sintering onset temperature was higher than expected from a nanoscale powder (∼1500 °C); remnant B2O3 kept particles separated until B2O3 volatilization, and the graphite coatings imposed particle-to-particle contact of a substance more refractory than B4C. Solid-state sintering (1500–1850 °C) was followed by a substantial slowing of contraction rate attributed to the formation of eutectic liquid droplets more than 10× the size of the original nano-particles. These droplets were induced to form well below the B4C-graphite eutectic temperature by the high surface energy of nanoparticles. They were interpreted to have quickly solidified to form a vast number of voids in particle packing, which in turn, impeded detection of continued solid-state sintering. Starting at 2200 °C, a permanent and interconnected liquid phase formed, which facilitated rapid contraction by liquid phase sintering and/or compact slumping.

The aim of the present work was to study the morphological, structural, and chemical analysis as a function of depth in vanadium alloys with a 5 at.% of titanium implanted at 673 K with 1.2 keV N+ ions, by transmission electron microscopy (TEM), glow discharge (GD) analysis, and x-ray photoemission spectroscopy. These results are correlated with those of previously published nanoindentation tests, and the species and chemical states responsible for the increase in hardness are identified. The maximum increase in hardness corresponds to the highest N concentration, measured by both photoemission spectroscopy and GD. In addition, the thickness of the layer (≈1000 nm), where structural modifications are observed using TEM, can also be directly correlated with the thickness of the implanted layer, where an incremental increase in hardness has previously been measured. These findings support the conclusion that the formation of vanadium and titanium nitride/oxynitrides (–N–O,–O–N–H) compounds are responsible for the increased hardness of these V–5at.% Ti samples implanted with N at low ion energy and high sample temperature.

Thick and crack-free Pb(Zr,Ti)O3 [PZT] films were fabricated on platinized silicon substrates by a multisputtering technique. The PZT films were deposited on the Si substrate by the radio frequency magnetron sputtering method using a single oxide target. As the film became thicker, its grain size increased. Therefore, the microstructure of the film was able to be controlled by repeatedly depositing thin layers. In addition, by using a seed layer with the same composition but a much smaller grain size, it was possible to further reduce the grain size of the film. When the film had a small in-plane grain size and a fibrous columnar structure, it was highly resistant to cracking, presumably because of its enhanced strength and structural stability. By exploiting these phenomena, highly dense, crack-free, and thick PZT films were successfully deposited up to a thickness of about 5 μm. The evolution of the crystallographic orientation of the film as a function of its thickness was also observed and correlated with the total strain energy of the system.

Highly dense and crack-free Pb(Zr,Ti)O3 (PZT) thick films with a controlled microstructure and orientation were deposited on a platinized silicon substrate by the radio frequency magnetron sputtering method using a single oxide target. The microstructure and orientation of the films were adjusted by applying a thin (100) PZT seed layer by the sol-gel method and subsequent repeated sputtering. When a thin layer was deposited on the seed layer, the film had small grains with a columnar structure. However, as the film became thicker, it developed a large and non-columnar grain structure. Therefore, reducing the thickness of the film per deposition allowed the columnar microstructure to be maintained. The (100) orientation of the film was able to be maintained by depositing it on a (100) oriented seed layer. PZT thick films with controlled orientations and microstructures were successfully deposited up to a thickness of about 5 μm, and their ferroelectric and piezoelectric properties were characterized.

If a metal contracts upon solidification, the specific volume of a metallic liquid phase must not be smaller than that of the corresponding crystal. As molten metals have higher thermal expansion coefficients compared with those of the corresponding crystals, the intersection point of two specific-volume–temperature plots of the liquid and the corresponding solid crystalline phase by analogy with Kauzmann’s paradox for entropy could be treated as an ideal glass-transition temperature. This paper describes this phenomenon observed for a number of pure metals and gives a semiempirical criterion for the achievement of a good glass-forming ability.

The phase stability of ferroelectric, epitaxial, polydomain BaTiO3 thin films was examined using temperature-dependent x-ray diffraction (XRD) and in-plane electronic polarization measurements. The epitaxial BaTiO3 thin films were grown on MgO(100) substrates by a metal-organic chemical vapor deposition process. As-deposited and annealed BaTiO3 thin films with different domain structures were examined. Temperature-dependent plane-normal XRD analysis reveals well-defined phase transitions at 140 and 169 °C in the c- and a-oriented films, respectively. The measured Curie temperatures are consistent with those predicted by Landau-Ginsburg-Devonshire theory as applied to polydomain BaTiO3 thin films. Temperature-dependent in-plane electronic polarization measurements confirm that the 140 °C Curie temperature observed in the c-oriented film is a well-defined second-order paraelectric-ferroelectric transition.

A new soluble synthetic route was developed to fabricate thin films of layered structure transition metal dichalcogendies, MoS2 and WS2. High-quality thin films of the dichalcogenides were prepared using new soluble precursors, (CH3NH3)2MS4 (M = Mo, W). The precursors were dissolved in organic solvents and spun onto substrates via both single- and multistep spin coating procedures. The thin films were formed by the thermal decomposition of the coatings under inert atmosphere. Structural, electrical, optical absorption, thermal, and transport properties of the thin films were characterized. Surface morphology of the films was analyzed by atomic force microscopy and scanning electron microscopy. Highly conductive and textured n-type MoS2 films were obtained. The measured room temperature conductivity ∼50 Ω−1 cm−1 is substantially higher than the previously reported values. The n-type WS2 films were prepared for the first time using solution-processed deposition. WS2 displays a conductivity of ∼6.7 Ω−1 cm−1 at room temperature.