Fe(III)-doped TiO2 (anatase) was prepared by the oxidation of FexTiS2. Two calcination methods were used to oxidize FexTiS2. In the first, sulfide was calcined in air at a given temperature for 2 h. In the second method, the sulfide was heated in air at a finite heating rate (2.5 K/min) and then held at a constant temperature for 2 h. Fe(III) ions completely dissolved into TiO2 (anatase), forming Fe(III)-doped TiO2 (anatase), in the composition range of 0 ⩽ Fe/Ti ⩽ 0.3 (mole ratio). The properties of the obtained oxide depended on the oxidation method of FexTiS2. The electronic property and the valence stage of the Fe(III)-doped TiO2 (anatase) were examined. The activation energy of electronic conduction decreased with an increase of the doped amount of Fe(III) ions. The x-ray photoelectron spectroscopy result showed that the electron density on the Ti ion in the Fe(III)-doped TiO2 (anatase) was decreased by the Fe(III) doping.

A novel and simple microwave-assisted combustion procedure for the synthesis of a number of technologically important metal nitrides was demonstrated. The method involves the combustion reaction of a porous metal powder compact with N2 gas in the microwave field and provides phase-pure metal nitride products (consisting of fine particles, fibers, and whiskers) within minutes. The ignition and combustion temperatures of the reaction were found to vary as a function of compaction pressure. The microwave-prepared nitrides were characterized using x-ray diffraction, scanning electron microscopy energy dispersive spectroscopy, thermogravimetric analysis, and infrared spectroscopy. The present microwave-assisted hybrid-heating procedure allows the preparation of nitrides with good crystallinity, structural uniformity, and phase purity, and appears to have general applicability for the preparation of metal nitrides (using the respective metals or even their oxides).

Al2O3 powders with four different particle sizes were densified using a spark plasma sintering (SPS) apparatus under three different sintering conditions: holding time, heating rate, and mechanical pressure. The Al2O3 powder compact sintered at a higher heating rate produced a sample with a higher density and a fine-grained microstructure, while abnormal grain growth and a lower density resulted when a lower heating rate was applied, though the sintering temperature and holding time were the same in both cases. This revealed that rapid sintering by SPS was effective for promoting the densification of the powder. However, the powder with a coarse particle size was hard to sinter at a higher heating rate. Microstructural observation revealed that the edge part was denser than the inside of the sample when the holding time was short. Increasing the holding time made it possible for the inside to be sintered almost as dense as the edge part. Mechanical pressure was found to enhance densification of the Al2O3 powder. On the basis of these results, the SPS process is discussed.

Nanopowders of amorphous silicon nitride were densified and sintered without additives under ultrahigh pressure (1.0–5.0 GPa) between room temperature and 1600 °C. The powders had a mean diameter of 18 nm and contained ∼5.0 wt% oxygen that came from air-exposure oxidation. Sintering results at different temperatures were characterized in terms of sintering density, hardness, phase structure, and grain size. It was observed that the nanopowders can be pressed to a high density (87%) even at room temperature under the high pressure. Bulk Si3N4 amorphous and crystalline ceramics (relative density: 95–98%) were obtained at temperatures slightly below the onset of crystallization (1000–1100 °C) and above 1420 °C, respectively. Rapid grain growth occurred during the crystallization leading to a grain size (>160 nm) almost 1 order of magnitude greater than the starting particulate diameters. With the rise of sintering temperature, a final density was reached between 1350 and 1420 °C, which seemed to be independent of the pressure applied (1.0–5.0 GPa). The densification temperature observed under the high pressure is lower by 580 °C than that by hot isostatic pressing sintering, suggesting a significantly enhanced low-temperature sintering of the nanopowders under a high external pressure.

Structural studies of the strontium vanadate glasses of compositions xV2O5–(100 − x)SrO are reported. X-ray diffractograms, density, and oxygen molar volume, etc., of the glasses show that single-phase and homogeneous glasses were obtained in the composition domain x = 50 to 90 mol%. The network structure for the glass compositions with 90 and 80 mol% V2O5 is built up of the VO5 polyhedra, while the other glass compositions consist of the VO4 polyhedra. Density and glass transition temperature are observed to decrease with an increase in the V2O5 content. The magnetic susceptibility of the glasses shows an increase of concentration of the reduced V4+ ion with the increase of vanadium oxide content in the compositions. The well-resolved electron spin resonance structure observed for the glass composition with 50 mol% V2O5 gradually becomes poor and reduces to a single component line, which has been attributed to the increase of the hopping rate of charge carriers with the increase of the V2O5 content in the compositions.

A new equation was developed for evaluating kinetic parameters in the isokinetic range of a phase transformation using nonisothermal calorimetric techniques. The Johnson–Mehl–Avrami equation was extended by considering that the transformation rate in an isothermal process can be translated into the nonisothermal transformation in an isokinetic range. The Avrami exponent, n, activation energy, E, and frequency factor, K0, were calculated from only one nonisothermal experiment by using the new kinetic equation for amorphous Se (a-Se), polysilane/polycarbosilane (PS/PCS), and lithium disilicate (LiO2 · 2SiO2 or LS2) samples with nucleation site saturation. The values of E and K0 calculated using the new kinetic equation agree well with those obtained by the Kissinger equation for the prenucleated a-Se, PS/PCS, and LS2 samples. The values of n indicate that volume crystallization is dominant in the bulk a-Se and LS2 samples, whereas surface crystallization is dominant in the powdered PS/PCS sample. These results for a-Se were confirmed by scanning and transmission electronic microscopy.

An ultrahigh vacuum (UHV) diffusion bonding/deposition instrument was designed and constructed, which can produce homophase and heterophase planar interfaces from a wide array of materials. The interfaces are synthesized in situ by diffusion bonding of two substrates with or without various interfacial layers, at temperatures up to about 1500 °C. Substrate surfaces can be heat treated, ion-beam sputter cleaned, and chemically characterized in situ by Auger electron spectroscopy prior to deposition and/or bonding. Bicrystals can be synthesized by bonding two single-crystal substrates at a specified orientation. Interfacial layers can be deposited by electron beam evaporation and/or sputter deposition in any layered or alloyed combination on the substrates before bonding. The instrument can accommodate cylindrical and/or wafer type specimens whose sizes are sufficient for fracture mechanical testing to measure interface bond strength. A variety of planar interfaces of metals, semiconductors, and ceramics were synthesized. Examples of bonded stainless steel/Ti/stainless steel, Si/Si, and sapphire/sapphire interfaces are presented.

The role of a soft adhesive interlayer in determining critical conditions for fracture in brittle layer structures from indentation with hard spheres is investigated. A model transparent trilayer system consisting of a glass plate overlayer (thickness range 80 μm to 2 mm) joined to a glass plate underlayer (thickness 5.6 mm) by an epoxy adhesive (thickness range 5 μm to 8 mm), loaded at its top surface with a hard tungsten carbide sphere (radius 3.96 mm), facilitates in situ observations of the crack initiation and propagation. Whereas in bulk glass fracture occurs by inner Hertzian cone cracking immediately outside the contact circle, the soft adhesive allows the overlayer glass plate to flex, initiating additional transverse fracture modes within the overlayer: downward-extending outer ring cracks at the top glass surface well outside the contact, and upward-extending radial cracks at the bottom glass surface (i.e., at the glass/adhesive interface) on median planes containing the contact axis. The top and bottom surfaces of the glass overlayers are given selective prebonding abrasion treatments to ensure uniform flaw states, so as to enable accurate comparisons between crack initiation conditions. The adhesive bonding is strong enough to preclude delamination in our layer system. Of the three transverse crack systems, the subsurface radials generates most easily in systems with large adhesive thicknesses (and smaller overlayer thicknesses). Semi-empirical relations are specified for the dependence of the critical loads for radial and ring cracking on adhesive as well as overlayer thickness, based on the assumption that crack initiation occurs when the maximum tensile stresses in the flexing glass plate exceed the bulk strength of the (abraded) glass. Coupled with the traditional “Auerbach's law” for cone crack initiation, these relations afford a basis for the construction of simple design diagrams for brittle layer systems joined by adhesives.

Transmission electron microscopy and electron diffraction were used to study hardness indentations made at room temperature in ⟨001⟩-oriented single crystals of MoSi2. Two families of slip systems, {110}⟨001⟩ and {101}⟨010⟩, were identified. The first system formed ⟨001⟩ dislocation loops by prismatic punching beneath the indenter, while the second system led to large rotations of the crystal lattice beneath the indenter. The lattice rotations were used to estimate the density of dislocations stored in this volume. The results demonstrate that the hardness response of MoSi2 can be explained by the expanding cavity model with most of the plastic accommodation occurring immediately beneath the indenter.