Crystalline orientation and growth rate of titanium dioxide polycrystalline films deposited using an air-opened chemical vapor deposition apparatus were investigated. The deposition rate of the titanium dioxide films depends on the substrate temperature and the vaporizing temperature of titanium tetra-isopropoxide. X-ray diffraction analysis revealed that the growth orientation of the films was mainly varied with the vaporizing temperature. At relatively low vaporizing temperature, the films were consisted of ‹001›-oriented columnar crystals grown at a minimum deposition rate of 4nm/s. In contrast, ‹100›-and ‹211›-oriented crystallites grew with a maximum deposition rate of 45nm/s at relatively high vaporizing temperature. These results suggest that the concentration of reactant, which is strongly dependent upon the vaporizing temperature, is one of factors which decide the growth rate of each crystal face.

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Organic-inorganic hybrid coating films were prepared using vinyltriethoxysilane and tetraethoxysilane by the sol-gel method on polyimide substrates. Tetraethoxysilane (TEOS) and vinyltriethoxysilane (VTES) or polyvinyltriethoxysilane (PVTES), which was obtained by the radical polymerization of VTES, were used as starting materials. In the TEOS-PVTES system, the organic-inorganic hybrid films with both carbon-carbon and siloxane bonds were obtained, and PVTES gave crack-free and flexible films over a wide composition range. It was found that the Si-O-Si bonds in the organic-inorganic hybrid films contributed to the increase in the dynamic hardness, while the smoothness of the coating films prepared using PVTES contributed to the increase in the pencil hardness.

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Using two types of polycarbosilane-derived SiC fibers, namely, Hi-Nicalon (1.8mass% oxygen) and Nicalon NL400 (13mass% oxygen) changes in their properties and the mechanism of deterioration were investigated at 1873K. A short period pyrolysis changed rapidly the properties such as gas generation, tensile strength, crystallite size of β-SiC and specific resistivity. The pyrolysis and the resultant crystal growth proceeded from the surface to the core of Nicalon. The fiber strength was proportional to the reciprocal square root of crystallite size. The formation of surface flaw, as well as coarsening of crystals, was an important factor controlling the fiber strength. Nicalon, which was porous after pyrolysis, deteriorated severely. On the other hand, Hi-Nicalon retained high levels of strength because of slow crystal growth and suppressed gas liberation.

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A birnessite-type sodium manganese oxide with a layered structure was synthesized by the reaction of Mn(NO₃)₂ solution with a mixed solution of H₂O₂ and NaOH at room temperature. This sodium manganese oxide was hydrothermally treated in neutral, acidic and alkaline solutions at 150°C. The original samples which were synthesized at room temperature and hydrothermally treated samples were characterized by XRD, DTA-TG, FT-IR spectroscopy and chemical analysis. The formation of the birnessite-type sodium manganese oxide is dependent on the mixed mole ratio of NaOH/Mn(NO₃)₂. The fraction of the birnessite phase increased with increase in mixed mole ratio of NaOH/Mn(NO₃)₂. The birnessite-type manganese oxide has a basal spacing of 1.004nm before air-drying, but it changes to 0.724nm after the air-drying at room temperature. A well crystallized birnessite phase with a basal spacing of 0.724nm was obtained by hydrothermally treating the birnessite-type sodium manganese oxide prepared at room temperature with a NaOH solution.

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Thick silica films were prepared on the cathode by the electrophoretic sol-gel deposition using a cationic polymer surfactant, polyethylenimine (PEI). The weight of the silica particles deposited on the cathode was maximized when the content of PEI added was 0.01mass% and pH of the coating sols was 5. As the amount of PEI added increased over the optimum content (0.01mass%), the weight of the silica particles deposited decreased with an increase in PEI content because of H₂ generation at the cathode and the aggregation and precipitation of silica particles in the coating sols. Thick silica films obtained had no cracks and the thickness was ca. 20μm.

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An investigation has been made on the hydrolysis behavior of vanadyl isopropoxide, VO(O-i-C₃H₇)₃, in which a wide range of hydrolysis water content (0<r (=[H₂O]/[VO(O-i-C₃H₇)₃])<500; in molar ratio) and alkoxide concentration (0<q (=[VO(O-i-C₃H₇)₃]/[i-C₃H₇OH])<0.08) were used to be examined. It has been found that there exists a viscous solution phase in a rather high water content region; r>200, along with its known phases of liquid, precipitate and gel below this level of water content. All the phases of precipitate, gel and viscous sol in the VO(O-i-C₃H₇)₃-H₂O-i-C₃H₇OH system were confirmed by X-ray diffraction analysis to contain primary particles with nearly the same crystal structure. Using a precursor solution (unhydrolyzed) and a viscous sol solution of VO(O-i-C₃H₇)₃, thin films of vanadium oxide were prepared on SiO₂/Si substrates by spin coating, followed by firing at 450°C in air. A comparison has been made between the two vanadium oxide films obtained in terms of their surface morphologies, and it has been confirmed that the viscous solutions have an advantage over the precursor solution in using as a coating solution for producing vanadium oxide thin films of good quality.

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CaO-SiO₂ gel was prepared from Ca(NO₃)₂ and TEOS. The mixture of TEOS, Ca(NO₃)₂, H₂O and EtOH was immiscible at first, but became miscible by stirring for several hours. Wet gels containing 10-60mol%CaO were formed and dry gels were amorphous at the composition of 10-40mol%CaO. It was found that a small amount of Ca(NO₃)₂ crystal precipitated in dry gels can react with SiO₂ gel by heat treatment and the heat-treated gels were amorphous. The reaction of Ca(NO₃)₂ with SiO₂ gels was confirmed by disappearance of IR absorption peak attributed to NO₃^- ion after heat treatment. The gels in the immiscibility region in this system (10, 20mol%CaO) caused phase separation by heat treatment at 600-800°C. The tendency of phase separation was high for high CaO content gels. The crystallization behavior of gels in the immiscibility region was found similar to that of CaO-SiO₂ amorphous films prepared by sputtering method.

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Si₃N₄ ceramics can be obtained by nitridation of Si powder compact accompanying a little volume change. Elucidating the nitridation mechanism of Si particle is important to control the form of Si₃N₄ particle. In this work, TEM analysis of the initial stage of nitridation of Si particle was conducted, and following are concluded; (a) at the initial stage of nitridation of Si particle, at temperature between 1100 to 1250°C, 10nm to 50nm thickness of Si₃N₄ layer is formed between the Si body and the surface oxide layer, which indicates the nitriding velocity is low. (b) the Si₃N₄ layer becomes thinner with decreasing the radius of Si particle. (c) The nitridation mechanism of Si particle can not be explained by linear-parabolic model, and it suggests that not only the diffusion velocity of N₂ and the reaction velocity of Si and N₂. (d) The volume expansion of Si₃N₄ shell leads a radius compressive stress and circumferential tensile stress, which are proportional to the third power of a particle radius. The radius compressive stress increases with decreasing the radius of Si particle, and it controls a nitriding velocity.

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ZrO₂-dispersed MgO-Al₂O₃ ceramics with various MgO to Al₂O₃ compositional ratios were prepared from Mg(OH)₂ powder, α-Al₂O₃ powder and Zr-n-butoxide by calcining at 1000°C for 2h and sintering at 1600°C for 1h. The influence of the MgO-Al₂O₃ compositional ratio on the sinterability and mechanical properties was studied. Addition of 10vol% ZrO₂ improved the relative density of the sintered specimens containing 50 and 62.5mol% Al₂O₃. However, the addition was not effective at other compositional ratios. The bending strength was improved at composition containing more than 50mol% Al₂O₃, where the dispersed ZrO₂ particles were in the form of tetragonal phase. The bending strength increased with increase in Al₂O₃ content in the ZrO₂ dispersed specimens. The fracture toughness was improved for all specimens by ZrO₂ dispersion, especially, for the specimen in which MgO-Al₂O₃ component was in a single crystalline phase.

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Influence of humidity on the electrical conductivity on sol-gel derived amorphous titanium phosphate oxide films of nominal compositions of 1TiO₂⋅9P₂O₅ to 9TiO₂⋅1P₂O₅ (molar ratio) was investigated. The surface resistivity of a 3TiO₂⋅7P₂O₅ film showed two order dependence on relative humidity change from 50RH% to 90RH% at 30°C. The surface conductivity of this film was 10^-3S·cm^-1 at 30°C, 90RH%. It is higher than that of alkaline-earth phosphate glasses (10^-5S·cm^-1 at around 100°C). Furthermore, the electrical resistance of this film decreased about one order after keeping it in a high humidity atmosphere of 90RH% at 30°C for 2.5h. This phenomenon implies that the proton conductivity was much enhanced by a large amount of molecular water (recognized at 3250cm^-1 in FT-IR spectrum) which incorporated into the glass structure.

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Preparation of SrTiO₃ ceramic foam from alkoxide-derived oxide green sheets containing polymer microspheres via polymer extraction has been studied. SrTiO₃ suspension in aqueous media was prepared by hydrolysis of Sr(OC₃H₇ⁱ)₂ and Ti(OC₃H₇ⁱ)₄. Polystyrene microspheres and PVA (poly (vinyl alcohol)) were added to this suspension (weight ratio: SrTiO₃/polystyrene/PVA=100/60/8), and then precursor green sheets were produced. Polystyrene microspheres were incorporated in the SrTiO₃ matrix phase in this green sheets. The polystyrene microspheres were extracted with organic solvent from the green sheets before the heat treatment. The dimension of the green sheets was not changed by the extraction of the polystyrene microspheres. Ceramic foam with spherical pores could be obtained by the heat treatment of the green sheets after extracting the polystyrene microspheres. Linear shrinkage of the sheets observed in the heat treatment was 20%.

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Zinc selenide (ZnSe) was synthesized by thermal decomposition of metal alkoxide at temperatures as low as 400°C. The influences of alkoxide species and their decomposing atmosphere have been investigated. Thermal decomposition was carried out in three different atmospheres: Air, N₂ and CO(CO/N₂=1/4). Zn-Se double alkoxides, which were prepared by the reaction of Na-Zn alkoxide with selenium tetrachloride, produced a phase of ZnSe of zinc-blend structure by its thermal decomposition in CO atmosphere. The resulting ZnSe particles were needlelike shape and had lengths from 3 to 10μm. When the Zn-Se double alkoxides were decomposed in Air or N₂ atmosphere, ZnO was obtained with traces of Na₂SeO₄. Thermal decomposition of mixture of Na-Zn alkoxide and Se alkoxide in CO atmosphere did not produce ZnSe. The formation of ZnSe was discussed based on thermodynamic data.

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A focused ion beam (Ga⁺-FIB) drawing on a non-conductive ceramic substrate was investigated for the formation of finely electrified images. The electrified images were formed by using a 30kV of Ga⁺-FIB with a drawing pattern equipment. The region irradiated with Ga⁺ ions on the substrates showed positive surface potential and the decay rate of the surface potential was less than 10% for 2000s in air. The electrified images were in-situ observed with a scanning electron microscope (SEM) at 2.5kV. The secondary electron images, namely the voltage contrast images, showed dark contrast. This fact indicates that the dark image corresponds to the positively electrified regions on the substrate. The width of the electrified image was 8μm. Finely electrified images formed by Ga⁺-FIB can be applied to the electrostatics processes.

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Bubble-free, transparent Li₂B₄O₇ single crystals were grown by a newly developed pulling-down method. The use of a two-zone vertical furnace with a Pt-crucible realized a relatively steep temperature gradient of about 50°C/cm around the growth interface and a moderate gradient of about 13°C/cm below the interface, contributing to prevent grown crystals from cracking. Even at a pulling-down rate of 0.75mm/h, which is higher than that in the Czochralski growth, the formation of bubbles was effectively suppressed at a rotation rate of 25rpm. Any crystals grown along [110] direction involved no low-angle grain boundaries, but twinning was occasionally recognized. The dislocation density in the initial part of the crystal growth was found to be about 5×10³/cm² from an etch pit pattern, while X-ray topography of a vertical cross section revealed that the number of dislocation lines decreased as the growth proceeded.

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A new viscometer, uniform speed penetration viscometer, was constructed with which the viscosity of glass melts can be measured in the range of 10²-10⁸Pa·s. A pin dipped in the melt was penetrated into the melt with a uniform speed and the viscous drag on the pin was measured. A calibration curve between the viscous drag and viscosity was prepared using NBS711 glass as a standard material. The viscosity of glass melt can be determined from the measured viscous drag and the calibration curve. It was ascertained that the viscosities of lead-silicate glasses can be measured by this viscometer in the range of 10²-10⁸Pa·s, and that they agree well with the Littelton point measured by another method. The limits of measurement at high and low viscosities were analyzed and discussed based on the interface phenomena between the pin and the melt.

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A possibility of artificial fabrication of ceramic model tooth which has a machinability similar to natural human tooth was experimentaly discussed. Comparison among many physical properties and the machinability of ceramic model tooth with the natural human tooth showed that such a model tooth can be made artificially. Then important factors were pointed out, i.e., (1) proper combination and blending of raw materials for ceramic commercial porcelain, and (2) proper controlling of firing temperature for densification.

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Dole assumed first that pH-glass electrode is semipermeable only to hydrogen ions. However, Hammond disproved Dole's assumption by his experiment. The recent theories for pH-glass electrode generally accepted so far have been based on the assumption that hydrogen ions do not cross the glass. Some doubts and comments are presented to the theories from our viewpoint that is based on the high mobility of hydrogen ion in the pH-glass electrode.

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β-Si₃N₄ containing 0.5mol%Y₂O₃ and 0.5mol%Nd₂O₃ was seeded with 5mass% β-Si₃N₄ whisker with high aspect ratio and extruded to align the whiskers. Self-reinforced microstructure composed of well-aligned large elongated grains in smaller matrix grains was developed by the grain growth of seeded whiskers during gas-pressure sintering at 2000°C in 30MPa N₂ for 4h and heat treatment at 2200°C in 30MPa N₂ for 4h. Room-temperature thermal conductivity was anisotropic; 140W·m^-1·K^-1 for parallel to the grain alignment, and 84W·m^-1·K^-1 for perpendicular to the alignment.

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