A series of alkali tungsten bronzes are non-stioichometric compounds having a general formula RxWO₃, where R is H, Li, Na, K and Rb and x is less than unity. They show metallic conduction. The present work was done in order to obtain highly conductive glass-ceramic. films containing tungsten bronze and to investigate their electric conductivites. A series of glasses consisted of the compositions containing 30.0-37.5 Na₂O⋅57.5-67.5 WO₃⋅2.5-10.0 B2O3 (in mol%). About 70 grams batches corresponding to the nominal compositions were melted in alumina crucibles at 1000°C for 1h. The melts were rapidly quenched by the twin roller (3000rpm) to obtain clear glasses without devitrification. Glasses were ground into powders of particle size less 37μm. Films were prepared by two methods. One was the method by dipping of a quartz glass plate into water dissolved Na₂O-WO₃-B₂O₃ glasses. The other was the method by melting the glass powders uniformly dispersed on a quartz glass plate in ethanol. Tungsten bronze crystals precipitated from these films when heat-treated in a H₂ atomosphere. These glass-ceramic films were shown to be much higher electric conductivities than the sintered tablet. The maximum conductivity of these glass-ceramic films was about 10³S/cm at 25°C. The charge carrier of glass-ceramic films was confirmed to be electron by the Seebeck coefficient measurements. The conduction mechanism of glass-ceramics was considered to be electronic conduction due to the large polaron.

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Reactivity of porous glass with organosilicones, alcohols, cyclic compound and organohalogens was studied. The density of the introduced organic functional groups from the reaction of organosilicones without steric hindrance was 2.5-4.5μmol·m^-2. On the other hand, the density decreased to 20-50% by the reaction of organosilicones with steric hindrance such as dimethyloctadecylchlorosilane and triphenylchlorosilane. The density of the organic functional groups from the reaction of alcohols was 2.77-7.75μmol·m^-2, except for t-butanol. When porous glass was treated with alcohols, the density depended on the pore structure of porous glass. The porous glass had a slight reactivity with iodides, but no reaction was observed with bromide and chloride.

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The glass-forming region was determined by the water quenching method in the system Na₂O-Ga₂O₃-B₂O₃. Raman spectra were measured for glasses in the composition range 10-40mol% Na₂O, 0-30mol% Ga₂O₃ and 30-90mol% B₂O₃. The Raman spectroscopic study revealed that, at a given Ga₂O₃ concentration, an increase in Na₂O content causes changes in boron coordination in the sequence BO₃→BO₄→BO₃, while for a given Na₂O concentration an increase in Ga₂O₃ content reduces the BO₄ concentration in the Na₂O-Ga₂O₃-B₂O₃ glass. Change in coordination number of gallium from 6 to 4 was deduced from the Raman spactra. The compositional dependence of density and refractive index consistent with the deduced structural changes in glass.

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Fine mullite powders with a stoichiometric composition were prepared by ultrasonic spray pyrolysis of a mixed alcoholic solution of tetra-ethyl-ortho-silicate (TEOS) and aluminum-iso-propoxide (Al (iso-OPr)₃). In this process, pre-treatment of a starting alkoxide solution played an important role in mullite formation. TEOS was partially hydrolyzed using HNO₃ catalyst and co-polymerized with Al (iso-OPr)₃. This pre-treated starting solution gave a precursor having a uniform composition in the intermediate stage of spray pyrolysis. The precursor from solutions with the H₂O/TEOS molar ratios of above 5 contained many Al-O-Si bonds as a framework of mullite structure, and heating resulted in a homogeneous mullite powder without forming spinel phase. For the molar ratios below 4, on the other hand, the precursor crystallized to a spinel phase in the first step of_heating, transformed to the mullite phase, and then separated α-Al₂O₃ at higher temperature. Starting solutions without pre-treatment as above discribed gave mixtures of mullite and α-Al₂O₃. Mullite prepared under the above optimum condition had no compositional fluctuation througtout the particle.

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Effects of Al₂O₃ addition on the mechanical properties and microstructure of Y-TZP were studied. Specimens of 2.5mol% Y₂O₃-doped ZrO₂ containing 0.375-1.5mol% Al₂O₃ were prepared by pressureless sintering at 1400°-1550°C, and the density, bending strength, fracture toughness (K_IC), Vickers hardness and microstructure were examined. Addition of Al₂O₃ improved the relative density, bending strength, hardness and fracture toughness. The amount of cubic phase increased with increasing Al₂O₃ content for specimens sintered between 1500°-1550°C.

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ZrO₂, TiO₂ and ZrTiO₄ films were prepared from sols of crystalline fine particles of ZrO₂ and TiO₂ by drying on glass substrates and firing gel films which were separated from the substrates. Then separate polycrystalline films (10-20μm thick) of PbZrO₃, PbTiO₃ and Pb (Zr, Ti) O₃ were synthesized by heating ZrO₂, TiO₂ and ZrTiO, films, respectively, with lead acetate or lead oxide. Grain orientation was observed in the PbZrO₃ and PbTiO₃ films, but not in the Pb (Zr, Ti) O₃ film. The orthorhombic b-axis in the PbZrO₃ film and the tetragonal c-axis in the PbTiO₃ film were perpendicular to the film plane. The orientation of PbZrO₃ depended on the orientation of ZrO₂ crystals, whereas the orientation of PbTiO₃ was independent of orientation of TiO₂ crystals and depended on the flatness of the polycrystalline surface of TiO₂. It was supposed that the oriented PbTiO₃ crystals are formed by crystallization and growth in a thin liquid phase on the film surface.

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Homogeneous precursor powders for obtaining cordierite composites with uniformly dispersed mullite particles were prepared by partial hydrolysis of alkoxides. The precursor powders crystallized into mullite and MgAl₂O₄ at 900°C. Cordierite crystal was formed above 1200°C, which was formed through the solid-solid reactions among MgAl₂O₄, β-quartz solid solution, sapphirine and unknown phases. The crystalline phases in the composites sintered above 1300°C were cordierite and mullite. The dense composite containing 40mol% mullite which was obtained by firing at 1300°C for 2h had the mean 4-point bending strength of 125MPa and the thermal expansion coefficient of about 3.1×10^-6/°C, respectively.

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Single crystals of Al_xCu_yB₁₀₅ (hexagonal system, space group: R 3m) were prepared by the reaction between metals and elemental boron using a molten copper flux in an argon atmosphere. The conditions for obtaining one-phase materials were determined. As-grown Al_xCu_yB₁₀₅ single crystals were used for chemical analysis, and measurements of lattice constants, density and Vickers microhardness. The optimum mixing atomic ratio of the starting materials (B/Al and B/Cu), heating temperature and soaking time are B/Al=4/2, B/Cu=4/20, 1500°C, and 3h, respectively. Under these conditions, the single crystals were obtained in the form of an irregular or rhombohedral plate: the latter crystals were bounded by {001} planes. The single crystals had metallic luster of silver (Al_2.8Cu_2.9B₁₀₅) or grayish brown (Al_3.7Cu_0.8B₁₀₅) color. The results of themical analysis and the measurements of lattice constants and densities (d_m) are as follows: Al_2.8Cu_2.9B₁₀₅; a_hex.=10.9993 (5) (Å), c_hex.=23.9659 (8) (Å), V=2511.0 (2) (ų), d_m=2.70 (2)g/cm³ Al_3.1Cn_1.7B₁₀₅; a_hex.=10.9946 (4) (Å), c_hex.=23.9530 (12) (Å), V=2507.6 (2) (ų), d_m=2.58 (1)g/cm³ Al_3.7Cu_0.8B₁₀₅; a_hex.=10.9803 (3) (Å), c_hex.=23.9298 (12) (Å), V=2498.6 (2) (ų), d_m=2.48 (2)g/cm³ Average values of Vickers microhardness determined on {001} faces of Al_xCu_yB₁₀₅ single crystals fell in the range 2530-3130kg/mm².

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The thermal decomposition of lutetium (III) acetate tetrahydrate has been studied by TG, DTA, DSC, X-ray diffraction, infrared spectroscopy, gas chromatography and chemical analysis. The tetrahydrate decomposes to anhydrous acetate at 60°C. The anhydrous acetate shows a reversible transition between 245° and 255°C with the heat of transition of 8.62kJ/mol. The anhydrous acetate releases acetone and carbon dioxide and decomposes to lutetium (III) oxide through an intermediate compound in the temperature range of 300° and 640°C. The compound belongs to the tetragonal system with the estimated composition of Lu₂O₂CO₃.

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A glaze containing 8wt% Fe₂O₃ was fired in various atmospheres with the same firing schedule. The effect of firing atmosphere on the color of the iron glaze was studied with a color analyzer, and by ESR, X-ray diffraction, and EPMA.
(1) The glaze fired in oxidizing atmospheres was black irrespective of the firing conditions, but the color of glaze fired in reducing atmospheres varied with the onset temperature of reduction.
(2) The color of the glazes which were reduced at 900° or 1000°C was black with red spots. The glazes which were reduced at 1100° and 1200°C were red and black, respectively.
(3) The results of ESR, X-ray diffraction and EPMA suggested that the black color of the glaze fired in oxidizing atmospheres was caused by the coexisting Fe³⁺ and Fe²⁺ ions. The black and the red colors in the glaze fired in reducing atmospheres were due to aggregated metallic iron and aggregated Hematite, respectively.

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A new method for determining the two-dimensional compositional fluctuation region in a ternary solid solution Pb{(Zr_xTi_1-x)_1-y(Mg_1/3Nb_2/3)y}O₃ (PZTMN) was developed. Problems in determining the compositional fluctuation region in the previously-reported method, where fluctuations in x and those in y can be determined independently, are discussed. In this new method, diagrams of equal lattice spacing lines in the ternary system were prepared for various diffraction planes. The fluctuation limits of lattice spacing of these planes were determined by X-ray diffraction analysis. Lines of compositions of which lattice spacing is the fluctuation limit were drawn in the ternary diagram. The compositional fluctuation region is seen to abut on all these lines.

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PbTiO₃ films were prepared by simultaneous deposition of TiO₂ and PbO on heated substrates under atmospheric pressure. Titanium tetra-isopropoxide and tetra-ethyl lead were used as source materials. For estimating the optimum condition on the preparation of PbTiO₃ films, the deposition behavior of TiO₂ and PbO was examined independently. The films obtained at 500°-600°C consisted of PbTiO₃ of perovskite structure. The rate of film deposition at 600°C was 200Å/min, about ten times faster than that by conventional sputtering method. Si(100), sapphire (0001) and MgO(100) were used as substrates, and the films on MgO(100) showed strong c-axis orientation. The dielectric constants of the films on Si were 100-130, in agreement with the value of ceramics or sputtered films.

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Directionally solidified ingots of the eutectic composition and its neighboring compositions in the system (Bi₂O₃)_0.85(Nb₂O₅)_0.15-6Bi₂O₃⋅SiO₂ are expected to show chatoyancy like natural cat's eye stone, since they have structures in which fibrous δ-(Bi₂O₃)_0.85(Nb₂O₅)_0.15 crystals of higher refractive index are aligned parallel in a γ-6Bi₂O₃⋅SiO₂ crystal matrix of lower refractive index. The chatoyancy of the ingots was investigated in terms of their microstructure. An eutectic ingot solidified with a single crucible (Ref. 1) showed the chatoyancy only at a low solidification rate, regardless of the composition of the ingot (Figs. 2 and 3). An eutectic ingot solidified with double crucibles (Ref. 2) showed a chatoyancy even at a fairly high solidification rate, and especially sharp and clear one at a low solidification rdte (Fig. 4). Clearness of the chatoyancy of the ingots could be interpreted in terms of average diameter of cells in which the fibrous crystals are aligned almost completely parallel (Fig. 8). The fraction of parallel-aligned fibrous crystal increases with increasing cell diameter, resulting in sharp and clear chatoyancy (Fig. 9).

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The dispersability of Si₃N₄ powder in n-C₆H₁₄ and Al(Oi-Pr)₃/n-C₆H₁₄, and the amount of Al(Oi-Pr)₃ adsorbed on the surface of Si₃N₄ particles after mixing Al(Oi-Pr)₃/n-C₆H₁₄ and Si₃N₄ were examined. The zeta-potential of the powder prepared by spray-drying and calcining a mixture of Al(Oi-Pr)₃/n-C₆H₁₄ and Si₃N₄ was measured. The dispersablity of Si₃N₄ in Al(Oi-Pr)₃/n-C₆H₁₄ was much higher than in n-C₆H₁₄, due to the formation of-Al(Oi-Pr)_n layer on Si₃N₄ particle surfaces. The Si₃N₄ powder which was separated from the mixture of Al(Oi-Pr)₃/n-C₆H₁₄ and Si₃N₄ by filtration after hydrolysis by addition of water and peptization by addition of diluted HCl at pH 2, contained 0.07wt% Al. The isoelectric point of the powder which was prepared by spray-drying and calcining the mixture of Al(Oi-Pr)₃/n-C₆H₁₄ and Si₃N₄ was about 8.2, while that of Si₃N₄ was 5.5. These results suggested that Si₃N₄ particles were coated with a γ-Al₂O₃-like layer.

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Hot-pressed silicon nitride specimens were oxidized in air flow at 1200°C for up to 3000h. Tridymite was detected by X-ray diffraction after 750h oxidation, and the crystals of 3-4×200-300μm were observed by composition image on the 3000h oxidized layer. The composition change in the phases by oxidation were examined with an EDS. The relative amount of SiO₂ in the Y2S phase decreased during oxidation leading to the stoichiometric composition (Y₂O₃⋅2SiO₂). The glassy phase formed after 3000h oxidation contained several metallic oxides such as Y₂O₃, CaO, MgO, Na₂O, K₂O and 10wt% Al₂O₃. Incorporation of alkali and other metallic oxides into the glassy phase lowered the melting temperature of the silica (cristo balite)-rich phase. The glassy phase acted as a flux of silica to promote the crystallization of tridymite.

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¹¹B- and ¹⁰B-containing apatites were prepared from the system CaO-P₂O₅-B₂O₃ at 1000°C. The structure of borate groups was investigated by infrared spectroscopy based on isotopic frequency shifts. The boron-containing apatite has both BO₂ and BO₃ groups, but it does not contain BO₄ groups. The BO₃ groups occupy PO₄ site of the apatite structure.

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Ba₂YCu₃O_x films were prepared from inorganic and organic acid salts to investigate the influences of starting materials on the superconducting transition. All films derived from acetates, nitrates and long-chain organic acid salts, as well as those from 2-ethylhexanoates reported previously, showed high T_c superconducting transition after heated at 800°C in pure oxygen atmosphere. The dependence of T_c values on the oxygen content required of the starting materials in pyrolysis shows that annealing depends on the starting materials. This is probably related to the concentration of the oxygen defects and/or the crystallization process of high-T_c phase.

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Superconducting properties of SrCaBiCu₃O_x ceramics have been studied. The ceramics sintered at 820°C showed a two-step superconducting transition at 117K and 64K. The ceramics sintered at 900°C had the highest transition temperature, i.e. T_{c, zero}=80K. The Sr-Ca-Bi-Cu-O system is considered to contain a phase with superconducting transition temperature (above 100K) higher than that in Ba-Y-Cu-O systems. The melting point of this material is 875°C. The weight loss due to oxygen removal which occurred in Ba-Y-Cu-O system was not observed up to 850°C. X-ray diffraction analysis and microstructure observation were examined.

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