Valence states and structures of vanadium species supported on silica, which were synthesized by a sol-gel method, were studied by Electron Spin Resonance (ESR), UV-visible absorption, diffuse reflectance, and photoluminescence spectroscopies for various stages of the process (sols, xerogels and heated xerogels). ESR measurements revealed that V⁴⁺ ions were present as [VO(H₂O)₅]²⁺ in sols and xerogels for a lower vanadium concentration, whereas a higher vanadium concentration led to the aggregation of V⁴⁺ ions in the drying stage of the sol-gel process. Upon calcinations at a higher temperature of. 873K, the V⁴⁺ ions were oxidized to V⁵⁺ which, for a lower vanadium concentration, were located in isolated pseudotetrahedral silica sites, and with an increase in the vanadium content, were aggregated so that V₂O₅ was finally formed. Changes of pseudotetrahedral structure to octahedral one by the coordination of water molecules in the atmosphere were observed, especially when. the xerogels was heated at a lower temperature of 973K.

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Two kinds of CaO clinkers, with 70% (low) density and 95% (high) density, were prepared and treated at 500-800°C in a carbon dioxide atmosphere. The low-density clinker was carbonated both on the exterior surface and inside the pores, with each CaO grain being encompassed by a layer of CaCO₃ film; whereas the high-density one was only carbonated on the exterior surface with a lower rate. The carbonation processes for both samples were controlled by the diffusion of CO₂ through the formed CaCO₃ film. The carbonation rate increased with temperature rising, and reached the maximum at 700°C. The microstructure of the formed CaCO₃ film was significantly affected by carbonation temperature, and a dense texture of CaCO₃ with grains about 2μm in thickness was obtained at 700°C. Slaking test showed that the carbonated sample with low-density was easily broken due to the weak bond among the carbonated grains in spite that the hydration resistance was improved. For the high-density sample, the hydration resistance was improved significantly after this treatment. An induction period of 7d was achieved and the sample was not broken after 21d slaking at 70°C in 90% humidity.

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IR and NMR spectra suggest the existences of the TiQ₃ (Si-O-Ti) in the prepared precursor. Quantitative estimation of the ²⁹Si NMR spectra reveals that TiQ₃ ratio in the silicon atom coordination is saturated at ca. 10mol%. Beyond the Ti/Si rario of 0.2, the formation of anatase is suggested. The addition of titanium in the system accelerates carbothermic reduction at 1873K, which have been finished at 0.5-1.5ks. The TEM micrographs of the powders indicate the aggregated grains consisting of the SiC and TiC crystallites (50-100nm in crystallite diameters). The size and morphology of TiC crystallites are almost the same as those of SiC in appearance. In the 0.4Ti powder, however, number of elliptic SiC crystallites possessing the disordered lamella patterns decrease. Thus the XRD lines of SiC are sharpened and are separated out from those of TiC. The SiO₂-TiO₂ liquid phase formation during the heat treatment at 1873K is suggested to play an important role in the carbothermic reduction process which yields the SiC-TiC powders.

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Woody ceramic, which is light in weight and thermally insulating, has been newly developed by baking Tobe kaolin mixed with vacant microcapsules. Woody ceramic is convenient for handling because of the weight reduction of about 30% compared with traditional Tobe ceramic. The dielectric constant ε′ and dielectric loss ε″ were measured in order to show that woody ceramic is an excellent tableware material to be used in a microwave oven. ε″ of woody ceramic at 2.45 GHz is smaller by about 20-30% than that of traditional Tobe ceramic. Woody ceramic is found to have ε″ appropriate for use as a tableware material to be used in a microwave oven.

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Ba(Ti_1-xZr_x)O₃ thin films have been synthesized on the titanium substrates at 160°C by hydrothermal method. The surface roughness (R_a) of the film was 0.096μm. The molar ratio of Zr/Ti of the film analyzed by EDS was 0.25/0.75. The film microstructure depended strongly on both starting materials and KOH concentration. The grain size became larger from approximately 0.6 to 1μm with increasing KOH concentration from 1×10^-3 to 3.5×10^-3mol·m^-3 at am aqueous solution of 7.8×10^-5mol·m^-3. The Ba(Ti_0.75Zr_0.25)O₃ thin film synthesized in an aqueous solution of 7.8×10^-5mol·m^-3 containing 3.5×10^-3mol·m^-3 KOH showed a dielectric constant of about 426 and dielectric loss of about 0.077 at 1kHz. The transition point between the ferroelectric and paraelectric phases of the film heat-treated at 300°C for 0.5h was approximately 10°C.

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Strength development and microstructures were investigated for a hardened mortar using eco-cement manufactured by replacing a part of the raw materials with incineration ash of urban waste and a waste-derived aggregate of sintered sewage sludge. Back-scattered electron images and X-ray image maps showed that the porous zones of Ca(OH)₂ usually observed at the interface between the normal Portland cement paste and aggregate did not form in mortars using the eco-cements. The hydration processes of eco-cements were discussed based on distribution maps of Cl, S, Mg, Na, K, Fe, Si, Al, Ca, and O.

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(1) A metastable phase relationship in the Al₂O₃-Cr₂O₃ system was made by investigating the existing phases in the samples obtained by heating the coprecipitated powders for 10h in the temperature range from 1000 to 1400°C (Fig. 1). There was a metastable two-phase region of AC+CC phases below about 1330°C.
(2) Equilibrium state of 1:1 composition at 1200°C was confirmed to be a single phase of the corundum solid solution.
(3) TiO₂ addition to the 1:1 composition was found to increase the reaction rate from the AC+CC phases into a single corundum phase at 1200°C.

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By rapid quenching of ZrW₂O₈ melt from 1300°C, dense specimens with few inner pores were successfully prepared. Dilatometry experiments were performed and an abrupt thermal expansion was observed in the range 120-160°C, probably due to removal of internal stress upon the first heating measurement from room temperature to 300°C. The specimen annealed at 200°C for removal of internal stress exhibited a negative average thermal expansion coefficient of -(4-5)×10^-6K^-1 from room temperature to 250°C, which was smaller than that of sintered ceramic ZrW₂O₈, (-(6-10)×10^-6K^-1). X-ray diffraction and secondary electron microscopy measurements revealed that the obtained specimen was a hybrid of ZrO₂ and/or WO₃ grains with -1μm diameter and ZrW₂O₈ grains with 10-25μm diameter. The smaller negative thermal expansion could be attributed to this hybridization due to decomposition of ZrW₂O₈ during the quenching process.

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Organosiloxane-based inorganic/organic hybrid films with high wettability toward engine oil have been prepared, aiming at the development of low friction materials under boundary and fluid lubrication conditions for application to automobile components. The presence of phenyl groups in organosiloxane-based hybrids was more effective for the high wettability with oil than other organic groups such as alkyl and fluoro-alkyl groups with different carbon-chain length. In order to readily obtain hybrid films without cracks, dimethyl groups were incorporated into the phenylsiloxane-based hybrid. The hybrid films were found to have the good wettability with oil up to the heat-treatment temperature of 400°C. In the C₆H₅Si(OC₂H₅)₃:(CH₃)₂Si(OC₂H₅)₂ ratios of 20:80 to 10:90, the hybrid films were found to keep a relatively good wettability with oil although the content of phenyl groups decreased.

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The effect of pores on elastic modulus, strength and fracture toughness of alumina ceramics was studied. Elastic modulus decreased with increasing porosity, and slightly increased with increasing pore size. On the other hand, strength decreased with increasing both porosity and pore size, being proportional to a reciprocal square root of the pore size. Fracture toughness decreased with increasing porosity and increased with increasing pore size. Fracture surface energy slightly increased with increasing pore size. The crack size at fracture origin were bigger 10 times or more than the maximum pore size, and increased with increasing pore size.

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c-axis oriented films of a layer-structured oxide in the [Ca₂CoO₃]_x[CoO₂] (CCO) system were prepared on MgO(100), SrTiO₃(100) substrates and MgO substrate with a Pt-buffer layer by pulsed laser deposition using on ArF excimer laser. In addition, the dependence of electrical resistivity of the c-axis oriented CCO thin films on MgO substrates on film thickness and their thermoelectric properties have been examined. c-axis oriented CCO thin films on MgO substrates had been fabricated by optimizing the deposition conditions, but they mainly tended to orient along the (204) plane of CCO, unless those on SrTiO₃ substrates and MgO substrates with Pt buffer which did not show a (204) plane of CCO. The CCO films on MgO (100) substrates had showed a dependence on film thickness of their measured resistivity below 300K. Measurement of thermoelectric properties showed that the resistivity along the ab-plane hardly varied with increasing temperature from 300 to 700K, while the Seebeck coefficient increased up to 150μV/K with increasing temperature.

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We prepared and characterized thin films of n- type oxide thermoelectric material Ca_3.4Al_1.2Co₂O_y (CACO) by rf magnetron sputtering method. We successfully obtained the good crystalline c-axis oriented CACO thin films on a SrTiO₃ (STO) (100) substrate. The electrical resistivity and the Seebeck coefficient of a CACO film with 1.4μm thickness were measured along the ab-plane in the temperature range from 300 to 900K. From an Arrhenius plot of resistivity values, we estimated that the activation energy of 0.33eV for the CACO films. The Seebeck coefficient of the film was about -60μVK^-1 at 370K. The conduction type was changed from n- to p-type with increasing temperature.

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A three-dimensional elastic analysis system for porous ceramics has been built. In this system, three-dimensional morphology of pores is modeled using voxel (volume pixel) elements from digital images. Elastic analysis with this image-based finite element model is performed by the homogenization method. In order to investigate this analysis system, the elastic properties and behavior of porous Al₂O₃ with spherical pores on the order of 1% by volume were computed. Young's moduli obtained by the homogenization method were consistent with both experimental and theoretical values. Using computed moduli of elasticity, the state of local stress concentration around the pores in a bending test was calculated together with the global stress in the sample. It was found that the dependence of the bending strength upon porosity can be described by taking into account local stresses around the pores. The combination of image-based modeling and homogenization method is a useful way to analyze the mechanical behavior of porous ceramics especially with inhomogeneous morphology.

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Simple binary alkali borate glasses containing sulfur were prepared by conventional melt quench method and chemical bonding states of sulfur were investigated by means of ultraviolet-visible (UV-VIS) spectroscopy, X-ray photoelectron spectroscopy (XPS) and ¹¹B MAS-NMR measurement. The glass samples were colored and colors changed with glass composition and alkali species. The blue coloration by absorption at around 585nm was explained with the formation of S₃^- anion spices. On the other hand, the glass samples colored in brown or red showed absorption spectrum around 450nm because of the formation of S_x^2- anion (polysulfide ion) speices. S2p binding energy was around 161eV, and this values was lower than that of orthorhombic crystalline sulfur. From these results, it was suggested that sulfur was present with a negative charge in R₂S-B₂O₃ glasses. In colored reddish brown regions, the formation of non-bridging oxygen from O1s spectrum in the glasses was noticed. Therefore, it is suggested that the formation of nonbridging oxygen in glasses largely effect the variation of sample coloration. The estimated fraction of fourcoordinated boron from ¹¹B MAS-NMR measurment was nearly equal to oxide glass systems. As a result, it is assumed that the effect of sulfur on the conversion of boron coordinate number is small because of a low solubility of sulfur in this glass system.

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Generally, it is difficult for 1.4μm band amplification to form population inversion between the initial ³H₄ and the terminal ³F₄ levels in Tm³⁺, because lifetime of the initial level is shorter than that of the terminal level. Accordingly emission properties and lifetimes of tellurite glasses co-doped with Tm³⁺ and various rare earth ions (Ho³⁺, Tb³⁺ and Eu³⁺) were investigated in order to improve the population inversion by co-doping method. These co-doped ions depopulated the terminal level rapidly by energy transfer from the terminal level to the co-doped ion. Especially, for the initial level, Ho³⁺ did not affect the population of the initial level because Ho³⁺ cannot easily cause cross-relaxation. Ho³⁺ had the largest effect on lifetime of the terminal level without decreasing the population of the initial level. Ho³⁺ showed the best performance among three investigated rare earth ions as a co-doped ion.

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In attempt to synthesize β-Al₂O₃ platelets using a novel method, powder mixtures consisting of γ-Al₂O₃ and NaF were heated in a platinum crucible. The effect of the mixing ratio of the raw materials, heating temperature and duration of heating at the selected temperature on the formation of the β-Al₂O₃ platelets was investigated. When powder mixtures consisting of γ-Al₂O₃:NaF=1:X (X=1-4; molar ratio) were heated at 900°C for 3h, β-Al₂O₃ hexagonal platelets formed. The size of the platelets were 3-8μm in diameter and 10-20 in aspect ratio, independent of the amount of NaF in the starting powders. When a powder mixture consisting of γ-Al₂O₃:NaF=1:2 was heated at 700 to 1100°C for 3h, β-Al₂O₃ platelets systematically formed. The size and morphology of the platelets were the same as above, independent of heating temperature. In addition, when the powder mixture consisting of γ-Al₂O₃:NaF=1:2 was heated at 800°C for 0h, β-Al₂O₃ platelets with the same size and morphology formed.

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Bi-layers consisting of porous La_0.6Sr_0.4Co_0.2Fe_0.8O_3-δ (LSCF) substrate and dense film of Ce_0.9Gd_0.1O_1.95 (CGO) have been successfully fabricated using slurry-coating process. A CGO powder dispersed in acetone was deposited onto a pre-sintered LSCF (containing 50 mass% CGO) substrate, and then co-fired such that the thin electrolyte was fully densified and the substrate remains highly porous. Co-fired CGO film was well bonded to the substrate; crack- and pinhole-free, and exhibited very low ohmic resistance. The NO decomposition properties of electrode-supported type electrochemical cell, LSCF (substrate) |CGO (film)| LSCF (screen-printed) were investigated. A strong correlation between the structure of the working electrode and the NO decomposition characteristics were observed. By using electrode-supported thin electrolyte, the required electric power for NO decomposition could be remarkably reduced.

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