The oxygen storage capacity (OSC) of a ceria-zirconia(CeO₂-ZrO₂) solid solution containing 50 mol% ZrO₂ is approximately 400 μmol-O₂/g, which corresponds to approximately 50% of the theoretical OSC limit calculated from the valence change of the Ce ion. There are two possible explanations for the OSC suppression of approximately 50% of the theoretical OSC limit. The first mechanism is based on the thermodynamic reaction equilibrium; the second one is based on chemical kinetics. To clarify the reason for the suppression, the effect of the specific surface area of CeO₂-ZrO₂ solid solutions was estimated by measuring the OSC of CeO₂-ZrO₂ solid solutions with 3 levels of specific surface area. OSC was independent of the specific surface area of the CeO₂-ZrO₂ solid solutions in the composition range ≥60 mol% ZrO₂. The amount of bulk oxygen, which is released from inside the crystal lattice, could be estimated to be constant even though the specific surface area of the material changed in the composition range ≤50 mol% ZrO₂. Therefore, the mechanism of the OSC suppression was the thermodynamic equilibrium of the redox reaction of CeO₂-ZrO₂ solid solutions.

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The CeO₂-ZrO₂ solid solution is the most important oxygen storage/release material for use in automobile catalysts. In particular, the ceria-zirconia solid solution with a pyrochlore structure exhibits the highest oxygen storage capacity (OSC). In this study, CeO₂-ZrO₂ solid solutions containing Y₂O₃ were synthesized and their OSCs were measured to clarify the influence of an ordered arrangement of Ce and Zr ions on the OSC. As a result of this study, it is concluded that an ordered arrangement of Ce and Zr ions markedly improves the OSC of CeO₂-ZrO₂ solid solutions.

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Ternary alumino-silicate glasses, SiO₂-Al₂O₃-(MO, M₂O), contain two network former species, Si and Al. The glass structure basically consists of Si-O-Si and Si-O-Al linkages because of thermodynamically unfavorable of Al-O-Al linkage. However, Al-O-Al linkage is detected to exist as triclusters. Although some conditions have been proposed to explain the existence of the triclusters, it seems to be insufficient. This work attempts to clarify the conditions of the existence of triclusters in ternary alumino-silicate glasses based on the molar ratio of [MO, M₂O]/[Al₂O₃], [SiO₂]/[Al₂O₃] and the NBO (non-bridging oxygen) in the network. The existence of the triclusters conditions could be defined, stoichiometrically, as either [MO, M₂O]<[Al₂O₃] or 2[SiO₂]<3[Al₂O₃]+[MO, M₂O].

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Silicone was soaked in tetraisopropyltitanate (TiPT) at 30°C for various periods and then subsequently soaked in water at 25°C, an HCl solution at 25°C, an NH₃ solution at 25°C or hot water at 80°C for 24 d. It precipitated nano-sized anatase particles in it when it was soaked in hot water after soaking in TiPT, whereas it did not precipitate the anatase when soaked in any solution at 25°C after soaking in TiPT. The amount of the precipitated anatase increased with increasing period of soaking in TiPT before hot water treatment. The silicone in which anatase was precipitated formed apatite on it in a simulated body fluid (SBF) within seven days. The amount of the precipitated apatite increased with increasing amount of the precipitated anatase. The silicone precipitated with anatase is expected to form apatite on its surface even in the living body and bond to living bone through the apatite. The tensile strength and strain to failure of the silicone decreased by soaking in TiPT and subsequently soaking in hot water, whereas their Young's modulus increased.

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Silica coatings have been prepared by the spin-coating technique with the 172 nm vacuum ultraviolet (VUV) irradiation using a Xe₂^∗ excimer lamp. Perhydropolysilazane was used as a precursor. The chemical states, composition and optical transmittance of VUV-irradiated films were investigated by Fourier transform infrared, X-ray photoelectron, UV-visible absorption spectroscopies. The results showed that VUV irradiation was effective to remove hydrogen and nitrogen from the coating film and to incorporate oxygen to the film, so that the film transforms into silica. The effects of VUV treatment on the film were found to be dependent on oxygen concentration in surrounding gas. It was suggested that the effect of oxidation reaction due to active oxygen species and/or ozone is larger than that of the cleavage of a chemical bonding by photon energy.

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The effect of the addition of yttria was investigated on the preparation of titanium nitride aqueous slurry by ball-milling. Slip casting was carried out using the prepared slurries, and the effect of the slurry characteristics on forming and sintering behavior was studied. The amount of the dispersant to minimize the viscosity of the slurry increased with increasing both amount of yttria and milling time. A high density compact with homogeneously dispersed yttria could be prepared by slip casting the slurry prepared by long time milling. Titanium nitride sintered body could also be successfully prepared by firing in nitrogen atmosphere.

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A method for the quantitative determination of barium (Ba), magnesium (Mg), aluminium (Al), and europium (Eu) in the blue phosphor for fluorescent lamps was investigated by means of an alkaline fusion method, followed by inductively coupled plasma atomic emission spectrometry (ICP-AES). About 200 mg of samples were weighed in the Pt crucibles, 3.0 g of sodium carbonate (Na₂CO₃) and 1.0 g of sodium tetraborate (Na₂B₄O₇•10H₂O) added, followed by the fusion. After cooling, 10-20 ml of water and 20 ml of hydrochloric acid (1 : 1) was added. The contents heated on the hot plate were dissolved. After cooling, the solutions were adjusted with water to 250 ml. Ten milliliters aliquot of solutions were diluted with water to 100 ml, sample solutions measured by ICP-AES. Working standard solutions were prepared by addition the amount of Na₂CO₃, Na₂B₄O₇•10H₂O and hydrochloric acid (1 : 1) as same as sample. The four calibration curves obtained from the emission intensities were linear with high correlation coefficient of more than 0.999, respectively, and a good relative standard deviations (RSD, %) of 0.69(Ba15 μg ml^-1), 0.66(Mg5.0 μg ml^-1), 0.84(Al30 μg ml^-1), and 0.47(Eu1.0 μg ml^-1). This method was successfully applied to the determination of four elements in the experimental samples.

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Tantalum and niobium containing silicon oxycarbide ceramics were prepared from hybrid gels through cohydrolysis with methyltriethoxysilane and pentaethoxyniobium/tantalum, and pyrolysis at 1000°C. To investigate the behavior of free carbon in Si-Nb-C-O and Si-Ta-C-O ceramics, Raman spectroscopy was used. The spectra obtained before oxidation showed a higher shift of the G band at around approximately 1610 cm^-1, which means a cumulative band of G and D′. After oxidation, however, a symmetric G band, the shift toward a normal position at 1580 cm^-1 and a weaker background were detected. These phenomena were found to strongly correlate with the oxidation of carbon reactive sites, i.e., those of radical and edge carbon species in tiny graphene layer of free carbon.

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In order to find a counterpart for reducing the frictional coefficient of Al₂O₃-ZrO₂-CeO₂ plasma-splayed film, the sliding properties in mixed and boundary lubricating conditions was investigated. It was found that combination of a CrN-coated cast iron pin and an Al₂O₃-ZrO₂-CeO₂ plasma sprayed plate provided the lowest frictional coefficient among several combinations chosen from practical materials. The coefficient of friction was much lower than that of the materials combination widely used for piston ring and cylinder liner. It was inferred that the combination of a pin made of hard materials with high density, a smooth surface such as CrN-coated cast iron and a porous plate can reduce the frictional coefficient because less sliding resistance is implemented and porosity retains oil.

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Colloidal crystal template films have been prepared on a Pt-sputtered Si substrate by a dip-coating method with suspensions containing 870 nm polymethylmethacrylate (PMMA) microspheres. The mostly-packed PMMA template films could be obtained from the ethanol-ultra pure water suspensions containing P123 as a surfactant. Macroporous Pt films could be fabricated successfully by electrolytic deposition of Pt on the PMMA template film and subsequent removal of PMMA by thermal treatment. The use of the thick template film prepared from a suspension containing higher PMMA concentration resulted in a thinner wall of Pt framework and destruction of pore structure during the firing process to remove the PMMA template. Similar phenomena were observed for Pt films prepared by non-electrolytic deposition of Pt on the PMMA film. In contrast, firm Pt porous structure with thicker framework was maintained after removal of PMMA when electrolytic deposition of Pt was conducted on a thin template film prepared from a suspension containing lower concentration.

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