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Tensile-failure is investigated in a yttria-stabilzed tetragonal zirconia as a function of the initial grain size and strain rate. The following aspect is very similar to those obtained for superplastic alumina dispersed with ZrO2 or doped with MgO: microcracking that leads to failure is caused by the extensive coalescence of micrometer-sized cavities growing with deformation. Concerning this process, discussion will be given to the effects of the initial grain size and relative density.

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The simple approach with inexpensive production to synthesis SiC nanowires via Si ingot vapor-CH₄ gas system was performed in mullite tube furnace. The Si ingot was ground which was then sieved with a sieve No. 200 mesh (74 um) before used as precursor. The as-grown product was obtained in mullite boat after reaction at 1350^oC for 1 h. Characterization by a X-ray diffractometer, a field-emission scanning electron microscope and a transmission electron microscopy can confirmed that the product was SiC nanowires with typical diameter distributed in the range from 20-80 nm. The length of typical synthesized SiC nanowires were several hundreds of micrometers.

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It is well known that there are alpha and beta type in silicon nitride crystal structure. However, most of reports on synthesis of silicon nitride nanowire were related with alpha type, though beta-type is important in structural application due to higher thermal conductivity. In this work, beta silicon nitride nanowires were successfully synthesized by heat treatment of a homogeneous mixture of silica, carbon and a small amount of cobalt in nitrogen atmosphere.

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In this study, precursor for fibrous mullite powder was synthesized by simple alkoxide hydrolysis method, and the formation mechanism of fibrous mullite precursor was investigated. As-synthesized mullite precursor was amorphous, and showed fibrous shape consisting of nano-scaled amorphous particles. When the mullite precursor was heat-treated at 1300^oC, crystallization and grain growth of nano-scaled particles in mullite precursor proceeded, and fibrous polycrystalline mullite powder was formed. In the present synthesis process, fibrous precursor derived from aluminum isopropoxide acted as the template for fibrous mullite precursor.

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Organic-inorganic hybrid films containing organosilica nano-crystals have been obtained by an alcohol-free hydrolytic sol-gel process from a mono-functionalized organically modified alkoxide. Kinetically controlled self-organization has been used to design the hybrid nanocomposite films; nanocrystals of around 100 nm in diameter and 4 nm in thickness have been formed in transparent hybrid films. The layered nanocrystals have shown to be oriented within the films which exhibited an optical anisotropy (dn>10-3); the hybrid nanocomposite material has shown to be suitable for micro/nanofabrication by soft lithography and different patterned structured containing the hybrid nanocrystals have been obtained

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The water-soluble silicon compound (WSS), which was developed by our group, is a potentially new material suitable for synthesis of silicon containing ceramics by solution methods. WSS was utilized as a Si source to synthesize (Zn, Mn)₂SiO₄ bright green phosphor in combination with the parallel synthesis scheme using polymerizable complex method in order to establish the optimal manganese concentration quickly. The optimal manganese concentration in (Zn, Mn)₂SiO₄ phosphor giving rise to the highest emission intensity was found to be around 0.02.

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Now shortage of fossil fuel is concerned as a world wide issue. Photocatalytic water splitting has attracted much attention because of its potential for the direct production of H2 for clean energy. In the present study, we report synthesis and water-splitting property of pyrochlore structure Y2Ti2O7 photocatalyst by complex gelation method.

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In recent years, metal oxides which exhibit photocatalytic activity, such as TiO₂, attract attention. TiO₂ has several polymorphs, such as, anatase, rutile, and brookite. It is important to control the polymorph of TiO₂ for its application as photocatalyst. Moreover, morphological control of TiO₂ is also important for application of TiO₂ in various fields. In this study, synthetic process of TiO₂ with controlled shape and polymorph was investigated. Water-soluble titanium complex was employed as precursor and deposited on the templates via layer-by-layer assembly. Hydrothermal treatment was carried out for crystallization of TiO₂.

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Brookite-type titanium dioxide with unique morphology could be obtained by hydrothermal treatment of titanium citrate complexes in the presence of excess amount of ammonium solution. With increasing ammonium concentration, brookite phase gradually appeared, while single phase anatase was synthesized without additional amount of ammonia. The aspect ratio of the obtained brookite particles increased with amount of added ammonia and ribbon-like agglomerates were produced at high ammonium concentration. The reason why the brookite with this unique morphology is obtained may be attributable to the character of titanium citrate complex itself, because the same type of particles could not be obtained using other titanium complexes.

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TiO2 is one of the most important industrial material, that has eight polymorphs under room temperature and ordinary pressure. In this study rutile-type TiO2, one of the polymorphs, are prepared by hydrothermal treatment of Ti-tartarate complex in the presence of large amount of H2O2. Prepared rutile was spherical shaped and mono-dispersed with size of about 10 nm. We report possible structure of Ti-tartarate complex with H2O2 and formation mechanism of nano-sized rutile from the complex under hydrothermal reaction.

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Our study group have reported metastable TiO2(B) had been synthesized by hydrothermal treatment from water-soluble titanium complex. Synthesized TiO2(B) had plate-like morphology and the particle size was about 40 nm. Therefore, synthesized TiO2(B) had very large specific surface area though the particles were agglomerated. W/O emulsion was made by water-soluble titanium complex was dispersed in organic solvent. The emulsion was very fine droplet. Hydrothermal treatment of W/O emulsion was tried to synthesize of TiO2(B) had large surface area and high dispersivility.

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ZnO has a wide band gap of 3.37eV at room temperature and has attracted some interest because it is considered a promising green light-emitting phosphor for low-voltage luminescence in flat panel displays such as vacuum fluorescent tube (VFDs) and field emission displays (FEDs).It has been increasingly requested to develop blue cathode phosphors with high-efficiency and low-cost. The blue emission luminescence can be expected in Mg-doped ZnO because the band gap increases under partial substitution of MgO for ZnO. In the present work, the fabrication for (Zn,Mg) O solid solution and the effect of Mg-doping on the photoluminescence were investigated.

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Millimeter-wave heating is expected as an environmentally-friendly heating technology. On the other hand, SiAlON phosphor has received much attention as one of LED materials, recently. In this report, Eu-Doped 􀁅-SiAlON which emits strong green light under UV or blue excitation were synthesized using Millimeter-wave heating technology. For comparison, the experiments using conventional heating were carried out under the same conditions. Phase identification for the samples was performed by X-ray diffraction analysis. Photoluminescence spectra of the powders were also measured using a fluorescent spectrophotometer.

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We report on dielectric properties of nanostructured barium titanate free-standing films with an average grain size from 57nm to 1600nm prepared at the liquid surface by sol-gel method using high concentration Ba-Ti alkoxide precursor solutions. Free-standing films with a coarse grain showed a normal ferroelectric behavior. Free-standing film with a grain size of 57nm, however, showed unusual frequency dependence of dielectric response and polarization reversal characteristics.

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