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Transparent aqueous solutions of colloidal layered titanate, niobate, tantalate, vanadate, tungstate and molybdate nanocrystals were synthesized by a simple and convenient solution process at room temperature. When colloidal titanate and niobate nanocrystals were synthesized by mixing the corresponding metal alkoxide, amines and water, amines with strong basicity provided transparent colloidal solutions. This suggested that the acid-base reaction between metallic acids and the used alkylammonium hydroxide or alkylamines played an important role in the synthesis of the transparent aqueous colloidal solutions.

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Microwave processing is expected to be suitable for the synthesis of materials with non-equilibrium structure in nano- or mesoscopic scale. Homologous compounds, Fe2O3(ZnO)m, with the natural superlattice structure were obtained within a short period by solid state reaction of component oxides under microwave irradiation. TEM observation revealed that two types of superlattice structures were observed in different Fe concentration. In addition, we have successfully observed a formation of nano-scaled modulated lamellar structure induced by spinodal decomposition. It is conclude that the non-equilibrium nature of microwave selective heating, as well as rapid heating and quenching effects, plays a key role to form the superstructure.

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High-concentration niobium (V)-doped TiO2 nanoparticles of the non-equilibrium chemical composition have been synthesized via Ar/O2 radio-frequency thermal plasma oxidation of mist precursor solutions, with various Nb5+ concentrations (Nb/(Ti+Nb)=0–0.25.0). The solubility as high as ~25.0 at.% has not been achieved before by wet-chemical techniques. The preferable anatase formation was attained in the plasma-synthesized powders, and was enhanced by the niobium doping. The transformation from anatase to rutile was effectively inhibited with increasing the Nb5+ content.

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Silica-Alumina mixed oxides with Si-O-Al bonds show a high brønsted acidity since protons (H+) are introduced as Si-OH-Al due to the charge compensation of Si4+ and Al3+. In order to obtain high proton conductivity, it is important that Si and Al atoms are alternately arranged. In this study, we focused an acid-base reaction to obtain highly dispersed Si-OH-Al bonds. AlCl3 and Si(OC2H5)4 or Si(OCH3)4 were used as acidic and basic raw materials, respectively. Gas chromatography-mass spectrometry (GC-MS) measurements revealed that C2H5Cl gas was formed after mixing AlCl3 and Si(OC2H5)4, suggesting the formation of alternate Si-O-Al bonds. On the other hand, a by-product of C2H5OC2H5 was also obtained at room temperature. Molecular simulation (gaussian09) results suggested both Si-O-Al and Si-O-Si bonds were formed at room temperature. The obtained mixed oxides were characterized by XRD, 27Al-MAS-NMR and FT-IR.

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Bronze type TiO2 was prepared by hydrothermal method from glycolato titanium complex aqueous solution. Bronze type TiO2 suspension was applied to glass substrate and heated at 673 and 773 K for 1h. The bronze type TiO2 thin film showed high photo-induced hydrophilicity as much as anatase type TiO2 thin film. On the other hand, The hydrophilic property of bronze type TiO2 in the dark was higher than that of anatase.

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Hydrothermal synthesis and morphological control of brookite-type titanium dioxide were performed using an aqueous solution of a water-soluble peroxo-glycolato titanium complex in the presence of various amines. Single phase brookite-type TiO₂ could be obtained using amine as an additive. The aspect ratio of the obtained brookite particles was approximately 1 using dimethylamine or trimethylamine. The brookite particles had many crystal facets and were polyhedron shaped. The reason for the formation of brookite with this polyhedral morphology may be attributed to an interaction between a negative charge of TiO₂ surface and amine cation.

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The liquid phase process for synthesis of inorganic materials has attracted much attention since it is an environmentally-friendly process. Water-soluble complexes have been developed as key precursors for aqueous phase synthesis of oxide materials. In this study, morphological control of titanate materials has been achieved by using organic additives. SrTiO₃ nanocubes were prepared from water-soluble Ti complex , oleic acid, and hydrazine by hydrothermal process. TiO₂ hollow capsules were prepared using polystyrene spheres as template. Water-soluble Ti complexes were deposited on templates by layer-by-layer assembly. After removal of templates, hydrothermal treatment was carried out for crystallization of TiO₂.

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Various F^- scavenger was applied to the equilibrium reaction of metal fluorocomplex for LPD reaction process. Free F^- Comcentration decreased with the reaction time for more than 40 hours and depended on the equilibrium constant. TiO₂ thin film was deposited using Fe(NO₃)₃ solution as the F^- scavenger. Composition of deposited films depends on the Fe(NO₃)₃ and anatase and FeOF were obtained.

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The synthesis of aqueous solutions of colloidal layered tungstate nanocrystals was examined by reacting H₂WO₄ and alkylamines at room temperature. The use of alkylamines with short alkyl groups resulted in transparent colloidal solutions, whereas alkylamines with long alkyl groups provided the formation of precipitates. This suggested that the hydrophilicity of the amines played an important role in the formation of tungstate colloidal aqueous solutions. Moreover, WO₃ thin films were fabricated by the sol-gel method using the tungstate colloidal solutions. The WO₃ thin films had a high orientation, which may derive from the layered structure of the tungstate colloids.

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Manganese dioxide thin films were deposited on conductive glass slides from aqueous solutions using cetyltrimethylammonium chloride as a template. Gamma-MnO₂ thin films with lamellar structure with a 3nm layer distance were obtained when CTAC was used. The films were characterized for electrochemical behavior by cyclic voltammetry in a sodium sulfate solution. The lamellar-structured thin film, after being calcined at 373K, gave a high current response. this thin film may be a potential candidate of the active material in redox capacitors.

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We developed transparent ceramic Pr:LuAG scintillator for the positron emission tomography (PET) application. Up to now, single crystal Pr:LuAG scintillator is available and onboard the positron emission mammography (PEM). However, due to a huge segregation of Pr3+ ions, in single crystal fabricated by the melt growth, we cannot dope Pr3+ ions more than 0.2-0.25 mol%. By the vacuum sintering, we successfully dope 0.25-1 mol% Pr3+ into LuAG and the absolute light yield of Pr:LuAG ceramic exceed that of the single crystalline counterpart.

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A research to eliminate scattering losses completely in ceramics was successful in 1995, and also powerful laser generation with high beam quality was also achieved using transparent ceramics. It is not anymore true that the optical quality of ceramics is very poor, and probably ceramics will open a new era of optics in the future. Applications of opto-ceramics in laser, lens, and scintillator etc. have already been started and, nowadays the research and development on the ceramic laser has become worldwide.

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We report the transmission properties of transluscent polycrystalline alumina with respect to crystallinite alignment of alumina grains.

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Thiogallate compounds have a special feature that they exhibit no concentration quenching under heavily europium-doped condition. In this presentation, the synthesis, optical properties and application of these compounds will be introduced comprehensively.

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In this study, Mg doped ZnO particles were prepared using a solution technique. When 12 mol % of Mg (as a row material: MgCl2) was added to the solution of ZnCl2, the XRD pattern of the synthesized particles corresponded to ZnO thin filim after drying and heating at 1173 K. Since the diffraction peaks of MgO were not detected in the obtained ZnO film, 12 mass % of Mg seemed to be perfectly solved in ZnO. Farther, then thickness of the synthesized ZnO films showed micron size.

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