Well-organized ZnO whiskers were grown on the sapphire single crystalline substrate with a relatively high growth rate using the chemical-vapor-deposition technique. The ZnO whiskers showed ultraviolet emission on the photoluminescence and cathodoluminescence spectra. The intensity of the ultraviolet emission was comparable to the blue emission obtained from the commercial blue phosphor.

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Multilayered Al₂O₃/3Y-TZP hybrid composites, in which multilayer and nanocomposite structure coexisted, were fabricated using nanocomposite techniques by which fine SiC particles are dispersed into both Al₂O₃ and/or 3Y-TZP layers. All composites were fabricated by stacking of greensheets that prepared by doctor blade method. Microstructural observation by scanning electron microscopy (SEM) confirmed that all multilayered composites were successfully fabricated without any defect and reaction phase. Residual stress measurement using X-ray diffraction (XRD) analysis revealed that residual stress could be controlled by dispersing nano-sized SiC. Upon analysis of crack propagation behavior of these composites, crack deflection was observed at layer boundaries between Al₂O₃ and 3Y-TZP layers; it is considered that the angles of deflection are strongly affected by the magnitude of residual stress.

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Crystallization behaviors in Ge-doped SiO₂ fiber preforms fabricated by vapor-phase axial deposition (VAD) method have been investigated. Since X-ray diffraction (XRD) peaks at around 2θ=22° in the crystallized glasses are reported to be strongly related with the induced second- and third-order optical nonlinear effects in poled glasses, enhancement of such crystalline phases is quite important and useful for fabrication of nonlinear functional glasses. It has been found that crystallization behaviors are drastically affected by thermal annealing and ultraviolet (UV) laser irradiation performed prior to heat-treatments for crystallization. In particular, it has been clarified that a crystalline phase, which is known to be highly effective for increase of induced optical nonlinearity, can be increased by pre-treatments of UV-laser irradiation at λ=193nm wavelength. These results suggest that modification of initial defect states in Ge-doped SiO₂ fiber preforms could lead to fabricate crystallized glasses with optical nonlinearity induced by poling and/or crystallization.

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The mineralogical compositions of bituminous fly ashes varied depending on the locations of hoppers attached to an electrostatic precipitator in coal-fired power plant. From the first hopper towards the third hopper, that is, as the particles of fly ashes decreased in size, the content of glassy phase increased, while the amount of α-quartz decreased. When the boiler was operated at full load in comparison with operating at half load, the content of glassy phase was greater. The chemical compositions of the glassy phase showed a tendency in Al₂O₃ increase, while SiO₂ decreased as the particles size became smaller.

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Mesoporous zirconia was prepared by the hydrolysis of zirconium tetrapropoxide (ZTP). Crystal structure of zirconia was controlled by using different hydrolysis procedures. A large amount of water and subsequent calcination led to the formation of mesoporous monoclinic zirconia with the pore size of 20 nm, while non-porous tetragonal zirconia was prepared with a small amount of water. Mesoporous tetragonal zirconia with controlled pore size was prepared from ZTP and carboxylic acids with different alkyl-chain length. The average pore size of the tetragonal zirconia increased from 4.8 to 7.5 nm with increasing alkyl-chain length of carboxylic acids. A complex of ZTP and carboxylic acid formed a hexagonal mesophase at the molar ratio of carboxylic acid to ZTP≥1.5. The lattice parameter of the hexagonal mesophase increased with increasing alkyl-chain length of carboxylic acid. The hexagonal mesophase, however, disappeared when the precursor melted over 58°C. The calcined zirconia consisted of the aggregates of crystallites, and the mesopores were located at interparticles. The appropriate coordination state and alkyl-chain length of carboxylic acid are probably effective in preparing mesoporous tetragonal zirconia and controlling the mesopores.

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A two-dimensional microstructure with low reflectance was fabricated on the surface of an SiO₂ plate by the precise regulation of its shape and surface morphology. A periodically dotted mask pattern of a positive resist was formed on SiO₂ by a two-beam interference method using a He-Cd laser with a wavelength of 325 nm. The substrate was rotated by 90° between the first and second irradiation steps. The microstructure of SiO₂ was etched using an electron cyclotron resonance plasma. The reflection loss was effectively minimized by overcoating an SiO₂ thin film on the microstructure followed by chemical etching in an HF solution. Steady fabrication of subwavelength structures (SWSs) having a reflectance less than 0.1% was possible by using these surface treatment methods.

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NH_x/OH surface groups of four different commercial silicon nitride powders produced by two different methods: diimide precipitation and carbothermal reduction with different nitriding media were determined by diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy. The results show that for both methods the nitriding media has a profound effect on the powders surface composition. In silicon nitride powders produced using NH₃ as nitriding media in both methods, surface hydrogen content in the form of NH_x/OH groups is larger than for a powder using N₂ in the carbothermal reduction process. The intensity of NH and NH₂ groups identified and quantified by DRIFT (this work) correlate with the amounts of N₂ desorbed molecules above 1300°C and NH₃ desorbed molecules below 1300°C, measured by temperature programmed desorption mass spectroscopy (TPDMS) for the same powders, respectively. It is concluded that the NH structures form part of the surface layer.

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The initial charge/discharge behavior of LiNi_0.5Mn_0.5O₂ for a Li-ion battery has been examined by XRD, in situ XAFS and electrochemical methods. The LiNi_0.5Mn_0.5O₂(R¯3 m:a=0.28999(7)nm, c=1.4330(7)nm in a hexagonal setting) was observed to retain its initial structure after charging to 4.5 V (vs. Li/Li⁺). XAFS measurements have also revealed that the majority of the nickel and manganese, respectively, exists in a divalent and a tetravalent state. Upon charging LiNi_0.5Mn_0.5O₂, Ni²⁺ ions were consequently oxidized to Ni⁴⁺. A Li-ion cell constructed with LiNi_0.5Mn_0.5O₂/graphite shows only a 15% capacity loss after 500 cycles at 60°C.

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Fiber reinforced ceramic composite setter was produced by Organic Flocculating Method. Its mechanical and thermal properties were studied. Air-quenching method, combined with theoretical analysis of thermal shock behavior, was employed to determine the bending strength drop of the composite setter and the critical temperature of composite setter with different fiber contents after thermal shock. Results from air-quenching method show that the drop of bending strength after suffered thermal shock becomes severe with increasing fiber content in the composite setter. Phase transformation to cristobalite within 200-300°C temperature range was accompanied by abnormal thermal expansion and it is considered to contribute to the low thermal shock resistance of composite setters with high fiber content.

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Behavior of bromine doping into carbon materials with different heat-treatment temperatures (HTT) from 1000 to 2800°C were investigated, together with the characteristics such as XRD patterns, Raman spectra and electric conductivities of the respective bromine residue compounds prepared by debromination of the doped samples. It was found that there are two different cases in the behavior of the carbon materials for bromine doping depending on their HTTs; one is the carbons with high HTT (HTT≥2000°C), the other those with low HTT (HTT≤1900°C). The carbons of high HTT group form intercalation compounds with compositions up to C₁₀Br, and considerable fractions, such as 13-25%, of the intercalated bromine remain in the interlayer space of graphite after the debromination process, thus forming the bromine residue compounds. On the other hand, the carbons of HTT≤1900°C, except for HTT1000, absorb only small amounts of bromine, which are almost completely expelled by the debromination process. They apparently do not form residue compounds with bromine. The carbon with HTT1000 was found to have an unique character: It absorbed an appreciable amount of bromine and the remaining fraction of the bromine after debromination was rather large, although the XRD pattern and the electric conductivity were unchanged. It is thus suggested that the remaining bromine may exist on the edge of the crystallites by forming weak bonding with carbon atoms.

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For analysing color of lime glaze containing 1 mass% or 8 mass% of Fe₂O₃, the spectral absorption coefficients were measured by a method based on Kubelka-Munk theory. The strong absorption considered as a tail of absorption in ultraviolet region was shown at the short wave length side on the glaze containing 1 mass% of Fe₂O₃. The coefficients of the absorption increased largely with increasing Al₂O₃ content in glaze. But the absorption coefficients were almost independent with SiO₂. The spectral absorption coefficients of 8 mass% Fe₂O₃ were similar to the tendency of the glaze with 1 mass% Fe₂O₃. From the results obtained in the present work, the correction of the traditional admitted explanation, the variation of apparent color in the iron glaze is entirely explained by the variation of absorption in visible region, should be neccessary. An influence of factors other than absorption should be investigated on the variation of color.

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Monolithic B₄C and B₄C-20 mol% CrB₂ composite ceramics were fabricated by hot pressing at 1900 and 2050°C. Erosive wear by Al₂O₃ particle impingement was tested using a sandblaster. The microstructure, mechanical properties and erosive wear of the ceramic specimens were examined and compared with those of a commercial B₄C ceramic. Monolithic B₄C and B₄C-CrB₂ composite specimens exhibited the high flexural strength of more than 600 MPa, which was attributed to their fine grained and uniform microstructure. Furthermore, a low erosive wear rate was obtained for these specimens compared with a commercial B₄C ceramic. In particular, the fracture toughness of the composite specimen hot-pressed at 1900°C was improved from 2.48 to 3.50 MPa·m^1/2 by the addition of CrB₂, and exhibited the highest resistance to erosion. Erosive wear occurred by the removal of the B₄C particles. The experimental results could be described by the equation V∝dE/K_C², as theoretically proposed by Ritter.

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Details of the microstructure were investigated in Fe₅Si₃-particles-dispersed Si₃N₄ ceramics, synthesized by reaction during sintering. The following results were obtained: 1) the size of most part of Fe₅Si₃ particles was around 2 μm, and those particles had plate-like and roundish form, 2) a linear crack was observed along the boundary between Fe₅Si₃ particles and matrix. The width of the crack was approximately 10-25 nm, and this value was close to a calculated value considering the difference in thermal expansion coefficient of the two phases, 3) at the boundary of Fe₅Si₃ particles and matrix, there existed a glassy phase of about 2 nm in width, Si, Al, Y, O elements being detected in this phase, 4) around the Fe₅Si₃ particles, a Si₂N₂O phase with irregular shape formed; in this phase ultrafine particles with 50-100 nm were incorporated.

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In the sol-gel synthesis process of barium titanate ultra-fine particles with using barium hydroxide aqueous solution and titanium alkoxide solution, the relationship between mixing condition of both solutions and the properties of particles was investigated. The static mixer was used as reactor and the mixing condition was quantitatively characterized by flow rate of solution in static mixer. Mean particle size and the width of size distribution of cubic-barium titanate ultra-fine particles were decreased with increasing flow rate, because the initial generated concentration of nucleation was increased by rapid mixture of solutions. Since the density of the hydroxyl group in a lattice of cubic barium titanate was increased with increasing flow rate, barium titanate had lattice structure of the expanded cubic perovskite.

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Effects of primary powders on PNN-PT-PZ piezoelectric thick films prepared by aerosol deposition method (ADM) have been studied. Powders clashed in strong impact occurred by collision between primary powder and substrate during the deposition were selectively deposited. Primary powders with high crystallinity were effective for producing thick films having high piezoelectric properties. The piezoelectric thick films in thickness of 38 μm formed by using PNN-PT-PZ piezoelectric ceramics powders with high crystallinity were annealed at 800°C for 1h, so that their piezoelectric constants (d₃₁) were-189 pm/V.

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Incineration ash of urban waste was heat-treated at 900°C with a foam water glass prepared from NaOH, NaF and Si. The treatment was found to suppress elution of hazardous heavy metals from the ash and simultaneously to decrease the dioxins in the ash. The fluorescence X-ray absorption fine structure (XAFS) measurement indicated that a trace amount of Cr (VI) in the fly ash transformed into a different valence upon treatment. Mortar specimens from the treated bottom ash showed satisfactory strengths and humidity-conditioning properties.

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Oxidation kinetics of hexagonal boron nitride powder in 8% O₂-20% H₂O/balance argon was investigated at 900-1100°C. Paralinear weight change curves were observed. The rate constant of BN oxidation in 8% O₂-20% H₂O/balance argon was almost the same as that in 20% H₂O/balance argon at the temperature below 1000°C, while at higher temperatures it was almost the same as that in 10% O₂/balance argon.

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