Novel machineable glass-ceramic consisting of crystalline β-Ca₂P₂O₇ and CaTi₄(PO₄)₆ phases, which three-dimensionally interlock with each other, was prepared by the controlled crystallization of the 2Na₂O⋅43CaO⋅25TiO₂⋅30P₂O₅ glass. The glass-ceramic prepared by reheating the base glass at 900°C was found to show good machineability with almost no chipping.

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Approaching to defect chemistry of electronic perovskite ceramics using high-resolution transmission electron microscopy and first-principles (ab-initio) pseudopotential total energy calculations effectively clarified new type of defect structures and its special features.
(1) In A-site-excess (Sr, Ca)TiO₃, bulk-ceramics, RP faults formation and preferential Ca-occupation of cation sites in the rocksalt structure of RP faults can be theoretically predicted. And the selective site occupation elucidates the empirical results, such as drastic changes of dielectric properties without contradiction.
(2) Dislocation loops with Burgers vectors of type 1/2 ‹100› were observed in non-stoichiometric and stoichiometric chemical composition alkaline earth perovskite ceramics. The dislocation loops appeared in A-site-excess and stoichiometric (Ba, Ca) TiO₃ sample entirely disappeared by electron beam irradiation, may be due to the Ca ion selective site occupation and promoting diffusion of ions into the perovskite structure, while the loops in B-site-excess and stoichiometric sample transformed into a crystallographic shear structure with a 1/2 ‹100› shear vector during electron beam irradiation.
(3) Peculiar planar defect structures never have been reported were observed and characterized in nonstoichiometric SrTiO₃ and BaTiO₃ thin films epitaxially grown on SrTiO₃ single crystal by a low-temperature deposition process, can be interpreted as metastable defect structures originating from the thermodynamically non-equilibrium growth conditions.

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In artificial bones, a steady bioactivity over long-term service, no dissolution of harmful ions and a sufficient mechanical strength are required, though the relative importance of the above factors depends upon the implantation place. In general, bioactive materials have no sufficient mechanical strength and, on the other hand, materials with high mechanical strength are not bioactive. In the present study, a porcelain enamel technique was applied to produce a hybrid material whose both bioactivity and high mechanical strength, which merely consists of inorganic materials. High-strength alumina and bioactive glass-ceramics were used as substrate and coating material, respectively, and an adhesion-glass was employed to achieve a tight bond between alumina and the bioactive glass-ceramic. Appropriate heat-treatments of the alumina, adhesion-glass and bioactive glass-ceramic composite resulted in the successful production of a hybrid material that has about 2.5 times stronger in bending-strength than that of an apatite precipitation-type glass-ceramic. This technique gives a useful process on production of ceramic-ceramic hybrid materials with high mechanical strength and bioactivity for bone substitution.

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The effect of chlorine on the sintering on Y₂O₃-doped zirconia has been investigated. Chlorine influenced the sintering in vacuum, but not in air. Only 100ppm of Cl was found effective. In vacuum, the shrinkage of the samples containing chlorine was delayed with pore growth above 1300°C. This phenomenon did not appear in the case of MgO-doped zirconia.

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Silicon carbide ceramic filters consisting of highly porous support and filtration layer were fabricated by cold isostatic pressing. The porosities of the supports were varied near the percolation threshold, 28.7, 33.7 and 35.8%. The silicon carbide layer with a finer pore size was coated on the supports to collect dust particles. The pressure drop (ΔP) was measured at various face velocities, dust loadings, and operation times. The separation efficiency was calculated by measuring the dust concentrations at the inlet and outlet of the filter vessel, and the cleaning efficiency was calculated by comparing the pressure drops before and after back-pulse cleaning. The results indicate that higher porosity of the filter support is favorable for preventing an increase of pressure drop and for improving cleaning efficiency. As the porosity in the silicon carbide filter support increased from 28.7% to 35.8%, the pressure drop decreased by as much as 30%. Most of dust particles were collected by the finer pores in the coating layer with efficiencies >99.9%. Additionally, better cleaning efficiency was obtained at higher porosity. The values of flexural strengths of the filter supports were over 20MPa even though a lower value was found at high porosity.

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Alumina-zirconia-graphite (AZG) materials are important refractories for AISI 304 stainless steel strip casting, which is especially used as slide gates and nozzles. AZG refractories were obtained through a baking technique using fused Al₂O₃, partially stabilized ZrO₂ and flake graphite as starting materials with Al, Si, and SiC powders as additives. A particle size distribution was according to the Furnas model for coarse Al₂O₃ (500-1000μm/medium Al₂O₃ (61-125μm/fine Al₂O₃ (<44μm in which the contents of coarse, medium and fine Al₂O₃ powders were varied with the constant amount of other fine particles in the matrix. The bulk density reached the values 3.29, 3.19 and 3.13g·cm^-3 when baked at 200°C for 2, 2 and 2.5h, respectively. The apparent porosity decreased from 7.6 to 6.3% upon increasing the baking time at 160°C from 0.5 to 2.5h, and then gradually increased from 6.3 to 6.6% as the baking time increased from 2.5 to 3.0h. The modulus of rupture was <80MPa when the baking time was 1.5h for all samples formed at 150MPa and baked at 200°C. On the other hand, the modulus of rupture increased sharply and attained a maximum value >120MPa for a baking time of 3.0h. The erosion fraction (E_r) increased with increasing apparent porosity (P_o) and could be expressed E_r=0.30P_o-0.27.

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Knoop hardness and the shrinkage behavior of Knoop indentation were investigated for zinc tellurite glasses. A minimum in Knoop hardness was observed at around the composition of 20ZnO⋅80TeO₂. This anomalous compositional dependence originated from a decrease in coordination number of both Te and Zn with increasing in ZnO content. The decrease of four-coordinated Te results in the breakage of Te-O network. In turn, the increase of ZnO₄ tetrahedra leads to the increase in covalent bonding character of the glass network. It is considered that these two effects cause the minimum of Knoop hardness. On the other hand, shrinkage of Knoop indentation in zinc tellurite glasses was observed only for the compositional range >20mol% ZnO. Considering the shrinkage of Knoop indentation as the result of a densification recovery in the glass, this compositional dependence suggests that ZnO₄ tetrahedra in this glass system remarkably contribute to densification under the sharp indenter.

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Crystallization behavior of α-AgI from melts and glasses in the system AgI-Ag₂O-B₂O₃ (Ag₂O/B₂O₃=3) was investigated by means of X-ray diffraction and field emission type scanning electron microscopy. Microcrystals of α-AgI were formed by rapid quenching of melts with 80mol% AgI and also by heating of the glasses with the largest amount (78mol%) of AgI in the glass-forming region. The crystallization process of α-AgI from rapid quenching of melts and heating of glasses was very similar to each other and is summarized as follows: (1) AgI-rich amorphous particles with 40-100nm in diameter dispersively formed, (2) amorphous particles were aggregated, and (3) α-AgI microcrystals with 20-30nm in diameter crystallized within the aggregates.

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Silicon nitride ceramics, with Y₂O₃, Al₂O₃ and MgO as sintering aids, have been sintered in a 28GHz microwave applicator using a number of sample insulation techniques. The sintering characteristics in terms of densification, α→β transformation, microstructural development and power requirement were studied and compared to identical samples sintered conventionally. All of the microwave sintered materials could be sintered to near theoretical density and a full α→β transformation obtained at temperatures around 200°C lower than the materials sintered conventionally. In addition, the microstructural development showed important differences, with the selective development of elongated β-grains being observed from the very early stage of transformation. Samples sintered using a powder bed insulation technique, achieved full α→β transformation at the lowest temperature, but a tendency to thermal runaway using this method of insulation meant the samples were susceptible to cracking. Samples sintered using silicon carbide plates as a low temperature microwave absorber reached full density and onset of transformation earlier than the other materials. In addition, the maximum power requirement for these samples was around 1/3 of that required for other insulation techniques, and more uniform heating meant that these samples were free from cracking.

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Epitaxial growth of yttria-stabilized zirconia (YSZ) thin films on Si (001) substrates containing SiO₂ layers of various thickness was in-situ monitored by reflection high-energy electron diffraction (RHEED). The inplane lattice parameter of YSZ at the initial stage of the deposition (the thickness of YSZ was below 5nm), was very close to that of the Si substrate when the thickness of SiO₂ was below 0.49nm. The in-plane lattice parameter of YSZ was significantly decreased approaching that of bulk YSZ when the thickness of YSZ was over 5nm. The relaxation of the lattice parameter was caused by the generation of misfit dislocations or regrowth of SiO₂ between the Si and YSZ interface. On the contrary, if the thickness of SiO₂ was between 0.68 and 1.1nm, the epitaxial growth was also confirmed, however, the in-plane lattice parameter did not change with the thickness of YSZ. The reason for the change of this lattice relaxation with the thickness of SiO₂ was discussed.

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The relation between cathode performance and thermodynamic stability of lithium manganese spinels, LiMn₂O₄, Li₂Mn₄O₉, Li₄Mn₅O₁₂, as cathode active materials for lithium secondary battery, has been investigated. The heat of dissolution of these samples was measured by the solution calorimetry method. The standard enthalpy of formation, Δ_fH⁰, the enthalpy change of reaction, ΔH, and the enthalpy change per mole of atoms for the formation reaction, ΔH_R, were calculated from the heat of dissolution. |ΔH_R| decreased in order of Li₄Mn₅O₁₂>Li₂Mn₄O₉>LiMn₂O₄, a larger |ΔH_R| meaning a thermodynamically more stable sample. In addition, lattice energies of these samples were calculated for a unit-cell. The trend order for lattice energies was the same as that for |ΔH_R|. A more thermodynamically stable sample makes a stable crystal structure and leads to a good cycle performance.

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LaCrO₃ has high conductivity and stability in reduced atmosphere. It is candidate material for separator in solid oxide fuel cells. It was difficult for Cr contained oxides to reach high density of sintered body. Some investigators had reported about the influence of Ti addition to improve sinterability of Cr-contained oxides. In this study, the influence of Ti substitution on sintering behavior of LaCrO₃ was investigated. Substitution of Ti to LaCrO₃ is effective to improve sinterability due to reduce particle growth by vapor transport. Activation energy for sintering of LaCr_0.8Ti_0.2O₃ is similar to that for La diffusion through the lattice. The diffusion of La is the controling process for sintering behavior of LaCrO₃.

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CVD diamond films were deposited on commercial WC cutting tools. An electron cyclotron resonance microwave plasma chemical vapor deposition (ECR-MPCVD) apparatus was used to deposit diamond films. Methane and hydrogen were used as gaseous source for CVD, and WC-Co (JIS standard: K-10) was used as a substrate for CVD. Cobalt on the surface of the WC cutting tool prevented CVD diamond from depositing on the WC cutting tool. Scratching with diamond particles on the surface of the WC cutting tool, which is one of the most popular pretreatments for enhancing the nuclei density of CVD diamond, was ineffective on the WC cutting tool without removing surface cobalt. On the other hand, Electrophoresis treatment was effective for increasing diamond nuclei density on the WC cutting tool without removing surface cobalt. However, CVD diamond films synthesized on the WC cutting tool (from which surface cobalt was removed) using electrophoresis pretreatment separated from the surface of the WC cutting tool. To improve the adhesion between CVD diamond film and WC cutting tool, heat treatment was performed after electrophoresis pretreatment. The heat treatment condition was 500°C for 1h in Ar flow. The heat treatment after electrophoresis treatment was effective for improving adhesion between WC surface and CVD diamond film. Vickers hardness test was carried out for estimating the adhesion. The Vickers hardness of the CVD diamond film obtained by the electrophoresis-heat pretreatment, was as hard as that of a CVD diamond film obtained with conventional scratching pretreatment. From the results of Vickers hardness test, it was found that heat treatment after electrophoresis process is effective for improving the strength of the adhesion layer.

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Bilayered SnO₂/TiO₂ thin films (SnO₂-overlayer/TiO₂-underlayer) have been prepared on a glass substrate by a spin-coating method using a solution of titanium alkoxide and tin alkoxide. Heating temperature of 500°C was adopted to convert TiO₂ and SnO₂ precursors into TiO₂ and SnO₂ polycrystalline films, respectively. The bilayer-type photocatalyst had a high transparency in the visible region and exhibited a very high photocatalytic activity for the decomposition of organic compounds in water under UV irradiation as compared with TiO₂ thin film. The SnO₂ surface of SnO₂/TiO₂ thin film also exhibited high hydrophilicity after UV irradiation as well as TiO₂ thin film.

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LaNiO₃(100)/CeO₂(100)/Si(100) as a metal/insulator/semiconductor heterostructure was prepared by a sol-gel method with a spin-coating technique. The structure of each oxide layer was investigated by out-of-plane and in-plane X-ray diffraction analyses. The high degree of {100} -orientation of the CeO₂ layers was obtained with higher heat treatment temperatures, 600-700°C. The in-plane measurements revealed that the CeO₂ layers had a nonepitaxial structure in spite of the deposition on the Si(100) substrates with good lattice compatibility. The LaNiO₃ layers on the CeO₂(100)/Si(100) also exhibited the preferential {100} -orientation without epitaxy. The crystallinity of the {100} -oriented grains in the LaNiO₃ layers was higher than that in the CeO₂ layers. The occurrence of the orientation was discussed in view of the interfacial energies at each interface.

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In order to deform titanium plates superplastically, a SiO₂-CaO mold has been developed. SiO₂-CaO particles were observed on the surface of plates pressed by this mold. The particles were transferred from the mold surface. For the examination of hydroxyapatite deposition ability, the titanium plates were immersed in simulated body fluid which had ion concentrations almost equal to those of human blood plasma. At the same time, titanium plates treated or untreated by NaOH were immersed in the simulated body fluid. After 1-4 weeks, hydroxyapatite layer deposited on the samples. Compared with untreated titanium plates, hydroxyapatite easily to deposited on titanium plates with SiO₂-CaO particles.

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