The crystal structure of copper oxide superconductors and their related compounds is described in terms of three basic structural blocks. The main block is the perovskite (ACuO_3-δ), and the others are the rock salt block (AO) and the fluorite block (AO₂). The perovskite block has four types, full perovskite structure (ACuO₃) and three types of oxygen deficient perovskite structure of ACuO_2.5, ACuO₂ and ACuO_1+z⋅Ba₂YCu₃O_6+z consists of two types of perovskite blocks and the series of superconducting compounds such as La₂Ca_n-1Cu_nO_2n+2 and M_mA₂Ca_n-1Cu_nO_2n+m+2 (M=TI or Bi and A=Ba or Sr) consist of perovskite blocks and rock salt blocks. The copper oxide series such as (Pb, Cu)A₂(R, Ce)_nCu₂O_2n+5 and A₂(R, Ce)_nCu₃O_2n+4+z (R: rare earth element, A=Sr or Ba) consist of perovskite blocks, rock salt blocks and fluorite blocks. The electroneutrality condition in the crystal was taken into account. The characteristic charge for each structural block was calculated using an ionic model. In La₂CuO₄, the perovskite block [La³⁺Cu²⁺(O^2-)₃] has a negative charge and the rock salt block [La³⁺O^2-] a positive charge. Therefore, the negative perovskite block is considered to be a hole acceptor. On the other hand, in Nd₂CuO₄, the oxygen deficient perovskite block [Nd³⁺Cu²⁺(O^2-)₂] is positively charged and the fluorite block [Nd³⁺(O^2-)₂] is negatively charged. Consequently, the perovskite block readily accepts an electron. The rock salt block usually has a positive charge and works as a hole donor for the CuO₂ planes in the perovskite block. The fluorite block has usually a negative charge and so works as a hole acceptor. A variety of new layered copper oxides which may turn into new high-T_c superconductors can be designed by employing the basic principles of the present block model and taking into account the lattice constant matching and the electroneutrality condition between the blocks. Thus the block model provides a guiding principle for the preparation of new layered copper compounds.

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Beta-SiC specimens possessing 13% stacking fault density were annealed at various temperatures for various time periods in an Ar or a N₂ atmosphere, and the changes in microstructure and the annihilation of stacking faults were investigated. Stacking fault annihilation was found to occur parallel with the grain growth which is supposedly controlled by surface diffusion and/or vapor tansport. Lattice strain enhanced by the incorporation of nitrogen into the SiC lattice was considered to be the most important factor to suppress the mass transport rate.

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In order to investigate a possible difference in the adhesion behavior of glass on ceramic substances between silicate and borate glasses, the residual stress in the glass layer of the glass-ceramic layered specimens was measured by a birefringence method with changing temperature. The experimental results agreed with the calculation for silicate glass, but not for borate glass: the experimental stress for the specimens having a borate glass layer was about 30% lower than the calculated value. This discrepancy was attributed to the occurrence of possible plastic flow in borate glass by the existence of two-dimensional structural units.

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Injection molding of hydroxylapatite and TCP utilizing solid phase reaction method was studied. Rod like test pieces (φ6×501) were produced by the injection molding using two powder-binder compounds: (A) 6mol of calcium secondary phosphate (>98.0%), 4mol of calcium carbonate (>99.0%) and several organic binders; (B) 6mol of calcium secondary phosphate (>98.0%), 3mol calcium carbonate (>99.0%) and several organic binders. After the binder extraction process, the test pieces were heated up to 1000°-1300°C at rate of 100°C/h. When sintered at 1300°C, the sintered test piece (A) was found to consist of hydroxylapatite according to X-ray diffraction and FT-IR. On the other hand, the sintered test piece (B) was found to consist of α-TCP.

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In brittle materials, unstable crack-extension leads to direct fracture. Therefore, some techniques such as Xray scanning, Ultrasonic microscopy, Acoustic Emission (A. E.) method have been developed for detecting the position and size of defects. However, these techniques do not have enough high precision. We have analysed crack-size and crack-orientation distributions of fracture origins statistically and proposed an effective method for non-destructive inspection (N. D. I.). In this paper, joint probability density contour-lines of fracture-location in test pieces subjected to 3-point bending load are shown. Furthermore, “N. D. I. -line” calculated from the joint cumulative distribution function is presented. More effective “screening-diagram” derived from N. D. I. -line is also suggested.

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Porous insulation films of alumina used in color picture tube heaters for high definition displays have been made by electrophoretic deposition (electrodeposition) process. In this process, the formation of gels on electrodes and the electrophoresis of Al₂O₃ particles in the solution occur simultaneously. Electrodeposited gels, which are important to control the insulation film structure, were analysed by powder X-ray diffraction, differential thermal analysis, Fourier transformation photo acoustic spectroscopy (FT-IR-PAS), and some other techniques. The X-ray diffraction patterns showed that the electrodeposited gels are amorphous. FT-IR-PAS spectra indicated the presence of hydroxyl and nitrate anions. It is shown that the shape of the gel on an uneven electrode surface depends on the configurations of aluminum and magnesium ions in the electrodeposition solutions.

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Slow crack growth (SCG) of mullite was studied by a double cantilever beam (DCB) method. Two types of mullite were made from a high-purity mullite powder and sintered at 1650°C for dense-type specimens (porosity=2.9%), and at 1575°C for porous-type ones (porosity=20.6%). In the DCB testing, crack opening displacements (COD) and applied loads were stored in a computer for detailed analysis. Crack lengths, K values and crack velocities (V) were then calculated with the computer using the stored digital data. The relationship between the compliance and the crack length for this specimen geometry (4.5mm×15mm×60mm with a 20mm-long notch) was obtained using several specimens with different crack lengths. K_IC values of two types of mullite were estimated as 2.05MPa·m^1/2 (dense-type) and 1.4MPa·m^1/2 (porous-type). Mullite was tasted in the water, the air and the dry N₂ gas. Mullite showed stress corrosion cracking affected by H₂O. It was found that the plateau regions in K_I-V diagrams for two different types of mullite appeared in different velocity ranges. The velocity ranges of each types of mullite were 10^-4m/s for dense-type and 10^-3m/s for porous-type. This results could be explained by the diffusion of H₂O gas through continuous pores.

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To clarify the effect of microstructure on crack growth behavior in Si₃N₄ ceramics, fracture toughness and three-point bending tests have been carried out for pressureless sintered (PLS) and hot-pressed (HP) Si₃N₄ specimens. As to the hot-pressed Si₃N₄ ceramics, the specimens were cut out parallel (HP-TL) and perpendicular (HP-SL) to the hot-pressing direction respectively for studying the anisotropy of mechanical properties. Microstructures subsequent to crack growing were characterized on the fracture surface and in the process zone wake by optical and scanning electron microscopies. The anisotropy was discernible in fracture toughness and bending strength, but hardly in microhardness. The process zone wake was damaged more severely in the HP-TL specimen than in the HP-SL one. The X-ray diffraction line profiles and pole figure analyses showed a preferred orientation of the β-phase in hot-pressed Si₃N₄. The HP-TL specimen had a fracture toughness and a bending strength about 10 percent greater than the HP-SL specimen. Pulling-out of elongated grains was more frequently observed on the fracture surface of the PLS specimen. The results obtained were discussed in connection with the preferred orientation of elongated β-phase grains from the microstructural points of view.

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Isothermal sintering of Ba(Mg_1/3, Ta_2/3)O₃ and ZrO₂ doped with Y₂O₃ was studied at various heating rates. Rapid heating was much effective in promoting densification process of Ba (Mg_1/3, Ta_2/3)O₃. X-ray diffraction, SEM observation and BET measurement showed that the rapid heating stimulated effectively the sintering of secondary particles whereas the slow heating contributed only to that of primary particles. When specimens were rapidly heated to the sintering temperature, the surface area of specimens did not change during the process of temperature increase. This resulted in a large shrinkage at the sintering temperature. When the specimens were heated slowly to the sintering temperature, the surface area was significantly reduced before reaching the sintering temperature and the densification was retarded.

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Up to date, neither Certified Reference Materials (CRM) nor Standard Reference Materials (SRM) has been available for thermal diffusivity values in the range around 10^-2cm²/s, which would be useful to advanced ceramics research. Therefore, a round robin test of Pyroceram glass ceramics Corning 9606 for one of the SRMs has been arranged by the subcommittee C-14.91 in National Institute of Standards and Technology (NIST)/ASTM. The results of thermal diffusivity measurement of the Corning 9606 have been described toward the international collaboration to certify Standard Reference Material. The surface of a disc sample was coated by carbon spray. The apparent thermal diffusivity of an identical sample increased with the number of laser beam flashing because the irradiation of a laser beam burns the carbon coating: (1) a small low temperature rise caused by lower absorption ratio of damaged coating substance increases the apparent thermal diffusivity associated with the negative temperature dependence of thermal diifusivity of Corning 9606 and (2) a burned carbon coating permits the penetration of the laser beam to the sample, which caused fast temperature rise of back surface. For reducing the irradiation damage of carbon coating, a glass cell filled with a CuSO₄ solution was inserted in the laser beam path as a variable attenuator. Ninety percent attenuation for the sample 0.97mm thick was found to be favorable to determine the thermal diffusivity value with sufficient reproducibility. The effect of transparency of the sample on the measured thermal diffusivity was also estimated by the theoretical calculation and this clearly confirmed the usefulness of carbon coating. Based on these careful preliminary examinations, the thermal diffusivity values of Corning 9606 in a temperature range between room temperature and 976K were independently determined using two different apparatuses and good agreement was found.

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Cyclic fatigue behavior of sintered silicon nitride was investigated by the rotating bending test method. The fatigue data were analyzed using Weibull's statistical approach based on the power law crack growth relation. This analysis agreed with experimental results. The relation between the number of cycles to failure and the initial stress intensity factor calculated from the defect size measured by fractography was discussed. As a result, the fatigue failure was caused not only by the surface defects but also by the internal defects. The cyclic fatigue behavior of silicon nitride was explained by the K₁-V diagram, in which the cyclic stress corrosion cracking (SCC) mechanism and the cyclic fatigue crack growth mechanism independent on SCC were taken into consideration.

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The bending strength of commercial porcelains for tablewares from ten makers in Tono district, Gifiprefecture was investigated by using test bars of the same size, non-glazed or glazed and fired in respective makers. An unglazed porcelain body which showed the maximum mean bending strength of 8.9kg/mm₂ had a maximum relative density of 97.5% with pore size less than 20μm. The bending strength of unglazed bodies was in the range from 4.9 to 8.9kg/mm₂ and was increased to the range from 7.0 to 12.0kg/mm₂ by glazing. In general, when the compressive stress in glaze was over 2.0kg/mm₂, fracture occurred from the origin in the bodies and the glazing increased the bending strength of porcelain bodies by about 3.5kg/mm₂. Especially, pores at the boundaries between glaze and body generated during firing acted as fracture origins and reduced the bending strength.

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Structural change in the plasma-sprayed alumina coatings by laser melting was investigated. Three layers were observed in the cross-section of laser-treated coatings, melted, heat-affected and as-sprayed zones. X-ray diffraction analysis revealed that both the melted and the heat-affected zones. X-ray diffraction analysis revealed that both the melted and the heat-affected zones were entirely alpha-alumina, while the assprayed zone consisted of mainly gamma-alumina. The melted zone, a portion apparently melted by laser with subsequent solidification, had a columnar structure with less porosity but with many cracks. The heataffected zone is probably a portion which did not melt but underwent the phase-transformation from gamma to alpha phase by laser heating. The relationship between the coating structure and laser parameters, such as power and beam traverse speed, was also investigated by one-pass treatment under various conditions. When treated under the conditions such that the beam speed is proportional to the laser power, the size of the heat-affected zone increased with the increase both in beam speed and laser power. This indicates that the size of the heat-affected zone depends on the energy density rather than the total energy input. Experiments under various beam traverse speeds revealed that the grain size in the melted zone was inversely proportional to the square root of the beam traverse speed.

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Preparation conditions of ZrN fine powders from ZrO₂ by the thermite method using Mg under a nitrogen flow (200cm³/min) have been investigated. Operation conditions for acid washing and the electrophoretic deposition of ZrN to obtain well defined ZrN powders have also been studied. The Mg/ZrO₂ molar ratio was kept constant at 5 but the charge varied from 1 to 7g. No unreacted ZrO₂ was observed in the products. ZrN fine powders of single phase have been synthesized at 600°-800°C in a relatively short time. On the other hand, about 0.5-0.8wt% of Mg remained at the ZrN particles after acid washing with 1-2M HNO₃. The amount of Mg was not affected by synthetic temperature. It was found that the electrophoretic deposition method is a convenient and effective means for the recovery of ZrN fins powders from the products suspended in ethanol after acid washing.

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The mechanism of curing of polycarbosilane (PCS) fiber has been investigated. Polycarbosilane has been melt-spun to fibers in the diameter range of 21-113μm. The rate of curing of PCS fiber was measured with a thermo-balance in Ar-O₂ gas mixtures with 5-100kPa O₂ at temperatures from 413K to 463K. The rate of curing increased with increasing curing temperature and p_O2, and with decreasing fiber diameter. The fiber melted to agglomerate in a mass, depending on the curing temperature, p_O2 in Ar-O₂ gas mixtures and the size of fibers. A cured layer, through which oxygen molecules can advance and reach the reaction interface, was formed around the fiber. The reaction interface receded towards the center of the fiber as the curing progressed. In the early stage of curing, the kinetics followed the contracting-disc formula: 1-(1-X)^1/2=κt. The apparent activation energy was 87.7kJ/mol. The rate constant κ was proportional to p_O2 and was inversely proportional to the diameter of the fiber. It is considered that the curing of PCS fiber is controlled by the interfacial reaction. In the late stage of the reaction, curing is controlled by the diffusion of oxygen through the reaction layer.

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Single crystal of lead zirconium titanate (PZT) were grown by slow cooling method from fluxes of PbO-KF-PbF₂ and PbO-KF-PbCl₂ system. (1) Single crystale of PZT with a size smaller than 1mm were gown from the flux of PbO-KF-PbCl₂ system. (2) Single crystale of PZT of a maximum size 1.7×1.7×0.9mm were grown from the flux of PbO-KF-PbCl₂ system. The obtained crystals were reddish brown in color and their composition was determined to be Pb(Zr_0.52Ti_0.48)O₃ by EDX.

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Mechanical and electrical properties of nano-composite ceramic materials composed of Al₂O₃ matrix and nano-meter size SiC particles are described. The composites including less than 5vol% SiC particles have the same order of resistivity and dielectricity as those of the non-SiC material, while keeping highly improved-mechanical properties. The incorporation of 5vol% SiC into Al₂O₃ matrix might be promising for materials used under harsh circumstances.

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Thin films of BaTiO₃ were prepared by CVD using barium β-diketonate chelate {Ba(C₁₁H₁₉O₂)₂} and titanium tetra-isopropoxide {Ti[OCH(CH₃)₂]₄} as precursors. BaTiO₃ films deposited from 700° to 1000°C on MgO (100) substrates showed prominent a-axis orientation. X-ray pole figure measurement by Schulz's reflected method indicated that the CVD-BaTiO₃ films deposited from 900° to 1000°C grew epitaxially on MgO (100) substrates. SEM observation showed that rectangular grains aligned two dimensionally in the plane of the films deposited at 1000°C.

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Microporous membranes of hexaaluminates (Ba- and La-Al₂O₃) showed heat resistance much higher than that of the conventional Al₂O₃ membrane. Although the Al₂O₃ membrane cracked by the heat treatment above 1000°C due to γ-α transformation. Ba- and La-Al₂O₃ membranes retained crack-free microstructure and exhibited excellent selective gas permeation after calcination up to 1000°C.

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