The structure of PbZn_1/3Nb_2/3O₃ ferroelectric relaxor was investigated by the single crystal X-ray diffraction and the extended X-ray absorption fine structure (EXAFS) techniques at room temperature. The crystal has a rhombohedral R3m symmetry with a=0.40620(4)nm and α=89.93 (1)°. The metal atoms are displaced from the cubic prototype positions by 0.035(1)nm for Pb, and 0.012(2)nm for Zn and Nb. The Pb atoms are statistically distributed at the 9b positions in the hexagonal setting. EXAFS analysis gave mean bond distances of 0.235(1)nm for Pb-O, 0.204(1)nm for Zn-O, and 0.194(1)nm for Nb-O. The coordination number of Pb was estimated to be 3.8 (2). Single crystal X-ray diffraction and EXAFS data suggested a pyramidal coordination for the local structure around Pb, which is similar to PbO₄ in PbO. The different bond distances of Zn-O and Nb-O imply a concurrent constriction of NbO₆ and expansion of ZnO₆ octahedra in the crystal, leading to an aperiodic distortion of the corner-shared octahedral network.

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Double-sided epitaxial YBa₂Cu₃O_7-δ (YBCO) films with different copper (Cu) contents were grown on (100) LaAlO₃ substrates using a hot-wall type metal organic chemical vapor deposition (MOCVD) apparatus. We investigated the relationship between Cu composition ratio of YBCO films and superconducting properties. Some precipitates were observed on the surface of the film and gradually became large as the Cu composition ratio increased. Despite the precipitation phenomenon, these YBCO films exhibited excellent superconducting properties at Cu composition ratios ranging from 2.5 to 4.0. The possibility of using the films for microwave application is also discussed.

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The mass change reaction of Si₃N₄ ceramics during sintering in a non-carbon-element furnace was investigated in a flowing N₂ gas environment as a function of the oxygen partial pressure, pO₂, in the range from 2.0×10^-4 to 3.0×10³Pa. There were four different pO₂ regions in the mass change reaction: passive oxidation, passive to active transition, active oxidation, and vaporization. It was concluded that the major reactions for the vaporization region are Si₃N₄(s)+3SiO₂(l)→6SiO(g)+2N₂(g) and Si₃N₄(s)→3Si(g)+2N₂(g).

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High-density 0.5PbNi_1/3Nb_2/3O₃⋅0.345PbTiO₃⋅0.155PbZrO₃ (0.5PNN⋅0.345PT⋅0.155PZ) ceramics were prepared by normal sintering with the addition of 0-3.66mol% MnO₂ and their piezoelectric and ferroelectric properties were investigated. The effect of MnO₂ addition on significantly lowering the value of tan δ in the range of 0.37 to 0.93mol% was proven. The lowest value (=0.37%) of tan δ was obtained in ceramics with 0.75mol% MnO₂. Electromechanical coupling factors, k_p and k₃₁, and the piezoelectric constant, d₃₁, decreased with increasing amount of MnO₂ addition. The highest values of k_p, k₃₁ and d₃₁ were 0.66, 0.38 and -362pC/N, respectively, and were obtained in the ceramics without MnO₂. The effect of MnO₂ addition on improving the value of the mechanical quality factor, Q_m, was proven in the range of 0.93 to 1.85mol% and the improvement was around twenty times that of the sample without MnO₂. The distortion in the shape of P-E hysteresis loops for samples with MnO₂ addition suggested that oxygen vacancies formed by substituting Mn³⁺ ions for B-site ions (e.g., Ti⁴⁺ and Zr⁴⁺ ions) in the perovskite structure partially inhibited the polarization reversal in the ferroelectrics. 0.5PNN⋅0.345PT⋅0.155PZ ceramics with 0.75-0.93mol% MnO₂ show great promise as practical materials for piezoelectric applications.

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In this study, a new microetching technique for the observation of ceramic surfaces by Penning discharge microsputtering is developed and applied to ceramic surfaces. Each ceramic surface was prepared by mechanical polishing and subsequent etching and the resultant surfaces were examined under both an optical and a scanning electron microscope. The results in the case of using with a gold target revealed high-definition images of the surface structure of the Si₃N₄, ZrO₂ and Al₂O₃-ZrO₂-Al₆Si₂O₁₃ ceramics after surface etching using this process. However, in the case of using a gold target, high-purity Al₂O₃ ceramics and Al₂O₃-ZrO₂ complex ceramics, the resultant surface preparation was unsuccessful. However, when using a titanium target, the procedure in both cases, was successful. This difference could be attributed to the difference in the effect of oxygen on both metals.

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For the development of a novel biodegradable membrane useful for surgical operations, the chemical interaction between β-tricalcium phosphate (TCP) and copolymerized poly-L-lactide (CPLA) in the TCP/CPLA composites was investigated by Fourier-transformed infrared spectroscopy (FT-IR) and dynamic mechanical analysis (DMA). From FT-IR measurements, chemical interaction between Ca²⁺ in TCP and O^δ- of ester C=O double bonds in CPLA was detected as the red shift of C=O stretching vibration mode. DMA measurements showed that the storage and loss elastic moduli of the composites increased with increasing in TCP content, corresponding to the strength change in Ca²⁺…O^δ-(=C^δ+) interaction, though glass-transition and softening temperatures did not change. The mechanical and thermoplastic properties of the composites were highly suitable for a guided-bone-regeneration membrane.

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Dense α-Si₃N₄ ceramics were fabricated by the tape casting technique using La₂O₃ as a sintering additive to effectively suppress the α-β transformation. Addition of a small amount of elongated β-Si₃N₄ seed particles significantly improved the toughness of sintered bodies from about 2 to 6MPa·m^1/2. It was found that both strength and toughness showed a linear dependence on the β-Si₃N₄ content, while hardness remained almost constant up to a β-content of 43%. Consequently, it was possible to fabricate the α/β-Si₃N₄ composites that showed much higher hardness (about 19GPa) than ordinary Si₃N₄ and SiAlON ceramics, as well as comparable strength (about 800MPa) and toughness (about 6Pa·m^1/2).

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A new synthetic route based on solution chemistry was developed for a compound semiconductor cadmium telluride (CdTe) via reduction of CdTeO₃ prepared by hydrolysis of the corresponding double metal alkoxide as a starting material. The CdTe double alkoxide solution was prepared by the reaction of cadmium acetate with Te alkoxide in the presence of Na alkoxide in ethanol. Amorphous CdTeO₃ was obtained by hydrolysis of the CdTe double alkoxide at room temperature and under the reflux conditions. Heat-treatment of the resulting amorphous CdTeO₃ powder at 400°C and 600°C in air resulted in transformation to cubic CdTeO₃ and monoclinic CdTeO₃, respectively. CdTe was obtained by heat-treatment of calcined amorphous and crystallized CdTeO₃ at 200-400°C in H₂. The products consisted of the primary particles of about 16nm in diameters and the Cd/Te ratios were chemically stoichiometric. A CdTe film was obtained from screen-printed amorphous CdTeO₃ paste on low-cost slide glass substrates by heat-treatment at 400°C in H₂.

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In order to increase homogeneity with a higher packing density of vibrocompaction fuel, we investigated the effect of size ratio and shape of multi-size powders on vibratory compacting, and the size segregation phenomenon which commonly occurs with vibratory compacting. Spherical glass beads and irregular glass particles were used in the present vibratory compacting. We propose a segregation model that expresses the relation between size segregation, size ratio and amplitude. Under the shaking condition of this study, our model well agreed with the experimental results. Before and after shaking, compacting behavior of the samples were observed by X-ray computed tomography (X-ray CT).

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Pulverization process of agglomerated Pd powder synthesized by wet chemical method was investigated. Pd slurry was prepared by mixing zirconia media and agglomerated Pd powder with normal hexane. And pulverization was conducted by pouring the Pd slurry on to slant board. Agglomerated Pd particles are loaded with shear force during flow on slant board and to be pulverized. The pulverization was evaluated by measurements of green density, surface roughness, shrinkage, and electrical resistivity of screen printed Pd electrode. And also pulverized Pd powder was subjected to SEM observation. The result indicated that the pulverization was strongly influenced by slurry flow length and a gradient of slant board which related to slurry flow rate.

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Structures of grain boundaries of SrTiO₃ semiconductive capacitor have not been fully elucidated. Several studies were focused on the SrTiO₃ systems which include additives, such as, Al₂O₃ or SiO₂. In this study, we first investigated the grain boundaries of Sr_0.975Ca_0.025TiNb_0.004O₃ which did not contain any additives. Then Bi₂O₃/CuO, which is a grain boundary modifier, was also added in order to investigate the process that changes grain boundaries into insulators. Samples heat-treated with Bi₂O₃/CuO were quenched in water and TEM (transmission electron microscopy) was carried out on these microstructures. Grain boundaries of samples sintered in a reduced atmosphere showed segregation of TiO₂ oxide phase, which included no traces of Sr. On the other hand, in grain boundaries of samples heat-treated with the Bi₂O₃/CuO agent, at least two phases existed. One phase included large amounts of Bi and Cu, while the other phase showed only traces of these elements. Near the grain boundaries Bi and Cu diffused into the matrix grains showing inhomogeneous diffusion of which diffusion lengths were different at each side of the grain boundary and seemingly lattice coincident with both grain boundary layers and matrix grains. In addition, steps of about 2nm in height were observed at grain boundaries.

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The applicability of a laser-speckle extensometer to the viscoelastic study of brittle materials at elevated temperatures is examined by the use of a soda-lime glass at various temperatures above the glass transition point for three different rates of tensile loading. The well-known thermorheological time-temperature superposition procedure in the observed stress vs. time curves successfully yields their master curve at the standard temperature. The shift factor a_T used for superposition and the stress relaxation function E(t), both of which are determined in this stress vs. time master curve, agree quite well with the results in literature. The potential capability of using laser-speckle techniques for a large-scale elongation, such as a superplastic elongation, is also addressed.

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Cubic Cs₂FeSi₅O₁₂ powder with the space group Ia-3d was synthesized by heating the powder mixture of Cs₂CO₃⋅2H₂O, Fe₃O₄ and amorphous SiO₂ with the molar ratio of Cs/Fe=2 and Si/Fe=5 at 1273K for 20h under Ar gas flow. The thermal expansion property of cubic Cs₂FeSi₅O₁₂ powder was investigated in the temperature range from 298 to 1273K using high-temperature X-ray diffraction. The thermal expansion rate of cubic Cs₂FeSi₅O₁₂ was lower than that of cubic CsFeSi₂O₆. Consequently, increasing the molar ratio of Si/Fe was effective for decreasing the thermal expansion rate of Cs-Fe-leucite compounds. Cubic Cs₂FeSi₅O₁₂ showed a lower thermal expansion with the mean linear thermal expansion coefficient of 1.75×10^-6K^-1 in the range from 573 to 1273K.

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Perovskite-type LnFeO₃ (Ln=La, Sm, Dy) powders were prepared by thermal decomposition of cyanidebridged heteronuclear complexes and their gas sensing properties to C₃H₆ were investigated. As a result, it was found that SmFeO₃ has the highest sensitivities to C₃H₆ among the perovskite oxides examined. By adding a small amount of Pd to SmFeO₃, gas-sensing properties such as gas sensitivity and response time were largely enhanced.

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Polycrystalline samples of LaRh₃B_x and LuRh₃B_x have been successfully synthesized by the arc melting method. Stoichiometric compositions of LaRh₃B and LuRh₃B have the perovskite-type cubic structure (space group Pm3m) and lattice parameter a=0.4251(1)nm and a=0.4126(1)nm, respectively. LaRh₃B has no nonstoichiometry of boron. On the other hand, perovskite-type LuRh₃B_x exists in the range of 0.3≤x≤1.000; the lattice parameter a of the perovskite-type cubic cell increases with increasing boron content x in the compound. The stoichiometric LaRh₃B and LuRh₃B have micro-Vickers hardness of 4.2 (±0.1) GPa and 7.7 (±0.5) GPa, respectively. The hardness of the LuRh₃B_x increases with increasing the B content.

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Solidified ash products were obtained by mixing and heating of powdered bottom Fe₃O₄-rich ash and glass waste paste in an inclined rotary incinerator. The chemical composition and structure of the product were analyzed by X-ray diffraction (XRD), scanning electron microscope/energy dispersive X-ray spectrometer (SEM/EDX), Fourier transformation infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS). The bulk sample mainly consisted of Fe₃O₄ and NaAlSiO₄, and glassy grain boundaries, which strongly bonded the ash to form a solid product. On the other hand, the surface of the product was covered by a Fe-free glassy layer of -10μm in thickness. The glassy surface layer was effective in preventing the dissolution of heavy metals (Pb, Cr) into aqueous acid solutions (2<pH<7).

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The 1950's and 60's were the decades when the field of traditional ceramics was brought under the light of analytical physical science. Especially sintering process of ceramics, which had been a matter of extreme complexity, was basically understood in terms of the atomistic diffusion process occurring in the bulk and/or on the interface of the coagulated body of the powder. On the extension a high temperature mechanical property, creep, was understood on a similar basis. The knowledge developed led to the discovery of highly dense sintered ceramics, now widely known as translucent ceramics.
The author started his career as a ceramist in late 60th when the understanding of sintering kinetics needed further elaboration. One of the apparent contradiction at the time was the fact that the faster diffusing species, i.e., cation in oxides was the rate determining one in the sintering process. There should be some process that enhances the diffusion process of oxygen. Gradually the importance of surface and grain boundary diffusion was paid attention. This review was written by the author in order to summarize many papers, appearing in those days and to establish the systematic view on those studies. He described how various processes involve the ionic diffusion and how grain boundary diffusion affects the processes based on the concept of the ambipolar diffusion. Starting from the accumulated knowledge in the metal and alkali halides as the simple model for ceramic materials, he related the scattered knowledge into a consolidated view that could be applied to ceramics.
In relation to this review he wrote additional reviews on “Diffusion Coefficient of Point Defects in Oxides” Yogyo-Kyokai-Shi, Vol. 87, No. 3, 36-42 (1979), and on “Kinetics of Various Mass Transport Processes on the Solid Surfaces, ” Oyo-Butsuri, Vol. 49, No. 6, 579-585 (1980) which in combination still form the basis of the current understanding of the field.

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