Eu³⁺ containing 3Na₂O⋅42B₂O₃⋅55SiO₂ (mol%) glass was isothermally heat-treated for phase separation. The photoluminescence (PL) behavior of Eu³⁺ was investigated. It was found that PL intensity of ⁵D₀→⁷F₂ transition of Eu³⁺ increases with evolution of phase separation. A maximum 6.5 times increment in the PL intensity can be obtained after phase separation as compared to that of the as-cast sample. Moreover, the maximum increment of the PL intensity seems to be related to the texture induced by phase separation, the droplet texture being superior to the interconnected one. The mechanism of augmentation of the PL intensity was interpreted in terms of the derived expression of the PL intensity. It was then suggested that the induced interface after phase separation, causing remarkable increase in light scattering intensity and therefore notable increase in the population of Eu³⁺ on the ⁵D₀ energy level, accounted for significant enhancement in the PL intensity. On the other hand, from the emission intensity ratio of ⁵D₀→⁷F₂ to ⁵D₀→⁷F₁ transitions of Eu³⁺, it was estimated that Eu³⁺ partitioned into the borate-rich phase after phase separation.

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An ionic conductor, Ba β-alumina, was synthesized in a BaO-MgO-Al₂O₃ ternary system by solid state sintering at 2023 to 2073K. The Ba β-alumina with a composition of BaO:MgO:Al₂O₃=1:1:5 was in a single phase. Its relative density was 96% of the theoretical density. The electrical conductivity of Ba β-alumina was 4.6×10^-3S⋅m^-1 at 1673K and the activation energy was 126.82kJ⋅mol^-1. The mobile ion could be Ba²⁺, and its ionic transport number was about 0.8 to 0.9 at 1073 to 1673K.

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Titanium dioxide films were chemically prepared on (001) single-crystal strontium titanate, SrTiO₃, using a vapor deposition apparatus operating under atmospheric pressure with titanium tetra-isopropoxide. At a substrate temperature of 400°C, titanium dioxide grew epitaxially with lateral growth of steps, as well as multinucleation was observed during the initial growth process, i.e., the so-called Stranski-Krastanov growth. As a result, the surface of strontium titanate was completely covered by titanium dioxide steps with an average lateral growth rate of 100nm/s, followed by multinucleation growth. The nuclei developed in a number of highly oriented crystallites having well defined facets. X-ray diffractometry and transmission electron microscopy revealed that these crystallites consisted of ‹001›-oriented anatase-type structure.

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Zeolite fiber was manufactured from the nanosized ZSM-5 crystals. In this process, it was found that the size of zeolite particles (≤200nm) play critical role in the fiber formation. To obtain nanosized zeolite crystals, ZSM-5 zeolite was crystallized at the temperature of 80°C and the atmospheric pressure. The size of zeolite was observed to be dependent on Si/Al ratio. Si/Al ratio of 33 was optimum for the synthesis of 200-nm sized zeolites. The formation of zeolite fiber was also affected by the interaction between particles and solvent. High adhesion energy of zeolite particles seems to be required to form the fiber. ZSM-5 zeolite fiber was transparent because the size of zeolite particles is below the wavelength of visible light (400-700nm). The particle size of ZSM-5 fiber was found to be larger than that of TS-1 zeolite fiber (80nm).

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In order to evaluate the contribution of the non-180° domain reorientation in the electric-field-induced strains of PZT ceramics, a Mach-Zehnder interferometer was constructed and the electric-field-strain of PZT ceramics was measured as a function of frequency. The performance of the interferometer was confirmed using a LiNbO₃ single crystal and PZT ceramics. The piezoelectric constant of PZT ceramics determined by the interferometer well agreed with that determined by the resonance method and the result of LiNbO₃ single crystal was also approximately consistent with the literature. The resolution of the interferometer was about 0.01nm. The electric-field-induced strain curve showed a hysteresis under high electric fields and low frequencies. The apparent piezoelectric constant determined from the electric-field-induced strain increased with decreasing frequency under high electric fields. These behaviors were interpreted as the effect of non-180° domain reorientation.

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This paper reports some experimental results on a concave piezoelectric element, conical backing and first amplifier for high-sensitivity and wide-band AE transducer. The piezoelectric element, conceived according to a “resonance dispersion” design, was fabricated based on piezoelectric ceramics/polymer 1-3 connectivity composites by Newnham. To control ringing characteristics, the backing was conical in shape. The first amplifier was inserted in a FET zero-bias amplifier in a cable connecter. The AE transducer had half sensitivity and a wider resonance frequency (100kHz-1.9MHz) than a conventional type AE transducer (resonance frequency; 180kHz). The residual noise was 20μVp-p (10kHz-50MHz) at first stage amplifier, the measurement of hold level was able to reduce the noise to 10μV with a wide frequency. Using this AE transducer, AE measurement with a high-sensitivity and wide-band was realized in material testings.

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Total conductivities of yttria stabilized zirconia ceramics in series samples of (YO_1.5)_0.250-(Zr_0.750-xTi_x)O₂ and (YO_1.5)_0.550-(Zr_0.450-xTi_x)O₂ prepared through sol-gel route and transparent zirconia (Zr_0.772Y_0.134Ti_0.094O_1.933) have been measured by an ac impedance method as a function of oxygen partial pressure, P_O2, between 1073 and 1273K. The total conductivity showed an increase with decreasing the oxygen partial pressure at low P_O2 region by the enhanced contribution of the partial electronic conductivity. The partial conductivity of oxide ions, which is independent of P_O2, slightly decreased with increasing the TiO₂ content both of (YO_1.5)_0.250-(Zr_0.750-xTi_x)O₂ and (YO_1.5)_0.550-(Zr_0.450-xTi_x)O₂. The partial conductivity of electrons, proportional to -1/4 power of P_O2, showed a marked increase with increasing TiO₂ concentration at the same temperature and P_O2 conditions. Substitution of Ti⁴⁺ for Zr⁴⁺ decreases the formation enthalpy of oxygen vacancy, resulting in an increase of the concentration of electrons.

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In this study, the cause of the variation of strength and elongation of glass ceramics green sheet as a function of the dispersion medium of wet milling was investigated. Green sheets were made from a mixture of glass powders ground by wet milling, ceramic fillers, plastic binder and solvent. The used glass was consisted of MgO, Al₂O₃, SiO₂, B₂O₃ and K₂O. In case of using water as a dispersion medium, wet milled glass powder became porous, because MgO and B₂O₃ ingredients were highly dissolved into water solvent. Therefore, it was considered that a mechanical adhesion between glass powder and binder was enhanced, and green sheet with high tensile modulus and with low elongation was produced. On the other hand, in case of using xylene as a dispersion medium, the surface area of glass powder was much smaller than that by using water, because components of the glass did not dissolve. It was considered that the adhesive strength between glass powder and binder was low so that the elongation of green sheet was the almost same as that of binder only.

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Toughening mechanism of particle dispersed SiC composite was investigated from the stand point of the toughening places, crack tip and crack wake. Comparing the measurement results of toughness with SEPB method and SEVNB method, two toughening effects working at crack tip and in crack wake were separated. Measurement results of residual strain in SiC with XRD indicated compressive residual strain in particle SiC composite according to the kind of particle and its content. A linear relationship was found between the average compressive residual strains and the toughening effects at crack front independent to the kind of particles and their content, suggesting the toughening effect is caused by the generation of compressive stress field, At high temperature, residual strain was measured to decrease with XRD. Corresponding to the decrease, the toughening effect at crack tip decreased at high temperature. These results indicate that the thermal residual stress, which caused in the cooling process from the sintering temperature to the room temperature because of the higher coefficient of thermal expansion of dispersed particles than matrix SiC, reduced the stress intensity factor at the crack tip and the toughness of SiC increased. As for the toughening effect in crack wake, it was related to the fracture mode and the dispersed particle size. The toughening effect in crack wake was significant in the case of the fracture mode of particle boundaries and larger particle size. The temperature dependence of the toughening effect in crack wake was not large. These results indicate that the toughening effect in crack wake is caused by the particle bridging between fracture surfaces.

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A systematic and comprehensive study has been made on the influence of donor (La) content on the Curie temperature (T_C) and room-temperature conductivity of atmospherically reduced and re-oxidized ceramic bodies with the composition described by Ba_1-xLa_xTiO₃ (BTO) and Ba_0.8-xLa_xSr_0.2TiO₃ (BSTO), with x in the range 0-0.0054. The T_C of both materials, when reduced at 1300°C in Ar, decreased with increasing La content, indicating that oxygen vacancies can be created more easily by reduction at high temperature as the doping concentration of La increases. The room-temperature conductivity for BSTO and BTO materials, reduced at 1350°C in 95%N₂-5%H₂ and then cooled down to room temperature in the same atmosphere, was found to be significantly different from each other; the conductivity for the former materials showed a value almost twice as large as that for the latter over the whole range of La content. Significant difference has also been found in the decrease trend of room-temperature conductivity for the reduced materials when re-oxidized in air at elevated temperatures in the range 1200-1460°C. BSTO showed higher durability against oxidation than BTO; this may suggest a higher stability of oxygen vacancies formed in BSTO than in BTO. A significantly large decrease of the room-temperature conductivity up to an almost insulating level when reoxidized, resulting from the disappearance of oxygen vacancies, was observed for highly La-doped BTO materials. The results obtained in the present study suggest that (Ba, Sr)TiO₃ ceramics doped with La within 0.2mol% show a room-temperature conductivity dominated by the donor content, whereas for those with>0.2mol% La the room-temperature conductivity can be strongly influenced by the form of oxygen vacancies existing in materials and their stability during cooling to room-temperature.

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Monolithic Cs₂MSi₅O₁₂ (M=Cd, Ni, Zn) with cubic symmetry, space group Ia3d, was synthesized in air according to a two stage heat treatment. Mixed raw material powders were calcined at 973 to 1023K for 20 to 40h until the Cs₂MSi₅O₁₂ (M=Cd, Ni, Zn) phase were recognized by XRD and then they were heated at 1273 to 1473K for 20h. The thermal expansion of the synthesized Cs₂MSi₅O₁₂ (M=Cd, Ni, Zn) powders was investigated using high-temperature X-ray diffraction at 298 to 1273K. The Cs₂MSi₅O₁₂ (M=Cd, Ni, Zn) powders having SiO₄/MO₄^2-=5, displayed a lower thermal expansion than those of CsMSi₂O₆ (M=Al, Fe) having SiO₄/MO₄^-=2 in the low temperature range. With increasing the ionic radius of M²⁺, the thermal expansion coefficient of the synthesized Cs₂MSi₅O₁₂ (M=Cd, Ni, Zn) was increased in the low temperature range.

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To improve the oxidation resistance of carbon, carbon/ceramics composites were prepared from phenolic resin, ethyl acetoacetate aluminum di-isopropylate (ALCH) and boric acid by carbonization at 1300°C, 1600°C and 1900°C. Attention was focused on the oxidation resistance and crystallization of the carbon/ceramics composites. The result showed that carbon/ceramics composites with 9mass% of Al₂O₃:B(OH)₃=1:1, 1:2 and 0:1 had an optimum oxidation resistance, when heated at 1600°C. Samples containing ALCH were also heated to 1900°C and crystallization of carbon was observed.

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The fluidity of CaCO₃ suspension with various types of polymer containing graft chain of polyethylene oxide have been investigated. With increasing the dosage of polymer, the fluidity of suspension was increased. This is because the amount of retention water in clusters of CaCO₃ suspension is reduced by the steric hindrance effect of adsorbed polymer. The smaller the amount of retention water, the larger the fluidity of suspension. Over the amount of saturated adsorption of polymer, the fluidity of CaCO₃ suspension is increased gradually with the dosage of polymer. The viscosity of suspension with polymer having low molecular weight of graft chains is lower than that of suspension with high molecular weight of graft chain, because the amount of retention water in clusters of CaCO₃ suspension with polymer having shorter graft chains are smaller than that of CaCO₃ suspension with polymer having longer graft chains.

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Flow behavior of five kinds of glass melts upon application of a strong vertical magnetic field up to 2T have been studied. In the case of glasses containing glass network former (NWF) such as La₂O₃-B₂O₃, TiO₂-SiO₂, Nb₂O₅-P₂O₅ and La₂O₃-GeO₂ systems, no convection-current changes was observed. On the other hand, in the case of a glass (27Bi₂O₃⋅56PbO⋅17Ga₂O₃) without a typical NWF a pattern of large vortex current was observed in the range of 0.2 to 2T. This phenomenon may be applied both to develop a new non-contact mixing technique in glass melting for elimination of bubbles and glass defects such as streaks, and for obtaining better homogeneity of compositions. The relation between the change of convection current caused by the magnetic field and the structure of glass melts is discussed in detail.

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The melting of ash, including bottom ash and fly ash from municipal waste, is one of the effective way for reducing the volume of ash, making ash harmless and its recycling. For these purpose, it is necessary to melt it in lower temperature and to select the available way and its condition for melting process. In this report, physical and chemical properties of ash for melting were studied to select them. Harmlessness of slag which was important to evaluate the availability of melting process was examined by leaching test with acid solution. The melting temperature of ash and phase of slag had a closely relation with ternary diagram of SiO₂CaO-Al₂O₃ system. The lowest melting temperature was found in the basicity (CaO/SiO₂) of 0.9-1.0. The fluid temperature increased rapidly became melting more difficult in lower and higher ranges of basicity, 0.9-1.0. After melting ash, amount of leaching from slag became 10^-2-10^-3 smaller than ash before melting, showing that melting was the most effective way for making ash harmless. Property of leaching from slag was effected by its texture, especially that of non-crystal phase. It was concluded that the examination of leaching property was available to study the characteristics of melting process. It was also found that slag had to a prepared in lower basicity than 0.8-1.1, keeping the melting temperature lower, since amount of leaching from slag with eutectic texture in the range of basicity 0.8-1.1 was slightly increased.

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Low oxygen SiC fiber/Al interfacial reactivity was evaluated in comparison with that of an usual SiC fiber/Al interface. Chemical composition of low oxygen SiC fiber was Si: 62.4, C: 37.1, O: 0.5mass% and that of a usual SiC fiber was Si: 63.7, C: 35.8, O:12.3mass%. The outcomes of this study can be summarized as follows: (a) No product was detected at the low oxygen SiC fiber/Al interface. (b) The low oxygen SiC fiber-reinforced Al composite was higher corrosion resistance, and lower strength deterioration on compared with the usual SiC fiber-reinforced Al composite. (c) Al atoms diffuse into low oxygen SiC fiber during dipping into a molten Al with the diusivity of 6×10^-15m²/s. (d) In the initial stage of interfacial reaction, low oxygen SiC fibers are not eroded, but a needle-shape Al₄C₃ phase forms on the fiber surface. On the other hand, the SiC fiber can be eroded by the Al₄C₃ formation, when long time dipping in the molten Al under unfavorable conditions.

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The effect of powder characteristics (such as specific surface area and morphology) and iodine addition on the electrophoretic deposition (EPD) coating of alumina on Pt wire was investigated. Electrical conductivity of the bath solution was increased by adding iodine and depended upon specific surface area of alumina powder. Moreover, adding a suitable amount of iodine led to a remarkable improvement of stability of the bath solution, and uniform EPD layers resulted Round shaped alumina produced by chemical vapor deposition (CVD) method was more suitable than irregular shaped alumina made by sol-gel method for preparing thick and uniform layers. The difference of deposition behavior was explained in terms of electrical resistance of the formed alumina layer and the bubbling of H₂ gas generated during deposition. Crack-free alumina -50μm thick layers could be formed on Pt wire by sintering at 1500°C.

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A machinability of porous Si₃N₄ ceramics composed of columnar β-Si₃N₄ grains was evaluated by turning and milling with cemented carbide cutting tools to investigate a possibility of application of the porous Si₃N₄ to machinable ceramic use. The porosity and the flexural strength of specimens were about 43% and 270MPa, respectively. The machinings were carried out with a cemented carbide throw-away tip of K-10 grade. The condition of turning was cutting speeds of 50 to 150m/min, feed rates of 0.05 to 0.40mm/rev, and a cutting depth of 0.5mm, and that of milling was cutting speeds of 20 to 200m/min, feed rates of 0.05 to 0.20mm/rev and a cutting depth of 0.5mm. Machinability was judged from the maximum surface roughness, R_max, after machining; it was defined that a material was machinable when R_max was below 10μm. In the case of turning, the R_max increased with increasing cutting speed and feed rate. R_max below 10μm was obtained under conditions that satisfied both a cutting speed of 50m/min and feed rates below 0.1mm/rev. In the case of milling, although the R_max increased with increasing feed rate, serious cutting speed dependence of R_max could not be seen. R_max values below 10μm were obtained at feed rates below 0.1mm/rev, independent of cutting speed.

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CaCO₃-Ca(OH)₂ mixed powders, coated with a chelate compound of aluminum corresponding to 0-0.5mass% Al₂O₃, were sintered at 1500°C for 2h in order to obtain CaO ceramics. The relative density was 95% for Al₂O₃-free CaO ceramics obtained from the 29mol% CaCO₃-71mol% Ca(OH)₂ mixed powder. On the other hand, a low density of 86% was found in the CaO ceramics prepared from 100% CaCO₃ powder. The mass gain of Al₂O₃-free CaO ceramics and 100% CaCO₃ powder was about 40% and 80%, respectively, according to a slaking-resistance test of 360h under 95% relative humidity at 50°C. The sinterability and slaking resistance of CaO ceramics prepared from CaCO₃-Ca(OH)₂ mixed powder were remarkably increased compared with those prepared from CaCO₃ powder. The relative density and mass gain after slaking-resistance test were 97 and 12%, respectively, for the CaO ceramics prepared from the 29mol% CaCO₃-71mol% Ca(OH)₂ mixed powder coated with 0.01mass% Al₂O₃. The trace amount of Al₂O₃ coating on the starting powder led to an improvement of slaking resistance of CaO ceramics prepared from CaCO₃-Ca(OH)₂ mixed powder. The slaking-resistance of CaO ceramics prepared by Al₂O₃ coating method was higher than that obtained by conventional mixing of Al₂O₃ powder.

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The wet grinding of α-alumina powder with water is known to cause formation of aluminum tri-hydroxide on the particle surface of the powder by mechanochemical effects. The present authors have found that wet submicron-grinding of α-alumina powder using polyacrylic ammonium (PAN) as a dispersant can be performed without generation of hydroxide on the particle surface. In this study, the relationship between the amount of PAN and the formation of aluminum tri-hydroxide in wet rotation ball milling of α-alumina powder using water as a solvent was investigated. Without addition of PAN, hydroxide generated on the particle surface of α-alumina powder after 24-h grinding. On the other hand with the addition of 1.7mass% PAN, hydroxide did not generate after 168-h grinding. PAN was considered to be absorbed onto the AlOH₂⁺ sites of the particle surface of α-alumina powder and, thus, to disturb the generation of hydroxide. Grinding efficiency was not improved by addition of PAN during submicron grinding.

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Tension-compression biaxial strength was measured by anticlastic bending test for the laminated Si-Ti-C-O fabrics (10vol%)/mullite matrix composite. Biaxial strength of composite material was lower than that of monolithic mullite ceramics. According to observation of the fracture patterns and fracture surfaces, we assumed the fracture process of the composites in anticlastic bending test to a as follows. Firstly, microcracks were generated by residual stress due to the difference of thermal contraction between mullite and fibers. Secondly, the microcracks propagated and connected to form macroscopic cracks on the surface of specimen by the shear stress of the anticlastic bending test. Finally, mode II fracture occurred from the macroscopic cracks in the direction perpendicular to the tensile principal stress.

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High dielectric barium-strontium-titanate (Ba_0.5Sr_0.5)TiO₃ (BST) thin films were fabricated by a spincoating technique. The fabrication process consisted of three steps. First, a complex alkoxide was synthesized from barium, strontium and Ti-alkoxide (titanium tetraethoxide) in 2-methoxyethanol at 125°C for 3h. Then, hydrolysis and condensation reactions of the complex alkoxide were carried out at 75°C in 2-methoxyethanol containing nitric acid as a catalysis. Finally, the sols obtained by hydrolysis and condensation of Ba-Sr-Ti complex alkoxide were casted onto glass substrates. The films were subjected to heat treatment at temperatures between 350 and 900°C. The films started to crystallize into a perovskite structure BST at 500°C, and were well-crystallized at 525-550°C. The BST films that were heat-treated at 550°C had dielectric constant exceeding 2000 at 800Hz.

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