Fine-sized LiMn₂O₄ powders were prepared by solid-state reaction method using the nano-sized manganese oxide powders. Nano-sized manganese oxide powders obtained by spray pyrolysis from spray solution with citric acid and ethylene glycol formed the fine-sized LiMn₂O₄ powders with regular morphology by solid-state reaction method with LiOH. The mean sizes of the LiMn₂O₄ powders prepared from the nano-sized manganese oxide increased with increasing the post-treatment temperatures. Nano-sized LiMn₂O₄ powders with regular morphology were obtained at low post-treatment temperatures below 800°C. The LiMn₂O₄ powders post-treated at 800°C had the mean size of several hundreds nanometer and the narrow size distribution. The initial discharge capacity of the fine-sized LiMn₂O₄ powders prepared by solid-state reaction method using nano-sized Mn₂O₃ powders was 127 mAh/g. The discharge capacities of the LiMn₂O₄ powders dropped from 127 to 112 mAh/g by the 50th cycle at a current density of 0.1 C.

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The electrochemical properties of LiNi_1-yAl_yO₂ (0≤y≤0.1) powder prepared by emulsion method were investigated. The emulsion-derived powder was calcined at the temperature range of 700-800°C for various times. A single phase of LiNi_1-yAl_yO₂ solid solution was formed at 750°C. The composition of LiNi_0.99Al_0.01O₂ synthesized at 750°C for 36 h demonstrated the largest discharge capacity and showed an improved cycle life. The initial and final discharge capacities were 168 and 156 mAh/g, respectively, during 20 cyclic tests. The fading rate in discharge capacity after 20 cycles was only 7%, which was lower than the 8.7% of LiNiO₂. The optimum condition for the synthesis of LiNi_1-yAl_yO₂ was by heating at 750°C for 36 h in an oxygen stream.

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Recently, it was reported that the alkaline niobate-based (K, Na, Li)(Nb, Ta, Sb)O₃ (LF4) perovskite ceramics showed excellent piezoelectric properties and has been regarded as a new candidate of lead-free piezoelectric materials. However, the effects of additives on the piezoelectric property of LF4 have not been studied intensively so far. In this study, the effect of MnCO₃ addition to the LF4 was investigated. The sample showed a tetragonal phase at room temperature. The MnCO₃-doping changed the LF4 to “hard” piezoelectric ceramics with an improvement of Q_m from 26 to 73.

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A few mol% Al₂O₃-doped ZnO sintered body forms a substitutional solid solution and the semi-conducting property is drastically affected by the content of the dissolved Al. It was suggested from the results of XRD and EPMA that Al existed in the ZnO sintered body in the form of ZnAl₂O₄. Furthermore, the distribution of ZnAl₂O₄ was visualized by AFM and SEM. It was, however, difficult for these techniques to detect dissolved Al in ZnO grains directly. The SIMS mapping suggested that the trace amount of Al (approximately 0.3 atomic%) dissolved into ZnO grains because of high sensitivity for trace impurities. This result was consistent with the change in lattice constants of ZnO with Al dissolution.

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The luminescence characteristics of Te- and Bi-doped glasses and glass-ceramics were investigated and the origin of coloration and near infrared luminescence was discussed. The colorations of these glasses and glass-ceramics might be due to the elemental clustering, such as Te₂/Te₂ ^- and Bi₂/Bi₂ ^-. The broad near infrared (NIR) luminescence can be detected in Te- and Bi-doped glasses and glass-ceramics. The electron spin resonance (ESR) signal at g≈2.0 was observed in Te- and Bi-doped glasses and glass-ceramics, which exhibit NIR luminescence, and therefore this ESR signal is strongly related to the NIR luminescence. The ESR signal at g≈2.0 might be derived from molecular ions of Te and Bi, Te₂ ^- and Bi₂ ^-. Consequently, it is suggested that the broad NIR luminescence of Te- and Bi-doped glass and glass-ceramics are most likely to be caused by elemental clustering, such as Te₂/Te₂ ^- and Bi₂/Bi₂ ^-.

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Dielectric relaxations were investigated for the solid-solution system Ce_1-xSm_xO_2-δ(0.0≦x≦0.5), which is a typical oxide-ion conductor. The dielectric constants showed anomalously large values at low frequencies and high temperatures. Computer simulation clarified that the anomalously large dielectric constant (ε_r′) originated from the superimposition of both Debye-type polarization and interfacial polarization between electrolyte and electrode. Two kinds of Debye-type relaxation observed were ascribed to defect associates, (Sm_Ce′-V_O^••)^• and (Sm_Ce′-V_O^••-Sm_Ce′)^×. The Debye-type polarization was also confirmed by analyzing the dielectric loss factor (ε_r″). When the oxide-ion conductivity decreased in the heavy Sm-doped samples, the Debye-type polarization also disappeared, suggesting that ordering of oxygen vacancy suppressed the electric field response of Debye-type polarization.

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In this paper, the effect of the heat treating process for silver-carried zirconium phosphate antibacterial agent on its structure and component was investigated by X-ray diffraction (XRD), differential scanning calorimetry (DSC), transmission electron microscopy (TEM) and energy dispersive X-ray analysis (EDX). Its antibacterial activity and light permanency were also studied. The optimal heat treating temperature for antibacterial agent was 900°C, and the obtained antibacterial agent displayed uniform network structure as well as its crystal structure was almost the same as that of carrier except for small enhancements in the crystal space distance. When the treating temperature rose to 1100°C, the obtained antibacterial agent was irregular in shape ascribing to serious conglomeration, and its crystal structure began to decompose, whereas its mass fraction of element was not obviously affected. Moreover, increasing heat treating temperature, the light permanency improved, but the antibacterial activity declined. The antibacterial agent treated at 900°C possessed an excellent antibacterial activity with the the minimum inhibitory concentrations (MICs) against E. coli and S. aureus of 100 mg•l^-1 and 150 mg•l^-1, and good light permanency with the whiteness of 86.4% after exposure to UV light for 24 h. Furthermore, the antibacterial agent treated at 1100°C displayed some antibacterial activity and preeminent light permanency.

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The composite in Al₄SiC₄-AlN and Al₄SiC₄-AlN-C system were sintered by a spark plasma sintering method. The powders of metal Al, Si and carbon black and AlN as starting materials were mixed. The mixture was calcined at 1300°C and sintered at 1600° to 1800°C by spark plasma sintering. Shrinkage during sintering, density, microstructure and phase of sintered bodies were measured. X-ray diffraction analysis gave Al₅SiC₄N (15R) and AlN (2H) phases in the bodies sintered at 1750°C. Densification did not occur in some composition in 50 to 80% AlN of the system Al₄SiC₄-AlN, but their densification was accelerated by addition of carbon. By the analysis of shrinkage during sintering and SEM observation of microstructure, the grain of Al₅SiC₄N (15R) and AlN (2H) grew, and pore exclusion was obstructed in the system Al₄SiC₄-AlN, though the grain did not grow, and pore exclusion was accelerated in the system Al₄SiC₄-AlN-C.

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Machined alumina containing 20 vol% SiC whiskers have been subjected to various heat-treatments. The effect on local fracture stress has been investigated as a function of crack-healing temperature and time. By heating at 1673 K for 10 h, the machined specimen was fractured not from the cracks introduced by the hard machining but from the other region. Thus, it was concluded that the machining cracks were completely healed by this heat treatment. Moreover, the strength at elevated temperatures of the healed samples exhibited similar properties to the healed polished samples. It can be demonstrated that the crack-healing was useful for an increase in the strength of machined ceramics economically.

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Reaction-bonded silicon nitride has a potential to lower in cost, since it can be fabricated from low-cost silicon powder. However, because nitridation of silicon is an exothermal reaction, difficulty has been encountered in fabricating thick sintered bodies that exceed 20 mm. In this work, low-cost, thick silicon nitride was fabricated by reaction bonding and post-sintering, and its characteristics and problems were investigated. The obtained silicon nitride showed strength of approximately 500 MPa and fracture toughness of 4.2 MPa m^1/2. In fabricating a thick body, powder preparation seems to be an important factor in attaining stable mechanical properties.

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According to phase-contrast microscope analysis based on the JIS A 1481: 2006, chrysotile in the asbestos-containing building material waste was not detected after heating at 800°C for over 2 h. The asbestos-cement which was ground to below 180 μm after heating asbestos-containing building material waste at 800°C for 3 h was added into OPC to fabricate secondary cement product. When 50 mass% of the asbestos-cement was added to OPC, the compressive strength of the secondary cement product after 7 days was 32 MPa. Further chrysotile was not detected in the secondary cement product using phase contrast microscope analysis.

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Ca-α SiAlON powders were synthesized by carbothermal reduction nitridation (CRN) of zeolite (Ca-zeolite Y). First, the Ca-zeolite Y was converted into an amorphous phase below 1100°C, and then into Ca-α SiAlON via mullite, Si₂N₂O and (Ca, Si, Al)_xO_y liquid at 1450°C. In converting zeolite into Ca-α SiAlON, it was found that Ca-α SiAlON particles were of a similar size to that of the raw material, indicating that it is possible to control the particle size of Ca-α SiAlON using zeolite as a raw material.

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