PZT thin films for microsensors and microactuators were prepared from lead acetate and zirconium, titanium alkoxide solution by sol-gel processing. High-performance, crack-free, thin (3.1μm) films were acquired by multiple coating, and high-temperture annealing.
PbO evaporation occurred on firing. This is caused by the lack of Pb and the structure is divided into a perovskite phase and the amorphous and/or nanocrystal regions. The existence of the amorphous and/or nanocrystal region reduces the dielectric and piezoelectric constants. Excess Pb diminishes the amorphous and/or nanocrystal region and improves the piezoelectric and ferroelectric properties.
A 20mol% Pb excess PZT film has good piezoelectric properties. The dielectric constant ε_r, the piezoelectric constant d₃₁ and the spontaneous polarization P_s are 1800, 30.0×10^-2C/m² and 39.2×10^-12C/N, respectively. These values are similar to those of bulk PZT ceramics. This PZT film will be used in the fabrication of microactuators and microsensors.

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Effects of gold nanoparticle incorporation on the photoanodic properties were studied for fluorescein-, rose bengal- and nile blue A-deposited TiO₂ film electrodes prepared by the sol-gel method. The incorporation of gold particles decreased the dye-induced photoresponse in the visible region, which was ascribed to the retarded electron transport in the conduction band due to the Schottky barriers at titania/gold interfaces. The extent of decrease in photoresponse, however, was the smallest for the electrode sample with rose bengal, whose optical absorption well overlapped the surface plasma resonance of the gold particles. The dipole-dipole coupling between rose bengal molecules and gold particles was thought to enhance the photochemical processes, resulting in smaller reduction in the photoresponse.

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The pyrolysis for Nicalon alone and the Nicalonalumina compact was investigated under an N₂ atmosphere at 1773 to 1973K. The pyrolysic behavior under an N₂ atmosphere was compared with that under an Ar atmosphere reported previously. The following results were obtained.
(1) At 1773K, the pyrolysis for Nicalon alone was suppressed highly under an N₂ atmosphere. However, Nicalon in alumina powder pyrolyzed comparably under both atmospheres. Consequently, the presence of alumina powder caused the severe pyrolysis under an N₂ atmosphere. At 1973K, the pyrolysis was retarded in alumina powder, regardless of atmospheres. The pyrolysis under an N₂ atmosphere is retarded by the nitrified layer at lower temperatures and by the alumina layer at higher temperatures.
(2) The fiber-like AlN was deposited on the surface of the Nicalon-alumina compact.
(3) On heating Nicalon in alumina powder, it crystallized into α-SiC of type 2H as well as β-SiC.

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The multi-star β-SiC and SiC/TiC composites have been deposited by CVD method on graphite substrate. The precursors, SiCl₄, TiCl₄ and C₃H₈ were used as silicon, titanium and carbon sources, respectively, and hydrogen as a carrier gas for deposition. The morphology of surface and polished cross section for the SiC and SiC/TiC composite deposited was observed by SEM. The crystal orientations and microstructrure were analyzed by XRD and TEM. The growth propagation of the multi-star β-SiC and the SiC/TiC composites is attributed to the twin-plane-reentrant-edge mechanism. The [220] is an intensely preferred orientation as the twin axis of interpenetration twin configuration. The interface of SiC/TiC is severely strained as found in TEM image and dislocations are generated in the TiC phases owing to the mismatch of coefficient of thermal expansion.

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Leaching process in the preparation of porous glass from fluorine containing sodium borosilicate glass was intensively investigated under different conditions of phase-separation temperature, the thickness of specimens and the amount of acid leaching solution. Techniques employed are pore size distribution measurements and SEM observation with focusing on the leaching of SiO₂ component from the B₂O₃-rich phase. The pores formed in the inner part of specimens, after being treated with 0.5mol/l sulfuric acid solution of 200ml/(g-specimen) at 92±1°C for 0.5h, had a smaller size than those formed in the surface layer of specimens. Those smaller pores contained a larger amount of silica-gel which precipitated from the B₂O₃-rich phase in the leaching process. This is the cause why a bimodal pore structure was inevitably obtained through the course of leaching: the silica-gel was removable by leaching with a larger amount of acid solution for a prolonged time. In the early stage of leaching process, the dissolution of the B₂O₃-rich phase proceeds, forming smaller pores with residual silica-gel, and the silica-gel is subsequently removed from the smaller pores resulting in enlargement. This diffusion-controlled process proceeds from the surface of the specimen to its inner part, indicating that a thin specimen is effective to accomplish the complete removal of the silica-gel with a minimum amount of the leaching solution.

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Thin films of LiSbO₃ were prepared from metal alkoxides by a spin-coating method. LiSbO₃ films on quartz glass and sapphire (001) substrates heated in a flowing mixture of water vapor and oxygen showed preferred orientation to the (001) plane, whereas LiSbO₃ film on quartz glass substrate heated in air did not show preferred orientation. The thickness of the films with and without preferred orientation could be controlled to be 1 and 2μm by a single spin-coating, respectively. The electrical conductivities of the films were determined in the temperature range of 380-600°C. The electrical conductivity of the LiSbO₃ film with preferred orientation was one order of magnitude or more larger than that of LiSbO₃ film without preferred orientation.

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The effect of Ti/Sr ratio on the grain growth of La-doped SrTiO₃ ceramics sintered at 1400-1490°C for 2h in 5% H₂-95% N₂ with precisely controlled Ti/Sr ratio of 0.96-1.04 was investigated. The grain size was maximum at Ti/Sr ratio of 1.000 and remarkably decreased with excess amounts of Sr and Ti above 1470°C. However, the grain size was 2μm and almost constant below 1440°C regardless of the composition. The bulk density was almost constant (97%) in the Ti excess region, but decreased remarkably by addition of excess Sr. The microstructure was divided into three types depending on the Ti/Sr ratio and sintering temperature; (1) Sr rich region, (2) Ti/Sr≥1 and above 1470°C, (3) Ti/Sr≥1 and below 1440°C. In the early stage, the nuclei of remarkably grown grains were formed and their amount and the grain growth rate were dependent on the Ti/Sr ratios.

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Calcium carbonate whiskers (aragonite phase) are prepared by blowing CO₂ gas into the suspension consisting of Ca(OH)₂-added MgCl₂ aqueous solution. The shape and crystalline phase of CaCO₃ depend on the preparation conditions. The optimum conditions for preparing the aragonite whiskers were determined. The whiskers have high aspect ratios ranging from 20 to 40 with diameters of 0.5-2μm. A simple method for preparing aragonite whiskers by applying a carbonation process using MgCl₂ aqueous solution was developed.

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Glass-ceramics were searched for in the systems based on CaO-MgO-SiO₂-TiO₂-Ag₂O. The glasses melted at 1500°C could be cast. The absorptions were measured. Silver colloids formed in the glasses of composition CaO⋅MgO⋅2SiO₂⋅0.375TiO₂⋅0.007Ag₂O, and CaO⋅MgO⋅2SiO₂⋅0.49TiO₂⋅0.007Ag₂O. The crystallization of diopside of these glasses are controlled by volume nucleation and growth processes. It is shown that the activation energy for crystallization of diopside decreases of these glasses. A fluidity of diopside glass was observed at 800-900°C by the viscous flow mechanism. It can be formed precisely and crystallized under pressure of 0.15MPa at 850°C for 40min, and the glass-ceramics contained crystalline diopside. The bending strength was about 350MPa. This glass-ceramics crystal phase look similar to natural teeth in color and translucency without any deformation. Such a press-forming method is superior to casting method because it is free from pores, and it can be formed lower temperature than 900°C regardless of the glass has high melting point.

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The effects of impurities on piezoelectric constant and the strain characteristics were investigated for ceramics with the composition of (Pb_0.95Sr_0.05)(Zr_0.54Ti_0.46)O₃. The piezoelectric constant d₃₁ of samples doped with Nb and W was larger than that of non-doped samples, and d₃₁ of samples doped with Fe and Ni was smaller than that of non-doped samples. It was found that the actually found strain (δ) under high DC electric field was larger for donor doping and smaller for acceptor doping. In all samples, the δ values were larger than the calculated strain (δ_cal) obtained by multiplying d₃₁ by DC electric field. This result suggested that the strain (δ_p) of domain orientation due to electric field exists. The δ_p values of samples doped with donor were larger than that of non-doped samples, and those of samples with acceptor were smaller than that of non-doped samples. We found that δ_p is related to the binding force of domain, and that the binding force of domain is dependent on the internal field of space charge produced by dopants.

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Dry grinding of raw flaky graphite was carried out using a planetary mill in the presence of additives such as tri-sec-butylaluminate, 1H, 1H, 5H-octafluoropentanol and 1-pentanol. Each of the additives proved effective in accelerating the size reduction of the graphite, along with in making thin platy particles. The agglomeration of powders and the ball coating were not observed during the grinding, indicating that the additives spread over on all surfaces including the newly born surface of the particles resulting in a decrease in surface energy. Fluoropentanol having a high acidity showed a relatively higher effectiveness of grinding aids than 1-pentanol. The function of the aids for thinning particles has been explained; i.e., the chemisorption of the additive molecules on the broken bond plane of the graphite probably facilitates the fracture of particles along the cleavage planes.

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In this paper the most suitable addition ratio of Al(OH)₃ for the growth of needle-shaped β-LiAlO₂ crystals with diameters ≤1μm and length/diameter ratio ≥10 was examined in the LiOH-Al₂O₃-Al(OH)₃-NaOH system. The needle-shaped β-LiAlO₂ crystals with a diameter of 0.9μm, length of 10.4μm and a length/diameter ratio of 11.6 was obtained at a molar ratio of 41.7:7.3:6.2:44.8 in the LiOH-Al₂O₃-Al(OH)₃-NaOH system. It was revealed that the needle-shaped β-LiAlO₂ crystals were converted to γ-LiAlO₂ crystals without morphology change by heating from 750 to 1000°C for 10 or 30h. The surface area of resulting needle-shaped γ-LiAlO₂ crystals was from 16 to 17m²/g. The stability of the needle-shaped γ-LiAlO₂ crystals in alkali carbonates, the electrolyte of molten carbonate fuel cells, was examined. The needle-shaped γ-LiAlO₂ crystals derived from β-LiAlO₂ at 900°C for 10h underwent no deformation by the heat treatment at 650°C for 1000h.

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It is shown that final-stage densification and creep behavior of hot-isostatically pressed (HIP) Si₃N₄ materials are phenomenologically related by a simple law independently of the particular mechanism mainly affecting the behaviors. Data from fifteen Si₃N₄-based (HIPed) materials were examined taking as reference material a Si₃N₄ polycrystal densified without external addition of additives. Three main mechanisms were identified and discussed leading to either softening or hardening effects on Si₃N₄. They were grain-boundary softening, solid-solution softening and dispersion hardening as produced by adding to the reference system various additives with or without solubility in Si₃N₄ and hard ceramic dispersoids, respectively. It is phenomenologically recognized and quantitatively established that a common driving force acts in opposite directions during densification and creep processes.

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Solar control glass often becomes an obstacle to television broadcast wave reception inside a room, because coated conductive films can reflect incident electromagnetic waves with frequencies lower than that of the plasma oscillation of the films. Results of calculation of reflection coefficients from theoretical equations showed that the radio wave reflection from solar control glass decreases by dividing the conductive film into discontinuous segments with a periodic array. The segmental effect has been examined experimentally. Experimental results for the system of periodic conductive segments fixed on soda lime silicate glass agreed very well with the theoretical results when the edge effect of the array was very small. It was found also the power reflection coefficients for aluminium foil segments of 25mm square were less than 0.05 below 200MHz.

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Mixture of ¹⁸O₂ and ¹⁶O₂ gases was used as a tracer in oxygen diffusion experiment of solid (Y-TZP) in which the concentration of ¹⁸O in the gas phase was determined directly by a mass spectrometer. If a simple mixture of these gases was used, the formation reaction of ¹⁸O¹⁶O gas had an effect on the concentration determination, especially when the diffusion time was short. In order to go around the effect, it was essential to use a gas mixture in which oxygen isotope exchange reaction (formation reaction of ¹⁸O¹⁶O gas) was in equilibrium at the diffusion temperature.

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A glassy solid electrolyte of the (1-x)PbI₂-xPbO system was prepared using two kinds of quenching methods. In the case of the iron pressing method, 0.68PbI₂-0.32PbO (x=0.32) glass was obtained when PbI₂ melt reacts with oxygen in air. In the case of the quenching method using ice water, the glassy sample was not obtained when x<0.35. Conductivity was enhanced and crystallization temperature was decreased with decreasing PbO content x. A maximum conductivity of 6.2×10^-7S·cm^-1 at 373K was obtained for x=0.32 glass plate prepared by the iron pressing method. This value is almost equal to the maximum conductivity of anion conducting glasses reported. I^- ions would be the sole carrier ions, based on an estimation of the electromotive force of the I₂ concentration cell.

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Two kinds of compressive creep tests, in which creep-load was applied parallel and perpendicular to the hot-pressing direction, were conducted on hot-pressed β-Si₃N₄ whisker/SiALON composites at temperatures between 1275°C and 1350°C under 30-100MPa. The creep rate in the former parallel test was higher than that in the latter perpendicular test at the apparent steady state creep regime. The values of β-SiAlON (101)/(210) XRD peak area ratio on the cross-sectional plane perpendicular to the creep-loading direction were 1.51 and 0.26 in the perpendicular and in the parallel testing specimens, respectively. After creep, they decreased to 1.1 and to 0.23 in the perpendicular and in the parallel tests, respectively. In addition, the microstructural analysis revealed that the shape of SiAlON grains changed by the preferential grain growth through the solution/precipitation process. These results indicate that the enhancement of creep rate due to high orientation of grains is induced by the increase in a rate of dissolution of grains during creep.

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The Judd-Ofelt parameters, spontaneous emission probabilities from the ⁴F_3/2 level, quantum efficiency, and stimulated emission cross section of the ⁴F_3/2→⁴I_11/2 transition for Nd³⁺ are studied for potassium tantalum and lead bismuth gallate glasses. The results reveal that the tantalum gallate glasses have high Ω₂ values being comparable to that of Ge-Ga-S glass. The lead bismuth gallate glasses have high stimulated emission cross sections over 4pm² because of their high refractive indexes. The variations of the JO parameters with composition are discussed in terms of glass structure.

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