The evolved phases of spinel-type phase, mullite and cristobalite formed by calcining allophane, a clay mineral mainly composed of SiO₂, Al₂O₃ and H₂O, were characterized by various methods. Spinel-type phase was assigned to be γ-Al₂O₃ from the results of the lattice constants, infrared spectra, specific gravities and alkali extraction. Its chemical composition was considered to be nearly pure Al₂O₃ with little substitution of SiO₂. Mullite formed by calcining at 975°-1050°C contained an excess amount of Al₂O₃ over the composition 3 Al₂O₃⋅2SiO₂. On the other hand, mullite obtained at 1075°-1500°C developed prismatic shaped crystals which grew with increasing calcination temperature, and the composition was nearly 3Al₂O₃⋅2SiO₂. The lattice constants of cristobalite formed in calcined specimens were larger than those of pure ones, suggesting a possibility of substitutions of Al₂O₃ and Fe₂O₃ for cristobalite. More than 2% of Al₂O₃ and more than 1% of Fe₂O₃ are detected on cristobalite particles by an analytical transmission electron microscopy. Allophane was concluded to decompose firstly into γ-Al₂O₃ and amorphous SiO₂ with a little amount of mullite by calcination, which react to form mullite and that the remaining amorphous SiO₂ crystallizes into cristobalite at higher temperature.

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Optical absorption spectra of Ni²⁺ ions in (100-y)(PbO⋅SiO₂)⋅xK₂O⋅(y-x)Na₂O⋅0.2wt% NiO glasses were measured, and the results obtained were as follows.
(1) The spectra of the lead silicate glasses containing NiO showed three absorption peaks (ν₁, ν₂ and ν₃) in the vicinity of 5300cm^-1, 12000cm^-1 and 22200cm^-1. Two shoulders, ν₄(≅15600cm^-1) and ν₅(≅18500cm^-1), were also observed on the low wavenumber side of ν₃ absorption peak.
(2) In (100-x)(PbO⋅SiO₂)⋅xR₂O glasses (R=Na or K), in the case of R=Na, the value of 10Dq began to decrease significantly at Na₂O content of 10mol%, and when R=K, it decreased more sharply with increasing K₂O content. In (100-y)(PbO⋅SiO₂)⋅xK₂O⋅(y-x)Na₂O glasses, the 10Dq shifted toward the lower wavenumber side as (PbO⋅SiO₂) content decreased and K₂O content increased.
(3) In (100-x)(PbO⋅SiO₂)⋅xR₂O glasses, the value of Racah B parameter decreased slightly with increasing Na₂O content and was never below the level for free Ni²⁺ (=1030cm^-1) (R=Na), and decreased sharply below that level as the K₂O content increased beyond about 10mol%. The B parameter for mixed alkali systems decreased with increasing K₂O content and increasing total alkali concentration.
(4) In (100-x)(PbO⋅SiO₂)⋅xR₂O⋅0.2wt% NiO glasses, the intensity of ν₄/ν₃ showed slight and linear increase up to the Na₂O content of 20mol%. The ν₄/ν₃ ratio in the mixed alkali glasses increased nearly linearly with increasing K₂O content.
(5) The variation of absorption spectra of (100-y)(PbO⋅SiO₂)⋅xK₂O⋅(y-x)Na₂O⋅0.2wt% NiO glasses was explained on the basis of coordination of Ni²⁺ ions and electron density of oxygens.

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Binary compounds in the systems Ln₂O₃-Ga₂O₃ (Ln=La, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er, Yb) were studied by solid state reaction and a quenching technique using a heliostat-type solar furnace. In the systems, the existence of four types of compounds was shown; garnet-type 3Ln₂O₃⋅5Ga₂O₃ (Ln=Nd, Sm, Eu, Gd, Dy, Ho, Er, Yb), perovskite-type LnGaO₃ (Ln=La, Pr, Nd), monoclinic 2Ln₂O₃⋅Ga₂O₃ (Ln=La, Pr, Nd, Sm, Eu, Gd) and orthorhombic 3Ln₂O₃⋅Ga₂O₃ (Ln=Sm, Eu, Gd, Dy, Ho, Er). These binary compounds, except LaGaO₃, showed no phase transition during repeated heating and cooling cycles. In LaGaO₃, a reversible orthorhombic-rhombohedral transition was found to occur at about 900°C, using a high-temperature X-ray diffractometer. Most of the binary compounds melted congruently. With increase in the ionic radius of Ln, the solidification point decreased for LnGaO₃-type compounds and increased for 3Ln₂O₃⋅5Ga₂O₃-type and 2Ln₂O₃⋅Ga₂O₃-type compounds. Meanwhile, 3Ln₂O₃⋅Ga₂O₃-type compounds and 2Gd₂O₃⋅Ga₂O₃ were found to melt incongruently. The lattice parameters for the compounds showed shrinkage with the decrease of ionic radii of Ln. The refractive indices of the binary compounds were measured as follows: n=2.01-2.04 for 3Ln₂O₃⋅5Ga₂O₃, n_γ=2.05-2.06, n_α=2.04-2.05 for LnGaO₃, n_γ=1.95-2.01, n_α=1.93-1.99 for 2 Ln₂O₃⋅Ga₂O₃, and n_γ=2.01-2.05, n_α=2.00-2.02 for 3Ln₂O₃⋅Ga₂O₃.

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It is generally mentioned that there are α-β type transformations at the low temperature range in tridymite, cristobalite and quartz of silica. Therefore, it is important to study the influence of thermal cycle on the mechanical properties of silica refractories for effective use. Mineral compositions of the used silica refractory were tridymite (transformation tempreature: 117°C and, 163°C) and cristobalite (200°-275°C). The change of properties of refractories was investigated with acoustic emission, ultrasonic velocity measurement and high temperature microscopy. It was found that there were some relationships among the fracture initiation strength detected by AE, the ultrasonic velocity and the bending strength of the thermal cycled specimen. On the other hand, it was observed by AE and high temperature microscopy that fractures occurred at the first cycle in the range including the transformation temperature. Even in the range except the transformation temperature, the strength and ultrasonic velocity decreased without visible fractures with decreasing temperature. It is considered that this phenomenon was caused by microcracks in the microstructure.

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Porous glass prepared by acid leaching of phase-separated soda borosilicate glass usually contains colloidal silica which originates from the silica component in the borate phase. Molybdenum trioxide was added to the starting borosilicate glass to prevent the formation of colloidal silica. It promoted the opacification of the starting glass. Opaque glasses in as-cast state showed a spherical phase-separated structure and were amorphous by X-ray diffraction. The phase sepharation was related to the solubility of molybdenum oxide in the glass. The phase separation occurs at a high temperature and proceeds rapidly in the cooling process of the cast glass. Another type of phase separation, which was assigned to the phase separation in the ternary soda borosilicate glass, took place during the heat treatment of the opaque glasses. When the phase-separated structure of the heat-treated glasses is interconnected, the porous glasses composed of silica skeleton are obtained by the acid leaching of the phase-separated glasses. The colloidal silica in the porous glass increased with increasing silica content of the starting glass and at the same time the volume of the pores of skeleton decreased, markedly.

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The glass-forming region in the system CaO-Ga₂O₃-B₂O₃ was determined and Reman spectra of binary and ternary calcium gallo-borate glasses were measured and interpreted in terms of the structure. The glass-forming region expended near the Ga₂O₃/CaO=2 composition line, in comparison with CaO-Al₂O₃-B₂O₃ system where the glass-forming region extended to the Al₂O₃/CaO=1 composition line. The results have been interpreted from the fact that Ga₂O₃ has a lower melting point than Al₂O₃ and that Ga³⁺ is easier to form four-fold coordination with oxygen than Al³⁺. Raman spectra showed that boroxol rings, six-membered borate rings with one or two BO₄-tetrahedra, pyroborate groups and orthoborate groups were present in glasses in the high B₂O₃ region. Substitution of CaO for B₂O₃ changed the borate groups to those with one or two BO₄-tetrahedra and then to those with non-bridging oxygens. It was observed that Ga³⁺ was in the state of four-fold coordination with oxygen in most glasses. In the region of low B₂O₃ content, B³⁺ existed mainly in the form of an orthoborate group but a few of them existed in groups with BO₄-tetrahedra, Almost all Ga³⁺ were in the state of four-fold coordination with oxygen. GaO⋅2Ga₂O₃ crystal-like structure was also present in glasses of relatively high Ga₂O₃ content. The peaks at 680cm^-1 and 510cm^-1 are attributed to the Ga-O stretching vibration of GaO₄ and Ga-O-Ga bending vibration, respectively. Substitution of CaO for Ga₂O₃ leads to an increase in number of orthoborate groups, a decrease of borate groups with BO₄-tetrahedra and to the change of gallate network to the one containing more non-bridging oxygens. Compared with Al₂O₃, Ga₂O₃ tends to form two-component-like structurewith CaO rather than three-component-like one with B₂O₃ and CaO in this system.

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A large amount of cristobalite rock (SiO₂ 88.60%, Al₂O₃ 4.67%, Fe₂O₃ 2.38%, MgO 0.66%, CaO 0.63%, Ig. loss 2.91%; Total, 99.85 wt%) is deposited at Higashidori-mura, Aomori Prefecture, Japan. In this paper, synthesis of faujasite-type zeolite from the system cristobalite rock-sodium aluminate-sodium hydroxide-water was studied at low temperatures below 40°C and atmospheric pressure. The mixtures of cristobalite rock powder (1g), sodium aluminate, sodium hydroxide and water with the SiO₂/Al₂O₃ molar ratios ranging from 5 to 9, the Na₂O/SiO₂ molar ratios ranging from 1.5 to 5 and water 30ml or 50ml was transferred into plastic bottles. The bottles were closed with lids tightly and kept in an electric oven at 20°C or 40°C for time periods of 2 to 360h. The cristobalite rock powders reacted with sodium hydroxide solution and precipitated as a gel at 20°-40°C, and then faujasite-type zeolite, zeolite P or zeolite A were formed from the gel. The single-phase faujasite-type zeolite was obtained at 20°-40°C from the optimum mixture with the SiO₂/Al₂O₃ molar ratio of 5, the Na₂O/SiO₂ molar ratio of 5 and water 30ml per 1g of the cristobalite rock powder, and the relative crystallinity (%) of the synthesized faujasite-type zeolite was 28% at 20°C for 360h, 22% at 40°C for 48h and 61% at 40°C for 360h. No significant difference in the relative crystallinity (%) of the faujasite-type zeolite was found between the cases using the cristobalite rock and silica gel as a source of silica. The present results make the cristobalite rock attractive candidate for the synthesis of the faujasite-type zeolite.

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Contact angle measurements have been carried out on powders of amorphous arsenic chalcogenides using water, formamide, ethylene glycol, 1, 3-butanediol and 1-nitropropane as wetting liquids. The dispersion and polar components of the surface free energy, γ_S^D and γ_S^P, have been calculated from the geometric mean equation. Three approximations have been made in the present approach: (1) The relation between cosθ and (γ_L^D)^1/2⋅γ_L^-1 is linear (γ_L is the surface tension of the wetting liquid), (2) Near cosθ=1 the polar contribution is negligible as compared to the dispersion contribution, (3) The surface pressure is not taken into account for the case of θ>0°. The plots of cosθ of As₂S₅ and As₂Se₃ against (γ_L^D)^1/2⋅γ_L^-1 lie on the straight lines which can be obtained in the case where only the dispersive interaction is present. The γ_S^D'S of As₂S₅ and As₂Se₃ obtained from the slopes of the lines were 34.4 and 37.5mJ·m^-2, respectively. In the case of As₂S₃ both dispersion and polar components are considered to be present. The estimated γ_S^D was 25mJ·m^-2, while γ_S^P varied from liquid to liquid and was in the range of about 1 to 8mJ·m^-2. The present results are compared with those of organic polymers of low surfce energies.

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Formation of Li₃N thin film was investigated by nitriding the surface of lithium metal. The reaction process and the effects of atmospheric purity on the reaction were studied. The films having thickness of about 1mm were obtained at room temperature after a duration of 90min. The growth rate of the film decreased with increasing purity of nitrogen gas. The discharging current of 1μA could be attained for more than 1h on the Li/TiS₂ cell using the Li₃N film as electrolyte. The internal resistance of the cell was relatively high and the long-term discharging was not possible. The reason for the high resistance was discussed in relation to the lithium ionic conductivities measured on the compacted and the sintered bodles of Li₃N.

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The following methods were introduced in the manufacture of single crystals of emerald. (1) K₂MoO₄-MoO₃ was adopted as flux in place of Li₂MoO₄-MoO₃. (2) The effect of flux evaporation to accelerate crystal growth was examined. (3) The starting materials pre-calcined at lower temperatures to improve Cr³⁺ doping. (4) A new packing technique was devised for the starting materials and flux. The results obtained are as followS:
(1) In X₂MoO₄-MoO₃ flux system, the largest crystal length was achieved when X=K; 0.07mm longer for c-axis and 0.25mm longer for a-axis compared with X=Na, and 0.73mm longer for c-axis and 0.11mm longer for a-axis compared with X=Li.
(2) Aided by the flux evaporation effect, a single crystal measuring 1.98mm×0.77mm (for c-axis and a-axis, respectively) was obtained at a cooling rate of 8.33°C/h and a soaking temperature in the range of 1000° to 1140°C.
(3) When Al(OH)₃-Cr(OH)₃ coprecipitate was used as dopant in place of conventional α-Cr₂O₃ and it was pre-calcined together with the starting materials at 800°C for 10h, density of green color increased.
(4) When the starting materials were packed in the lower part of the crucible and flux in the upper part, the product became uniformly dispersed throughout the crucible, giving a single crystal measuring 2.45mm and 1.30mm (for c-axis and a-axis, respectively) at a soaking temperature of 1200°C.

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The unsupported thin-films of Al₂O₃, Al₂O₃-SiO₂, SiO₂, ZrO₂ and MgAl₂O₄ were prepared without the aid of temporary substrates. Each thin film of the precursor solution containing surfactaut was formed in a frame of platinum wire, dried and heated to 900°C or 1000°C. The green films were more or less wavy except that of MgAl₂O₄. The oxide films were from 1 to 4μm thick and transparent or translucent.

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