The structure of silicate glaze was studied by infrared reflection method.
The results obtained were as follows:
1. The main reflection peak (about 1100cm^-1) of silicate glasses shifted to lower wave number with the increse of content of basic and aluminium ions contained in the glass structure.
The effect of alkali, alkali earths, and aluminium ions on the Si-O bond shift became more remarkable with the increase of ionic valency and radius.
The causes of shift to lower wave number of the infrared reflection peak were considered to be as follows.
a. By the electrostatic interaction between cation and oxygen atom, the Si-O bond strength was decreased in the silicate glass structure as compared with silica glass.
b. The increase of number of cation in the structure of silicate glass extends the mean Si-O linkage of random network, and lengthens the atomic distance of Si-O bond, therefore weakens the Si-O field strength.
2. The cation entered into the structure of silicate glass broaded the peak, because the cation extends the network structure and consequently the field strength of Si-O bond becomes random.
That effect increases with the increase of electrostatic interaction between cation and oxygen atom.
3. The peak shifts to lower wave number, with the increase of number of cation in the structure of silicate glass.
But in the case of precipitating crystal in the glaze, wave number shifted to higher, for the reason that the effect of crystallization is dominant to peak shift and the field strength of Si-O bond increases.

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In order to improve not expensive, “regular grade” carbon fiber, a yarn of the carbon fiber prepared from lignin/poval was coated with pyrolytic graphite. Coating was carried out with methane of 10 Torr. in the temperature range of 1200°-1900°C at the gas flow rates of 35-420ml/min. (stp).
The properties of the carbon yarn coated with pyrolytic graphite depended upon the conditions in which it was deposited. Coated yarns with layer of pyrolytic graphites thicker than ca. 2μ were not so flexible.
The yarn was derived which was so strong as 59.08kg/mm²; or which lost only less than 10wt% in 5 minutes in the air of 900°C; or which had specific electric resistance of 3.569×10^-4Ωcm.

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Single crystals of stoichiometric spinel (MgAl₂O₄) were grown by flux method, using a mixture of PbO-PbF₂-B₂O₃ (1:1:x in weight ratio).
The crystals obtained were characterized by chemical analysis, measurement of etch pit density and X-ray diffraction topography (Berg-Barrett method).
Solubility of MgAl₂O₄ in the flux was determined by quenching method. An addition of B₂O₃ to the flux increased the solubility and suppressed the formation of MgF₂. The addition of excess B₂O₃ (more than 23wt%) resulted in the formation of 9Al₂O₃⋅2B₂O₃. The addition of 15-20 wt% B₂O₃ is recommended for growing MgAl₂O₄ single crystals. For these compositions, the flux has solubility ranging from 21 to 28g MgAl₂O₄/100g flux at 1200°C.
Etch pits were revealed on the {111} surface of the as-grown crystals by treat-ment with hot phosphoric acid. The pit density was approximately 10⁵pits/cm² and seemed to decrease with the addition of B₂O₃. The observed pit density was one order or more less than that of the crystals grown by the Verneuil method.
Chemical analysis showed that a molar ratio of Al₂O₃/MgO in the crystal was 1.00 within the experimental error.
X-ray topography revealed that the crystals were free from sub-boundaries.

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Microstructure and bending strength of a photoceram-type crystallized glass of the composition SiO₂ 81, Li₂O 12.5, K₂O 2.5, Al₂O₃ 4, CeO₂ 0.03, Au 0.027% in weight were studied with a particular attention to its surface structure. The results are summarized as follows;
1) The surface of both the samples heated up to 620°C and up to 900°C had a structure different from the interior. In the former lithium disilicate crystals were precipitated at the surface of the sample in addition to lithium metasilicate which was the only crystalline phase found in the interior. The lithium disilicate were oriented with the (002) plane parallel to the surface. In the latter the crystalline phases were lithium disilicate and α-quartz throughout the sample, but the lithium disilicate crystals oriented themselves at the surface.
2) The bending strength of the crystallized glasses obtained by heating up to 620°C was independent of the size of crystals found in the interior, before removing the surface layer, while it increased with decreasing grain size after the original surface layer was removed.
3) The strength of the crystallized glasses obtained by heating up to 900°C was intimately related to the size of crystal grains precipitated in the interior both before and after removal of the original surface layer; the strength increased with decreasing grain size. Presence of the strength-grain size relationship for the samples before removal of the original surface layer was explained by the fact that the length of the oriented crystals at the surface decreased with the grain size in the interior. The strength-grain size relationship for the samples after removal of the surface layer was explained by Orowan's theory on polycrystalline materials.

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The phenomenon is studied experimentally with sublimation procedure and the synthetic mothod using molten silicon out of the range 1400°-1600°C. From the consideration of molar surface energy for β- and α-SiC, next three points are shown as the main causes of the phenomenon. 1) In case of the volume of crystalite being the same, the molar surface energy of β-type is always smaller than the α-type based on its higher lattice symmetry. 2) The bond energy of β-type is considered to be smallest among many polytypes of SiC from the comparison of band gap. 3) The rate of transition from β-to α-type is not so large. From the experimental condition enough to grow β-type and the gap of molar surface energy between both types at these condition, it is predicted that the free energy gap between SiC polytypes must be less than 100cal/mole. The effect of pressure and the polarity are also discussed.

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A hydrothermal process of iron sulfide gives rise to greigite (F_d3m), pyrite (P_a3) and mackinawite (P_4/nmm), as the case may be. Greigite is blended with pyrite, when autoclave for the hydrothermal process is cooled down slowly from 192°C to room temperature. Greigite and pyrite here form partially a solid solution. A mixture consisting of greigite and mackinawite appears in the hydrothermal process below 192°C. Pure greigite is produced by means of rapid quenching of the autoclave from 192° to 10°C. 4 figs, 1 table, 5 refs.

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