In order to obtain fundamental data on the behavior of iron oxide, titanium oxide and other impurities in the clay refractory at high temperatures, corhart particle was heatedd from 800° to 1300°C in oxygen, nitrogen or CO stream. The corhart particle used consisted of mullite, α-alumina and glass matrix.
The variation of lattice constant of α-Al₂O₃ and color change of the particle were examined and thermal stability of corhart particle was discussed. Results obtained were as follows:
1) a₀₃₀ of α-Al₂O₃ extracted from the corhart particle and heated in oxygen stream. was slightly smaller than those of ones heated in nitrogen and CO stream.
2) a₀₃₀ of α-Al₂O₃ in the corhart particle and in the mixture of α-Al₂O₃ and mullite showed different tendency from that of α-Al₂O₃ extracted from the corhart particle. a₀₃₀ of the former heated in oxygen or nitrogen gas decreased with the increase of temperature, while in CO gas it got smaller at 1100°C than at 1300°C.
c₀₀₂ of mullite heated at 1300°C in oxygen or nitrogen gas decreased as compared with one before heated. In the specimen heated in CO gas, c₀₀₂ was smaller at 1100°C than at 1300°C.
This tendency was in agreement with the color change and the result of the chemical analysis. Decomposition of the solid solution of impurities in the mixture of α-Al₂O₃ and mullite was observed at relatively low temperatures in a reducing atmosphere. This might be attributed to the effect of coexisting materials and the reducing atmosphere.
3) Thermal stability of the corhart particle containing glass matrix was similar to that of the mixture of α-Al₂O₃ and mullite, and decomposition of the solid solution of impurities in α-Al₂O₃ occured at about 500°C.

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An apparatus of a laboratory scale was constructed for the direct formation in sheet form of arsenic-sulfur glasses by the distillation of raw glass batches under normal pressure. The present apparatus comprises a vertical distillation chamber, a batch container kept in the chamber, and a condensate depositer attached at the bottom of the chamber. The following materials are easily available for making the distillation chamber, batch container and condensate depositer: silica glass, 96% silica glass and glazed porcelain. Aluminum metal is especially recommended as a material of the condensate depositer with good temperature uniformity. By modifying the inner shape of the condensate depositer, arsenic-sulfur glasses can be directly formed in shapes of disk, square plate, circular and square rods, wedge, hemisphere, prism, and so on.
The optimum temperature condition of operating the above apparatus for the direct formation of transparent arsenic-sulfur glasses was as follows: 470°-550°C. for the temperature of batch container; 330°-430°C. for that of condensate depositer. The X-ray diffraction measurements on transparent sheets condensed under the above optimum temperature condition of distillation and on their crushed. powders showed that these sheets were glassy.
When the batch container of about 30ml. capacity and about 45mm. diameter was used, it usually took 3-6 hours after starting to heat the container to condense a glass disk of about 40mm. diameter and 3-4mm. thickness under the above temperature condition of distillation. It was desirable for the condensation of a glass disk with larger diameter and thickness than the above to increase the capacity of the batch container; one of the effective methods for increasing the rate of the glass condensation was to increase the diameter of the batch container.
The composition of condensed glasses was usually within the range of about 61 weight % As (As₂S_3.0) to about 65 weight % As (As₂S_2.5) when the composition of raw glass batches was As₂S₃ and/or As₂S₃+S(mole ratio). The arsenic content of condensed glasses was decreased with decreasing the arsenic content of raw glass batches, and the composition of the glasses was usually within the range of about 34 weight % As (As₂S_9.0) to about 54 weight % As (As₂S_4.0) when the composition of raw glass batches was As₂S₃+8S(mole ratio). The arsenic content of condensed glasses was decreased with lowering the temperatures of the batch container and/or the condensate depositer when the composition of raw glass batches was kept constant.
Mixtures of arsenic and sulfur in the powder forms were also available as raw glass batches for the direct formation of arsenic-sulfur glasses; the temperature of operation in this case was nearly equal to the above case using raw glass batches of the arsenic trisulfidesulfur system.

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The effect of various matrials added to γ-Fe₂O₃ on transformation into α-Fe₂O₃ was investigated by means of D. T. A., high temperature X-ray diffraction technique and others. The promotion of transformation by addition of metallic compounds such as metal oxides and metal salts, which was widely confirmed in many other reactions taking part in solids, was hardly recognized in this study, howevever, the immersion of γ-Fe₂O₃ into mineral acid solutions such as hydrochloric acid and sulfuric acid solution had the remarkable effect on this transformation.
The obtained results are summarized as follows:
(1) Such a effect by the immersion of γ-Fe₂O₃ into hydrochloric acid and sulfuric acid solution disappeared by washing till the sample got free from chloride and sulfate ions absorbed on it. This result allows us to consider that the accelerating action for this transformation does not relate to degraded particle size of γ-Fe₂O₃.
(2) γ-Fe₂O₃ treated with two mineral acid solutions was locally converted, espevially in its surface, to FeOCl and hydrated FeSO₄ respectively by the reaction with the mineral acids at elevated temperature.
(3) The beginning temperature of the transformation of the treated γ-Fe₂O₃ coincided completely with that of thermal decomposition of FeOCI and FeSO₄⋅H₂O respectively.
(4) Both anhydrous FeSO₄ and FeCl₃ produced by these thermal decompositions have a hygroscopic character as known well.
The authors conclude from the results mentioned above that catalytic action due to the immersion of γ-Fe₂O₃ into mineral acid solutions relates to the accelerating action on dehydration of crystal water contained as crystal stabilizer into γ-Fe₂O₃.

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Dielectric properties of high permittivity ceramics were measured and the relation between the microstructure and the electrical property of these ceramics was discussed. The results obtained are summarized as follows.
(1) For the preparation of BaTiO₃-Bi₂(SnO₃)₃, BaTiO₃-Bi₂(ZrO₃)₃, BaTiO₃-NiSnO₃ and BaTiO₃-La₂O₃⋅3TiO₂, calcined BaTiO₃ powder or BaCO₃⋅TiO₂ equimolar mixture were used as raw materials. The dielectric property of the fired specimens prepared from the calcined BaTiO₃ powder was markedly different from that of ones prepared from the BaCO₃⋅TiO₂ mixture in spite of the same chemical compositions.
(2) It was found that the solid reaction was controlled by varying the calcinating condition of a part of raw materials.
(3) For the preparation of the ceramic dielectric materials with flat temperature dependency of permittivity, the coexistence of two or more phases is required. Two important schematic models about the distribution of phases were proposed.
(4) The measurement of the temperature characteristics of permittivity is one of useful techniques for the investigation of the solid reaction because it makes possible to know the temperature of the Curie peak of permittivity as the important information of the reaction.

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原子力平和利用として, 将来のわが国のエネルギー需給の面でも国民生活水準の向上の面でも重大な影響をもつ, 原子力発電の開発利用の現状と将来性について, 諸外国における動向を含めて説明したものである.

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