Mixtures of SiO₂ (amorphous), Mg(OH)₂ (brucite) and MgSiF₆⋅6H₂O corresponding to the compositions [Mg₆Si₄O₁₀E_x(OH)_8-x] of different x values were treated hydrothermally at temperatures from 270 to 1000°C, under water pressures ranging from 100 to 1000 atm.
The heat-treated samples were examined by an X-ray diffractometer and under a polarizing or electron microscopes.
Treatment of the sample with x=1.5 at temperatures below 500°C formed chrysotile in coexistence with minor quantity of sellaite and talc. Talc and chondrodite were found to be the main crystalline phases between 500° and 580°C and coexisted with cristobalite between about 600° and 800°C. Above about 830°C, chondrodite, cristobalite and minor quantity of unidentfied minerals were observed.
Treatment of the sample with x=3.0 at temperatures below about 400°C formed chrysotile, sellaite and minor quantity of unidentified minerals. At temperatures ranging from about 430 to 480°C, chondrodite was found to be a main crystalline phase and coexisted with crysotile, talc and minor quantity of unidentified minerals. Talc was formed, coexisting with chondrodite (or norbergite), cristobalite (or α-quartz) and minor quantity of unidentified minerals, at temperatures between about 500° and 800°C. Above about 900°C, chondrodite (or nordergite), cristobalite and minor quantity of unidentified minerals were obtained.
Treatment of the sample with x=6.0 at temperatures below 420°C formed sellaite in coexistence with minor quantity of talc and chrysotile. Talc, sellaite and minor quantity of unidentified minerals were obtained between about 450 and 650°C. At temperatures between about 700° and 800°C, talc was a main crystalline phase and coexisted with chondrodite, norbergite and unidentified minerals.
Treatment of the sample with x=8.0 at temperatures ranging from about 300 to 500°C formed sellaite in coexistence with minor quantity of chrysotile. Talc and sellaite, coexisted with cristobalite and chondrodite (?), were the main crystalline phases between about 550° and 800°C. Above about 850°C, cristobalite and norbergite were obtained.
In the specimen of x=12, that is, [Mg₆Si₄O₁₀F₁₂] composition, sellaite and cristobalite (or α-quartz) were found in the specimen treated at temperatures between about 250°C and 800°C.
Hydroxyl-chrysotile [Mg₆Si₄O₁₀(OH)₈] was an exception and any stability region of a single phase of fluor-hydroxyl chrysotile [Mg₆Si₄O₁₀F_x(OH)_8-x] did not exist, but fluorine ion in the specimen was inclined to react preferentially with magnesium ion to form sellaite.

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The thermal stability of the tetrahedral structures of the wurtzite and sphalerite types are discussed based upon crystal structural and physical data of AIN, BeO, ZnS and SiC
A consideration of ionic configuration energies of these compounds leads to a conclusion that the wurtzite type structure is stable at least in low temperature region for all of these binary compounds. On the other hand, if an account is taken on vibrational entropy, it is shown that the stable form at higher temperature tends to be of the sphalerite type, especially for those in which the difference of electronegativity of the component elements is less than around unity. Though the existence of the stable wurtzite type structure in high temperature region of some compounds like ZnS is not fully understandable, it is suggested that the occurrence may be explained in terms of the configurational energy and the vibrational entropy.

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The optical and paramagnetic resonance spectra have been obtained for divalent nickel ions in BaO⋅(5.1-1.5)B₂O₃, SrO⋅(3-1.5)B₂O₃ and CaO⋅(3-1.5)B₂O₃ glasses. The coordination about the nickel ion sites is found to be octahedral in all the glasses. Absorption bands due to tetrahedrally coordinated nickel ions are not observed. The crystal field splitting parameter 10 Dq decreases with the amount of alkaline earth contents in these three series of glasses, and also decreases in the sequence of CaO, SrO and BaO containing glasses if these alkaline earth contents are the same in each series of glasses. The value of the Racah parameter B and the spin-orbit coupling coefficient are both less than those values for free nickel ion. This fact is accounted for by introducing weak covalent Ni-O bonds. The covalency is found to become predominant in the order of BaO, SrO and CaO containing glasses.

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熱処理中に分相性硼珪酸ガラスの表面にしばしば異常な層ができ, この層は酸処理時に抵抗層となる. このことは, 高珪酸ガラス製造上で欠点となるので, この原因を解明するために, 著者らは硼珪酸ガラスの新鮮度, 人工風化時間, 炉雰囲気などを変えて, 熱処理時の表面層のでき具合を酸溶出の速さの測定および偏光解析法によって検討した.
溶出速度の測定結果から, 熔融直後のガラスを熱処理した場合および硼酸雰囲気中で熱処理した場合, 上記の異常表面層は全く生成しないこと, 古いガラスまたは人工風化時間が長いものを熱処理するほど, また炉の硼酸蒸気圧が低い雰囲気で熱処理されたものほど, ガラス表面の溶出速度が著しく遅くなっていることが明らかとなった. これらの結果から, 水と反応した表面ほど, 熱処理中に異常な表面層ができ易いことが判った.
偏光解析の結果から, 人工風化した表面は屈折率が低くなり, 表面に水和した層ができていることが明らかである. また風化時間が長くなるにつれて, 表面層の厚さが増大し, 1500Åに達する. これらの風化した表面を熱処理すると, 風化が進んだものほど屈析率がさらに小さくなり, 風化したものほど硼素とソーダが分相のための熱処理により揮発し易くなっていることを示している. また, 表面層の厚さは熱処理によってほとんど変らない. 風化が完全に進んだものを熱処理すると, その表面層の屈折率は1.45を示し, 翻素とソーダが完全に揮発してほとんど石英ガラスの組成になっていることが判る.

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Changes of lattice parameter, crystallite size and strain of two kinds of agate from Yamagatajuku, Ibaragi, Japan and Brazil were studied by an X-ray method. Crystallite size and strain perpendicular to (100) and (101) were computed by Warren's method of X-ray analysis after correcting for the instrumental broadening by Stokes' method.
The samples were heated at 300°C, 540°C, 600°C and 900°C for 24 hours. As concerns original agate, c-axis of agate was longer than that of rock crystal and axial ratio of agate corresponded to 1.002, which was larger than that of rock crystal, 1.100. As concerns agate heated higher than α-β inversion point, since a-axis of agate became longer than that of original agate and c-axis of agate became smaller than that of original agate, axial ratio became the same as that of rock crystal.
Crystallite size was evaluated to be 370Å and 300Å in the direction of ‹100› and ‹101› of Yamagatajuku agate. Crystallite size of Brazil agate was also evaluated to be 440Å and 390Å in the direction of ‹100› and ‹101›. Agate seemed to be elongated in the direction of a-axis. Crystallite size didn't change up to 900°C. Values of strain of agate were ranging from 0.004 to 0.001 and strain in the direction of a-axis increased when samples were heated. Yamagatajuku agate had smaller crystallite size and larger strain than Brazil agate.
Authors give computer program correcting for the instrumental broadening using Stokes' method.

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The phase diagram Al₂O₃-Al₄C₃ has been revised since Al₄O₄C and Al₂OC must be metastable phases. The eutectic of the system Al₂O₃-Al₄C₃ is to occur around 2012°C, while the eutectic reported by Foster et al. at 1840°C is of transient type observed on reducing Al₂O₃ into Al₄C₃ by C. The reduction path is not on the line Al₂O₃-Al₄C₃ in the Al-O-C ternary system.

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