| MgO-Al2O3-SiO2系统的某些玻璃的结晶研究Ⅰ.堇青石的新变体和假蓝宝石的生成特点 |
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| 引用本文： | 沈步明
,郑学正
,李达周.MgO-Al2O3-SiO2系统的某些玻璃的结晶研究Ⅰ.堇青石的新变体和假蓝宝石的生成特点[J].地质科学,1974,9(2):171-181. |
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| 作者姓名： | 沈步明 郑学正 李达周 |
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| 摘 要： | 堇青石是MgO-Al2O3-SiO2系统中的一个不一致熔融三元化合物,堇青石的多晶转变和有序-无序的结构变化一直是许多学者感兴趣的问题,并且作了比较深入的研究。
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| 关 键 词： | , |
STUDIES ON THE CRYSTALLIZATION OF SOME GLASSES IN THE SYSTEM MgO-Al2O3-SiO2 I. A NEW METASTABLE PHASE OF CORDIERITE AND THE CHARACTERISTIC IN FORMATIONOF SAPPHIRINE |
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| SHEN BU-MING,ZHENG XUE-ZHENG,LI DA-ZHOU.STUDIES ON THE CRYSTALLIZATION OF SOME GLASSES IN THE SYSTEM MgO-Al2O3-SiO2 I. A NEW METASTABLE PHASE OF CORDIERITE AND THE CHARACTERISTIC IN FORMATIONOF SAPPHIRINE[J].Chinese Journal of Geology,1974,9(2):171-181. |
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| Authors: | SHEN BU-MING ZHENG XUE-ZHENG LI DA-ZHOU |
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| Abstract: | A β-cristobalite-like phase is found in the system, MgO-Al2O3-SiO2 containing small amount of CaO and TiO2 at 1 atm. The powder diffraction patterns of the new phase have the same β-cristobalite patterns. However, its refractive indexes are 1.540-1.545, higher than those of β-cristobalite (N = 1.486), and its dimenson a0 is 7.099A, slightly greater than 7.031-7.044A as presented by synthetic β-cristobalite. The β-cristobalite-like phase first appears in some heating glasses at 950℃ transforms mostly into cordierite with distortion index △ = 0 at 1280℃, and finally disappears entirely at 1340℃. The experimental results suggest that the β-cristobalite-like phase probably is a new metastable phase of cordierite, and is the β-cristobalite solid solution.During the devitrification of some glasses, the sapphirine occurs in the temperature range from 1180℃ to 1450℃, which is at least 150℃ degrees lower than the temperature in the equilibrium condition. Under the supercooling condition, the phase crystallization field of sapphirine expands remarkably. Therefore, the supercooling crystallization in the nonequilibrium condition to some extent can be regarded as the partial pressure. |
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