High-pressure phase transformation in CaSO4

被引：19

作者：

Chen, CC ^{[1
]}

Liu, LG ^{[1
]}

Lin, CC ^{[1
]}

Yang, YJ ^{[1
]}

机构：

[1] Acad Sinica, Inst Earth Sci, Taipei 115, Taiwan

来源：

JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS | 2001年 / 62卷 / 07期

关键词：

high pressure; X-ray diffraction; Raman spectroscopy; phase transitions;

D O I：

10.1016/S0022-3697(01)00023-3

中图分类号：

O6 [化学];

学科分类号：

0703 ;

摘要：

Raman spectroscopic study of anhydrite (CaSO4) at P > 140 kbar (after being heated to similar to 1000 degreesC by laser irradiation, and then cooled to room temperature) revealed that anhydrite transformed to a new high-pressure modification. Depending on the rate of pressure release, the high-pressure modification can only be partially preserved at ambient condition, if the pressure is slowly released. X-ray diffraction study of the partially preserved high-pressure modification at ambient condition revealed 15 diffraction lines for the new phase. The d-spacings for these new lines can be reasonably fitted by an orthorhombic cell with a = 6.602 +/- 0.005, b = 7.759 +/- 0.007, c = 5.970 +/- 0.007 Angstrom. If Z = 4 is assumed, the calculated volume of the new phase is 0.2% greater than that of anhydrite at ambient condition. The fitting is non-unique, however. The new phase has also been fitted by other possible candidate structures, such as sheelite, monazite and barite, but without success. (C) 2001 Elsevier Science Ltd. All rights reserved.

引用

页码：1293 / 1298

页数：6

共 9 条

[1] SIMPLIFIED SYSTEMATICS OF THE COMPOUNDS ABX4 (X=O2-,F-) AND POSSIBLE EVOLUTION OF THEIR CRYSTAL-STRUCTURES UNDER PRESSURE [J].