The thermal behaviour of γ-CaSO4

被引:18
|
作者
Ballirano, Paolo [1 ]
Melis, Elisa [1 ]
机构
[1] Univ Roma La Sapienza, Dipartimento Sci Terra, I-00185 Rome, Italy
关键词
Soluble anhydrite; gamma-Anhydrite; gamma-CaSO4; Thermal behaviour; X-ray powder diffraction; Rietveld method; CALCIUM-SULFATE HEMIHYDRATE; X-RAY-DIFFRACTION; RIETVELD REFINEMENT; GYPSUM DEHYDRATION; TEMPERATURE-RANGE; CRYSTAL-STRUCTURE; ANHYDRITE CASO4; PHASE; TRANSFORMATION; BASSANITE;
D O I
10.1007/s00269-008-0280-0
中图分类号
T [工业技术];
学科分类号
08 ;
摘要
Thermal behaviour of gamma-anhydrite (gamma-CaSO4, soluble anhydrite) has been investigated in situ real-time using laboratory parallel-beam X-ray powder diffraction data. Thermal expansion has been analysed from 303 to 569 K with temperature steps of 4 K. Lattice parameters and volume were fitted with a second-order polynomial to calculate thermal expansion coefficients. Thermal expansion of gamma-anhydrite is anisotropic being larger along the c axis. Within the 343-383 K thermal range, gamma-anhydrite has been found to partially re-hydrate to bassanite CaSO4 center dot 0.5H(2)O. At 455 K the transformation gamma-CaSO4 -> beta-CaSO4, insoluble anhydrite, starts reaching completion at 653 K.
引用
收藏
页码:319 / 327
页数:9
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