Thermal behaviour of γ-anhydrite (γ-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 γ-anhydrite is anisotropic being larger along the c axis. Within the 343-383 K thermal range, γ-anhydrite has been found to partially re-hydrate to bassanite CaSO4 ·0.5H2O. At 455 K the transformation γ-CaSO4 → β-CaSO4, insoluble anhydrite, starts reaching completion at 653 K. © Springer-Verlag 2008.
The thermal behaviour of γ-CaSO4 / Ballirano, Paolo; Melis, Elisa. - In: PHYSICS AND CHEMISTRY OF MINERALS. - ISSN 0342-1791. - STAMPA. - 36:6(2009), pp. 319-327. [10.1007/s00269-008-0280-0]
The thermal behaviour of γ-CaSO4
BALLIRANO, Paolo;MELIS, ELISA
2009
Abstract
Thermal behaviour of γ-anhydrite (γ-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 γ-anhydrite is anisotropic being larger along the c axis. Within the 343-383 K thermal range, γ-anhydrite has been found to partially re-hydrate to bassanite CaSO4 ·0.5H2O. At 455 K the transformation γ-CaSO4 → β-CaSO4, insoluble anhydrite, starts reaching completion at 653 K. © Springer-Verlag 2008.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
