Ferroelastic Phase Transition in SrAl2Si2O8 Feldspar at Elevated Pressure

M. D. McGuinn and S. A. T. Redfern
Department of Geology, The University, Manchester, M13 9PL, United Kingdom.

Abstract: Synthetic end-member strontium feldspar (SrAl2Si2O8) has been studied in a diamond-anvil cell at elevated pressures up to 10.3 GPa using energy-dispersive X-ray powder diffraction. Cell parameters have been refined between ambient pressure and 6 GPa. SrAl2Si2O8 undergoes a ferroelastic phase transition from the ambient pressure monoclinic space group I2/c to the high-pressure triclinic space group I1¯ at 3.2 ± 0.4 GPa. The transition appears to be first-order and the ferroelastic and co-elastic components of the spontaneous strain tensor have been calculated.

Keywords: strontium • feldspar • ferroelasticity • phase transition • diamond-anvil cell

Mineralogical Magazine; March 1994 v. 58; no. 390; p. 21-26; DOI: 10.1180/minmag.1994.058.390.02
© 1994, The Mineralogical Society
Mineralogical Society (www.minersoc.org)