SYNTHETIC MGAL2O4 (SPINEL) AT HIGH-PRESSURE CONDITIONS (0.0001-30 GPA): A SYNCHROTRON X-RAY POWDER DIFFRACTION STUDY

Abstract

The equation of state and the structural behavior of synthetic MgAI2O4 have been investigated using synchrotron X-ray powder diffraction data collected to 30 GPa at room temperature. The Birch-Murnaghan, Vinet, and Poirier-Tarantola models have been fitted to the observed P-V data. The Birch-Murnaghan equation of state, with VO fixed at its experimental value, yields KO = 190.8(± 1.2) GPa, KO = 6.77(± 0.15) and KO =-0.075 GPa-1 (implied value). The compression of spinel occurs with a negligible change of the fractional coordinate of oxygen. Therefore the structural shrinking is a function of cell edge shortening alone. The results presented here are compared with those from the literature.