P-V-T equation of state of periclase from synchrotron radiation measurements

The volume of periclase (MgO) has been measured by monochromatic X-ray diff raction in a laser-heated diamond anvil cell up to a pressure of 53 GPa and a temperature of 2500 K. The X-ray source was synchrotron radiation at the European Synchrotron Radiation Facility (Grenoble, France). In addition to laser heating, the use of argon as a pressure transmitting medium provided quasi-hydrostatic conditions in the cell assembly. In order to take therma l pressure effect into account; pressure was measured using an internal pre ssure calibrant (platinum). By analysis of the experimental P-V-T data set the following parameters K-0(') = 3.94 +/- 0.2 when K-0 is fixed to of stat e);were obtained: at ambient temperature, KS, 161 GPa (with a Birch-Murnagh an equation alpha(P = 0, T) = (3.0 + 0.0012 T) x 10(-5) K-1; under,high tem perature, (partial derivative K-T/partial derivative T)p = -0.022(3) GPa K- 1. The quasi-harmonic Debye model appears to describe correctly the tempera ture dependence of the volume at high pressure within experimental errors, with the following parameters: theta(D0) = 800 K, gamma(0) = 1.45 (Gruneise n parameter under ambient conditions), and q = 0.8 +/- 0.5.