MgO, Au, and Pt Pressure Scales at High Temperatures

Abstract

We previously developed MgO, Au, and Pt pressure scales at high temperatures, without relying on any pressure scale. The MgO scale was obtained by MD simulations using semi-empirical potential models derived from the observed data of MgO at 0 GPa, including the volume thermal expansion, the temperature dependence of bulk modulus, and the elastic constants and their temperature and pressure derivatives. On the other hand, the Au and Pt scales were both derived using the Mie-Gruneisen-Debye type treatment based on the combined use of the observed data from shock compression, volume thermal expansion at 0 GPa, and temperature dependence of bulk modulus at 0 GPa from ultrasonic measurements. Based on simultaneous volume measurements of Au and MgO, Pt and MgO, and Au and Pt, previously reported using synchrotron X-ray diffractions at high temperatures and high pressures, it is found that our MgO, Au, and Pt scales are mutually very consistent over wide temperature and pressure ranges.