The pressure-volume-temperature equation of state of MgO derived from shock Hugoniot data and its application as a pressure scale

The pressure-volume-temperature (P-V-T) equation of state (EOS) of MgO is widely used as a pressure scale in static compression experiments. However, there are remarkable inconsistencies among different previously proposed MgO pressure scales. We calculated the P-V-T EOS of MgO up to 300 GPa and 3000 K based on experimental shock Hugoniot data and a simple thermal pressure model within the Mie-Gruneisen-type analysis framework. All of the parameters used can be measured experimentally with high accuracies. We found that, in overall, the calculated P-V-T EOS of MgO has excellent agreement with the available volume compression data over a wide range of pressure and temperature. A comparison of our results with the previous theoretical investigations has also been performed and confirms that our calculated P-V-T EOS of MgO can be used as a reliable pressure scale for static experiments at high pressures and high temperatures.