Comparison between the Au and MgO pressure calibration standards at high temperature

Abstract

We compare the MgO pressure scales previously developed using molecular dynamics simulations based on empirical and non-empirical interatomic potentials, to check the accuracy of the reported pressure scales at high temperatures. We find excellent agreement between the two independent pressure scales over wide temperature and pressure ranges, with simulated pressure discrepancies between the two for specified relative volumes being within 0.5 GPa in the temperature and pressure ranges up to 2000 K and 30 GPa. Based on recent simultaneous pressure measurements using both the MgO and Au scales with a multi-anvil apparatus at 1873 K, we then compare the resulting pressures based on the MgO scale with those based on the Anderson's Au scale, which is recently widely used to estimate pressures in high temperature and high pressure experiments. We find the Andrerson's Au scale underestimates pressures by 1.4 ± 0.3 GPa relative to the MgO scale at 1873 K.