Thermal expansion of Earth minerals to mantle temperatures: benchmark data for ab initio and finite strain models

The chemistry, mineralogy and temperature of Earth’s interior are the most fundamental properties of our planet, but because direct access is limited we must infer them from seismological observations. This requires knowledge of the properties for Earth's minerals at mantle P&T. Unfortunately, experimental measurements are sparse, such that finite-strain extrapolations or ab-initio calculations are required. However, the accuracy of neither method is demonstrated, and no data to test these techniques exists. Here we will measure the thermal expansivity of forsterite and periclase (two abundant mantle minerals) to temperatures of the mantle adiabat. This will allow us to benchmark the accuracy of current approaches and build correction routines if required, to improve the accuracy of calcualtions and/or extrapolations.