High-Pressure X-Ray Thermal Diffuse Scattering Measurements on Polycrystalline Samples for Elastic Moduli Determination

The in-situ determination of a material’s elastic tensor at high pressure is of the highest importance for numerous fields of research, namely materials science, condensed matter physics, and geophysics where it is the cornerstone of seismology. As it stands, no method exists to obtain this information from highly heterogeneous and opaque samples. In this innovative proposal, we aim to combine two new, but well-established and highly synergistic approaches—X-ray thermal diffuse scattering (TDS) and single-crystal X-ray diffraction of polycrystals (SC-XRDp)—that together enable the full elastic tensor determination of high-pressure high-temperature in-situ synthesized polycrystals, irrespectively of their transparency or chemical heterogeneity. This novel methodology will be demonstrated on: bridgmanite (MgSiO3) and two phases of Fe2O3, the perovskite and post-perovskite phases.