Constraining mineral-physics models of planetary interiors using high-pressure-high-temperature Brillouin scattering measurements

Simultaneous measurements of acoustic wave velocities and densities of minerals relevant to the Earth’s and other planetary interiors are essential for interpreting seismic observations in terms of possible mineral compositions present at depth. Such combined measurements provide internally consistent data that are independent of external pressure calibrations and can therefore be extrapolated more accurately to conditions that are not yet reachable in the laboratory. However, such measurements at elevated pressures and temperatures are still challenging, especially when using in-house facilities. Here, we present acoustic wave velocities collected for garnet and ringwoodite single crystals with compositions relevant to the Martian mantle, using a Brillouin scattering system coupled with an X-ray diffractometer and a CO₂ laser heating setup.