Determination of phase transitions and equations of state of core materials at multi-megabar pressures

The goal of this proposal is to produce high-quality equation of state (EOS) of core materials at inner core conditions. In order to produce reliable density measurements at high pressure and temperature, evaluation of different pressure scales is critical part of the measurement. Here we propose to critically evaluate the consistency of the Pt, Au, MgO, NaCl, W, and Re pressure scales up to at least 450 GPa at room temperature, and further examine the thermal pressure up to at least 365 GPa and 3500 K, using our newly optimized toroidal diamond anvils. The data will be evaluated in conjunction with recent dynamic compression data to terapascal pressure. We will then investigate the effect of Si and C on the EOS of iron and possible formation of new compounds up to 365 GPa and 3500 K.