Accurate determination of the compression curve of Ta to over 600 GPa

The aim of this proposal is to extend XRD measurements of Ta from 150 GPa to above 600 GPa under hydrostatic conditions, using a Ne pressure-transmitting medium in a toroidal DAC. These measurements will leverage our ability to compress metals in a Ne pressure-transmitting medium using a toroidal DAC up to the 600 GPa range, as well as the validation of Ne volume as a pressure gauge. This work aims to resolve the significant uncertainty in the compression curve of Ta in the multi-Mbar range, which has been the subject of few recent studies—the latest being ramp compression experiments up to 2 TPa. Additionally, Ta has been predicted by calculations to undergo an Electronic Topological Transition under pressure, which is expected to cause significant changes in its mechanical properties. Here, we expect to significantly reduce uncertainties to clearly observe the expected softening of the bulk modulus due to the ETT