Cubic boron nitride as a primary calibrant for a high temperature pressure scale

Abstract

We present results establishing a new high pressure scale at high temperature based on the thermal equation of state and elastic properties of cubic boron nitride (cBN). This scale is derived from simultaneous measurements of density and sound velocities at high pressure and temperature independent of any previous pressure scale. The present results obtained at room temperature to 27 GPa suggest the validity of the current ruby scale (within±4% at 100 GPa). At high temperature, data obtained at 16 GPa to 723 K are in fair agreement with the thermal equation of state of cBN reported in our previous work. We have also shown that cBN can serve as a convenient pressure gauge in X-ray and optical studies using the laser heated diamond anvil cell.