Pressure calibration of diamond anvil Raman gauge to 310GPa

Abstract

In order to develop an optical method for pressure determination in the multimegabar region, the first-order Raman spectra of diamond anvils were investigated at pressures up to $310\mathrm{GPa}$ . The high-frequency edge of the Raman band, which corresponds to the Raman shift of the anvil culet due to the normal stress, was calibrated against the sample pressure derived from the equation of state of Pt. The obtained pressure dependence of the edge frequency demonstrates the reliability of this diamond anvil Raman gauge. Up to the maximum pressure of this study, the relation between Raman frequency and normal stress at the diamond anvil culet is formally similar to the equation of state of a hydrostatically compressed isotropic elastic body having a bulk modulus of $K_0=547\left(11\right)\mathrm{GPa}$ and a pressure derivative of the bulk modulus $K_0{}^{\prime }=3.75\left(20\right)$ .