Vibrational and Raman Spectroscopic Study of Cubic Boron Nitride Under Pressure Using Density Functional Theory

Abstract

Pressure-dependent mechanical, vibrational and Raman spectroscopic study of the cubic boron nitride in context of recent experimental Raman spectroscopic has been performed using theab initio calculations based on density functional theory. Detailed analysis of the pressure-dependent mechanical and phonon properties shows that the pressure significantly affects the elastic constants and phonon frequencies. There is a systematic variation of elastic properties with pressure while a polynomial expression is used to fit the pressure dependence of the Raman shift. The longitudinal optical–transverse optical (LO-TO) splitting reduces with pressure, and the intensity of both LO and TO peaks start diminishing after 750 GPa. The phonon dispersion curves up to 1000 GPa indicate its dynamical stability. The lower slope of frequency versus pressure for the LO and TO modes at higher pressures suggests its use for pressure calibration at higher pressures.