Raman spectrum of cubic boron nitride at high pressure and temperature

Raman scattering experiments on cubic boron nitride were performed at simultaneous high-pressure and high-temperature conditions up to 21 GPa and from 300 to 723 K. Neon served as a (quasi)hydrostatic pressure medium. The frequency shift of the TO mode (1054 cm(-1) at 1 atm and 300 K) is found to be a coupled function of pressure and temperature. Different fits, using either a polynomial form or a Gruneisen model, are presented. The Raman data are used to derive values for the isothermal bulk modulus at ambient and high temperatures. The application of this compound as a high-pressure calibrant at high temperatures is also discussed.