Spectroscopic mode Grüneisen parameters for diamond

Abstract

Room temperature measurements are reported of the first and second order Raman spectra of diamond in the hydrostatic pressure range 0-2.4 GPa. Values calculated from the data for the optic mode Grüneisen parameters have been fitted in terms of a simple lattice dynamical model for diamond involving volume dependent interatomic forces. The interpolated set of mode Grüneisen parameters are shown to be in substantial agreement with thermodynamic data. The simple model for the anharmonicity of the interatomic forces in the diamond group materials is shown to provide a qualitative explanation for the contrasting low temperature behaviour of the thermal expansion exhibited by these materials.