Thermal Expansion and Pressure Effect on the Lattice Vibration of Tetrahedrally Covalent Compounds

Abstract

Using a phenomenological theory with the experimental pressure dependence of elastic stiffness constants and the linear interpolation formula for mode Grüneisen parameters, the thermal expansion and the pressure effect on the lattice dynamics are investigated for tetrahedrally covalent compounds. The observed data for the temperature-dependence of thermal expansion coefficients are reproduced by introducing only two parameters. One is the parameter for the transverse acoustical mode related to the negative thermal expansion at a low temperature, and the other is that for the optical mode related to the constant thermal expansion at a high temperature. Numerical calculations are performed for GaAs, GaSb, InSb, ZnSe and ZnTe, and the derived mode Grüneisen parameters give useful data on the experimental pressure dependence of phonon frequencies.