Khatkevich's theory for acoustic axes in 6mm piezoelectric CdS

Abstract

Abstract. The simplest derivation of Khatkevich's equation based on Fedorov's mathematics is presented here in view of recent confusions on the subject discussed in the literature. In the development of Khatkevich's theory of acoustic axes the general equation is extended by introducing into consideration piezoelectric interaction. It is shown that the linear piezoelectric effect doubles the order of equation for the degenerated roots in hexagonal media in comparison with that obtained at taking into account pure elasticity only. Method is provided for control of phonon focusing anisotropy by investigation of acoustic axes in the piezoelectric medium. Examples of equilibrium dynamics of the acoustic axes for phonon modes in the temperature range from 4.2 to 500 K in CdS and of the phonon focusing factor in ZnO are supplied.