Optical and dielectric properties and lattice dynamics of some fluorite structure ionic crystals

Abstract

Some optical, dielectric and lattice properties of three alkaline earth fluorides (calcium, strontium and barium fluorides) and of two other isomorphous fluorides (cadmium and lead fluoride) are reported. Results obtained from experimental studies on infrared and Raman spectra give the fundamental transverse and longitudinal optical lattice mode frequencies, the two-phonon absorption spectra, and the spectra associated with U centre absorptions. Calculations of phonon dispersion curves, density of states and density of com­bined states functions, have been made for all five crystals and these are compared with the experimental results.