Optical Properties of Alkaline-Earth Chalcogenides. I. Single Crystal Growth and Infrared Reflection Spectra Due to Optical Phonons

Abstract

Single crystals of alkaline-earth chalcogenides, CaS, CaSe, SrS, SrSe, BaS and BaSe, have been prepared by the floating-zone method using a Xe-arc image furnace. Details of the crystal growth technique are described. As the first report of our studies on the optical properties of these IIa-VIb compounds, the infrared reflection spectra due to the optical phonons are presented. From a dispersion analysis of the spectra, the frequencies of transverse and longitudinal optical phonons and related dispersion parameters are determined. Discussions are made on the effective charges and the chemical trend of these binary compounds.