Model for Long ‐ Wavelength Optical‐Phonon Modes of Mixed Crystals

Abstract

Abstract A model is presented which describes the optical modes of a mixed crystal. The model emphasizes a realistic use of the local electric field and is completely defined by the macroscopic parameters of the pure end members. The concentration dependence of the optical frequencies can be categorized into four distinct classes in contrast to the usual two classes, “one‐mode” and “two‐mode”. We suggest that experimental evidence already exists which supports this new classification scheme.