Interpretation of the Vibration Spectrum of Mix-Crystals

Abstract

The vibration frequencies of a linear chain of the type ...XZYZXZYZ... are calculated and discussed. The chain is considered to be a model for a mix-crystal of the components XZ and YZ. Only one vibration is strongly active enough to give a reflection band, its frequency being intermediate between those of the components, in agreement with observation. Another vibration, at lower frequencies, is very weak or inactive, depending on the exact nature of the mix-crystal structure—whether the ions X and Y are distributed regularly or statistically.