Ultrasonic Attenuation in Insulators at Room Temperature

Abstract

In many insulating crystals, the attenuation of sound waves of microwave frequencies is a result of energy transfer from the sound wave to thermal phonons. A simple correlation exists between sound attenuation in such crystals near room temperature and their thermal properties. This correlation is exhibited at 300°K for a number of crystals for which both sound attenuation and thermal measurements have been made. Crystals which have low sound attenuation at microwave frequencies and room temperature appear to be those with light mass atoms, high Debye temperatures, and complex crystal structures. Estimates are made of the sound attenuation to be expected at 300°K in two materials for which thermal data alone are available.