Microwave ultrasonic attenuation in topaz, beryl, and tourmaline

Abstract
Microwave ultrasonic attentuation measurements have been made on single crystals of topaz, beryl, and tourmaline, and all are found to exhibit very low losses. The room-temperature attenuation coefficients are consistent with the Akhiezer mechanism which arises from interactions between the ultrasonic wave and the thermal-phonon assembly.