Velocity measurements of microwave ultrasonic waves in quartz

The velocities of microwave ultrasonic waves at 9.2 GHz have been measured using pulse-echo techniques in X-cut and Z-cut quartz rods. In the X-cut quartz, the longitudinal mode velocity was (5.71±0.05)×105 cm/sec and the transverse mode velocities were (5.20±0.05)×105 cm/sec. The longitudinal velocity for the Z-cut quartz was (6.33±0.03)×105 cm/sec. In contrast with the measurements of Ogawa and Sakamoto these results agree with the low—frequency velocities reported by McSkimin [J. Acoust. Soc. Am. 34, 1271 (1962)].