Langasite Family Crystals As Promising Materials For Microacoustic Devices At Cryogenic Temperatures

Using the pulse-echo ultrasonic technique, the velocities of the longitudinal and the shear bulk acoustic waves propagating in five crystallographic directions of LGS and SNGS single crystals were measured in a wide temperature range from 4.2 to 300 K. Elastic constants are derived and treated in the frame of Varshni approach. Some characteristic parameters of the theory are obtained. Strong piezoelectric excitation survives down to liquid helium temperature.