Low-temperature elastic properties of Sr$_3$NbGa$_3$Si$_2$O$_{14}$ single crystals

The elastic properties of new piezoelectric Sr$_3$NbGa$_3$Si$_2$O$_{14}$ crystals of the langasite (lanthanum gallium silicate) family have been investigated. The temperature dependences of the elastic constants $C_{11}$, $C_{33}$, $C_{66}$, and $C_{44}$ have been measured in a wide temperature range from 300 to 4.2 K. The characteristic parameters of the crystal associated with the Einstein temperature and the Grüneisen parameter have been estimated at cryogenic temperatures. It has been shown that the piezoelectric activity of the crystal remains almost unchanged with a decrease in temperature from 300 to 4.2 K.