Temperature dependence of elastic, piezoelectric and dielectric properties of La3Ga5SiO14 and La3Ga5.5Ta0.5O14: An application of resonant ultrasound spectroscopy

The electromechanical properties of langasite, La₃Ga₅SiO₁₄, and langatate, La₃Ga_5.5Ta_0.5O₁₄, have been studied at elevated temperatures using resonant ultrasound spectroscopy (RUS). Furthermore, the coefficients of thermal expansion, the dielectric constants and their temperature derivatives, and the temperature evolution of the specific conductivity were investigated employing standard methods. At temperatures above about 550 K both compounds show strong ultrasonic at tenuation phenomena at frequencies below 1 MHz which are correlated with a rising electric conductivity.