Elastic, piezoelectric, and dielectric properties of lanthanum-gallium tantalate crystals at temperatures of 20-600 degree C

Measurements of the temperature variations in the relative dielectric constants $$ \varepsilon_{33} theta /{\varepsilon_0} $$ , $$ \varepsilon_{11} theta /{\varepsilon_0} $$ ,and $$ \varepsilon_{22} theta /\varepsilon {}_0 $$ , conductivities g sub(11), g sub(22), and g sub(33), elastic constants $$ C_{11} Delta $$ , $$ C_{66} Delta $$ , and $$ S_{22} eta $$ , and electromechanical coupling constants k sub(t), k sub(26), and k sub(12) of lanthanum-gallium tantalate over temperatures of 20-600 degree C are reported. Data are presented on the effect of lifetime (breakdown) testing on these characteristics of the piezoelectric crystals after retention at a temperature of 625 degree C for 250 h.