Temperature derivatives of elastic stiffness evaluated from the SAW delay-temperature behavior on lithium tantalate plates

The paper presents an accurate evaluation of the temperature derivatives of elastic stiffness of lithium tantalate on SAW delay-temperature dependence data. We use a nonlinear formalism to correct describing SAW propagation on X,Y-cuts of lithium tantalate plates subjected to homogeneous thermally-induced deformation. A least squares method is used to fit the temperature derivatives of the elastic constants of lithium tantalate to the measured SAW temperature coefficients of delay of the first order (TCD1). To decrease computation time, the perturbation procedure is employed. This allows us to fit optimally the constants of crystals in order to get the coincidence with experimental SAW delay-temperature data using only one iteration step. To measure the SAW temperature coefficients of delay we used a new high-sensitivity method. The measurement errors of TCDI are better than 0.15%. The sensitivity ofthe method is about 0.01%.