Langasite: what temperature coefficients of material constants are correct?

The paper presents an evaluation of the temperature coefficients of elastic constants of langasite on both BAW and SAW delay-temperature dependence data. Least squares method is used to fit the temperature coefficients of the elastic constants of langasite to the measured BAW and SAW temperature coefficients of delay of the first order (TCDI). For sufficient decrease of computation time, the perturbation procedure is employed. That allows us to fit optimally the constants of crystals in order to get the coincidence with experimental BAW and SAW delay-temperature data using only 1 iteration step in a computer.