Accurate determination of material constants of piezoelectric crystal from SAW velocity measurements

A nonlinear least-squares algorithm to determine the material constants of LiNbO₃ from primary SAW (surface acoustic wave) velocity measurements is shown. If the values of the mass density and the unclamped permittivities are known at least to some accuracy, all 13 independent elastic, piezoelectric, and dielectric constants are obtained with high precision. While measurements on Y-cut LiNbO ₃ do not provide enough information to perform this task, the SAW velocities on 128°-rot-Y-cut LiNbO₃ are sensitive to all material constants. This method is not restricted to LiNbO₃ only, but can be applied to other strong coupling materials (e.g. LiTaO₃) as well