The anisotropy of the basic characteristics of Lamb waves in a (001)-Bi12SiO20 piezoelectric crystal

The orientation dependences of the phase velocity, the effective electromechanical coupling coefficient, and the angle between the wave normal and the energy flux vector are numerically calculated for zeroand first-order Lamb waves propagating in the (001) basal plane of a Bi12SiO20 cubic piezoelectric crystal. It is shown that the anisotropies of these modes are different and depend on the plate thickness h and the wavelength lambda. For h/lambda < 1, the mode anisotropy can exceed the anisotropy of the corresponding characteristics of surface acoustic waves propagating in the same plane; for h/lambda > 1, it approximately coincides with the SAW anisotropy for all the characteristics.