Piezoelectric properties of bidomain LiNbO₃ crystals

Our studies of piezoelectric properties of bidomain ("head-to- head") Z-cut plates of LiNbO₃ formed by diffusion treatment show that the spectrum of excited vibrations differs from that of monodomain crystals. We found that the length- and width-longitudinal vibrations are suppressed and bending vibrations appear to be maximal for an inverted layer thickness equal to one-half of the sample thickness. The amplitude of the fundamental frequency and its overtones for the thickness vibrations depend on the thickness of the inverted layer. A model explaining these properties is proposed.