Elastic Surface Waves on Free Surface and Metallized Surface of CdS, ZnO, and PZT-4

Abstract

Velocities, particle displacement, and piezoelectric field associated with surface elastic waves in CdS, ZnO, and lead-titanate zirconate (PZT-4) have been computed for two cases, with and without metallic coating on the surface. Compiled are data for CdS, ZnO, with their c axis normal to the surface, and PZT-4, poled in the direction normal to the surface. The velocity of propagation is found to be slightly lowered by the presence of metallic coating. Such change in velocity is applied to conduct an experiment which shows strong Bragg's reflection of elastic surface waves by metallic thin-film gratings. It has been pointed out that the previously reported surface wave velocities inferred from the response of interdigital transducer are believed to be slightly lower than the actual velocity of propagation.