Theoretical study of pseudo SAW in a half-space of piezoelectric crystals

Pseudo surface acoustic wave (PSAW) in piezoelectric substrates is theoretically investigated. Following phenomena are analyzed: (1) in the supersonic region where 3 partial waves are of bulk nature, some PSAWs consist of only 2 growing components, (2) in the subsonic region where no partial wave is of bulk nature, a solution exists when including 1 growing component and allowing a decay along the surface, (3) some cuts can support 2 true SAW solutions of similar polarization. It yields that the number and nature of SAW solutions depend on both the crystal orientation and the partial waves composition, and that the known SAW existence and uniqueness theorem does not apply to an arbitrarily anisotropic piezoelectric material. Currently used criteria for constructing the PSAW solution will be reviewed, their validity conditions discussed.