SH-Mode Piezoelectric Surface Waves on Rotated Cuts

If the sagittal plane of a piezoelectric surface wave is normal to a twefold axis of symmetry, the boundary condi- tion equations and the wave equations will decouple into two subsets. One subset pertains to an elastic Rayleigh wave, and the other pertains to an SH-mode piezoelectric surface wave. This is a necessary but insufficient condition for the existence of the SH-mode. Ths condition requires that the surface be parallel to the two-fold axis of symmetry, but its orientation is not otherwise constrained. Consequently, the orientation of the surface has a rotational degree of freedom about the axis of symmetry. In general, the SH-mode will only exist for a limited range of such angular orientations. The value of the smallest decay constant is a useful index of this range of existence. This article uses this index to report the range of surface orientations which are capable of sustaining the SH- mode on quartz, bismuth germanium oxide, Rochelle salt, ADP, barium sodium niobate, LiGa02, LiS04 H2 0, and NiS04 . 6H20.