Acoustic Modes at the Twist Boundary in Piezoelectric Crystals

The transformations of the shear (SH and SV) and longitudinal (L) acoustic waves at the twist boundary in piezoelectrics of ̅62 m and ̅42 m the and classes have been investigated. This boundary is formed at a hard contact between two identical crystal half-spaces rotated relative to each other around the Z ||̅6||̅4 axis by an angle 2ϕ. Propagation occurs along the bisector of this angle ( х axis) in the ( x , y ) twist plane. Situations have been established in which the shear modes are localized at the twist boundary exclusively due to the combination of the piezoelectric effect and half-space rotation, as well as the joint effect of the elastic anisotropy and rotation. The cases of independence of a bulk wave of the half-space rotation and occurrence of leaky waves are described.