Transverse surface waves in a 6 mm piezoelectric material carrying a prestressed metal layer of finite thickness

The propagation of transverse surface waves in a piezoelectric material carrying a prestressed metal layer of finite thickness is investigated analytically. The dispersion equation is solved in closed form for class 6 mm piezoelectric materials and the conditions for the existence of various wave modes are obtained. Numerical examples are presented for an aluminum, gold, or zinc layer on a PZT-4 ceramic substrate. The presence of initial stress can extend or shorten the range of phase velocity within which a nonleaky but dispersive mode exists. The dependence of phase velocity on initial stress opens a new window for designing acoustic wave devices.