Propagation behavior of love waves in a pre-stressed piezoelectric layered structure

It is well known that due to the mismatch of the material properties there exists residual stress during the manufacture process of piezoelectric surface acoustic wave devices. On the other hand, to prevent the piezoelectric material from fragile fracture, the piezoelectric layered structures are usually pre-stressed during the manufacture process. In order to enable the electric excitation of the Love waves, a piezoelectric material can be chosen as substrate of the layered structures. The propagation of Love wave in a layered piezoelectric half-space with initial stress is taken into account in this paper, where a thin elastic film as the guiding layer is in intimate contact with a piezoelectric substrate. The phase velocity equations of Love wave propagation are obtained for electrical open and shorted cases at the free surface, respectively. It is seen that the phase velocity of Love wave decreases and the electromechanical coupling factor increases remarkably as the absolute values of initial stress is greater than 100 MPa. The results obtained in this paper are meaningful for the design of high quality surface acoustic wave (SAW) devices in the microwave technology.