Characterization of electromechanical coupling coefficients of piezoelectric films using composite resonators

By analysing the resonance frequency spectrum of a composite resonator cons isting of a piezoelectric ceramic film deposited on a substrate plate, the thickness extensional mode electromechanical coupling coefficient of the fi lm, k(t)(2), can be directly calculated from the effective coupling factor values, k(eff)(2), for two special modes of the resonator. The effects of t he mechanical loss in the piezoelectric films on the measurement are invest igated by numerical simulation, and some guidelines for improving the accur acy of the k(t)(2) measurement are reported.