INFLUENCE OF THE DIFFERENT LOSS PARAMETERS ON PIEZOELECTRIC MATERIAL PERFORMANCES

Abstract Piezoelectric materials such as polymers (PVDF), copolymers (P(VDF-TrFE)), lead metaniobates or ceramic/polymer composites possess high losses. In this case, the characterisation method described in IEEE Standard on Piezoelectricity (1987) for low-loss materials is not applicable. Several methods have been proposed to determine the losses by introducing complex parameters in the piezoelectric constitutive equations. A number of these methods consider mechanical, dielectric and piezoelectric losses, but others only take into account mechanical and dielectric losses. In this paper, we investigate the influence of these types of losses on the electrical impedance of a thickness mode resonator. This study shows that piezoelectric losses have very little effect and that only dielectric and mechanical losses need to be taken into account for transducer design. Measurements were also performed on three different materials. The results using our method are compared to those of previously published studies.