Extrinsic coefficient charcterisation of PZT ceramics near the morphotropic phase boundary

Abstract

PZT ceramics with high piezoelectric coefficients have high extrinsic contributions. This extrinsic behaviour, which is related to the domain wall movement, produces high non-linear effects that are sometimes inconvenient, for example when it increases the losses in power devices. The relation between extrinsic behaviour and non-linearities could be used to provide a good extrinsic characterization of materials in order to optimise the piezoelectric devices. In all cases the physical explanation of the behaviour is sought. The aim of this work is to study the dependence of the linear and non-linear dielectric, piezoelectric and mechanical coefficients on the Ti fraction in PZT ceramic compositions near the morphotropic phase boundary (MPB). The dependence of these coefficients on the defect concentration is also analysed. Hard ceramics belonging to Ferroperm Piezoceramics, with two different acceptor dopant levels, high and low, have been measured.