Nonlinear dielectric behavior of piezoelectric ceramics

From the analysis of the models that can be used to describe phenomenologically the high signal dielectric behavior of PZT ceramics, a more complete model has been developed to avoid the difficulties of the previous models. It is assumed that the non-linear electrical displacement D_NL can be split into distinct terms that depend not only on the field, but also on the amplitude explicitly. The functions attached to the nondissipative part can be described as a function of some material dependent powers of the instantaneous field and of the amplitude of the field. By comparing all these terms in some piezoceramics, the losses term and the term which depend only on the amplitude of the field are very significant in soft rather than in hard materials. Some of the relations found in the dielectric behavior are also seen in the piezoelectric and elastic behavior, suggesting that they have the same origin, undoubtedly related to the non 180° domain wall motion