Anomalous piezoelectric and elastic properties of a tetragonal PZT ceramic near morphotropic phase boundary

A ceramic of nominal formula Pb0.95Sr0.05(Zr0.53Ti0.47)(0.98)Nb0.02O3 has been investigated. Dielectric properties and differential scanning calorimetry tests pointed to a transformation temperature of 306 degrees C. By means of a dynamic method the piezoelectric and complex elastic compliances for polarized ceramics have been measured as a function of temperature. The temperature dependence of the elastic properties has indicated bilinear coupling between the order parameter and strain. The unexpected existence of a pertinent piezoelectric response far above T epsilon(max). accompanied by strong changes in the elastic properties was observed. On the basis of the dielectric response and x-ray diffraction studies carried out on poled and unpoled ceramics, the influence of the compositional fluctuations and the existence of polar regions on the anomalous piezoelectric activity above T epsilon(max) were considered rather than a change of symmetry after the action of an external electric field.