The nonlinear, complex, induced-piezoelectric response of Pb(Mg1/3Nb2/3)O-3-PbTiO3 relaxors

The amplitude-dependent complex piezoelectric response of Pb(Mg1/3Nb2/3)O-3-PbTiO3 relaxors has been investigated using a single-beam interferometric technique as a function of ac electrical drive, superimposed de electrical bias, and measurement frequency. Large-induced longitudinal piezoelectric coefficients (d(33)) were observed over a wide de bias range below polarization saturation. On approaching polarization saturation, the value of d(33) decreased, approaching values typical of poled piezoelectric ceramics. Investigations as a function of ac drive revealed the presence of strong nonlinearities, where the value of d(33) increased with increasing drive. The nonlinear contribution was found to be on the order of 50% of the total response. In addition, large unexpected piezoelectric loss factors tan delta((piezo)) were observed in materials which were otherwise characterized by anhysteresis in the polarization electric field behavior. The value of tan delta((piezo)) was found to be in the range between 0.10 and 0.20, depending on various measurement conditions. With either increasing de bias or ac drive, the value of tan delta((piezo)) was found to decrease significantly. (C) 1996 American Institute of Physics.