The complex piezoelectric response of relaxor ferroelectrics

The amplitude-dependent complex piezoelectric response of Pb(Mg _1/3Nb_2/3)O₃-PbTiO₃ (PMN-PT) relaxors has been investigated using a single-beam interferometric technique as a function of AC electrical drive, superimposed DC bias, and measurement frequency. Large-induced longitudinal piezoelectric coefficients (d₃₃) were observed over a wide DC bias range below polarization saturation. Investigations as a function of AC drive revealed the presence of strong nonlinearities, where the value of d₃₃ increased by 50% with increasing drive. In addition, large unexpected piezoelectric loss factors (Tanδ_(piezo)) were observed, in materials which where otherwise characterized by the lack of dielectric loss and anhysteretic behavior