The complex piezoelectric response of relaxor ferroelectrics

The amplitude-dependent complex piezoelectric response of Pb(Mg/sub 1/3/Nb/sub 2/3/)O/sub 3/-PbTiO/sub 3/ (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 (d/sub 33/) 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 d/sub 33/ increased by 50% with increasing drive. In addition, large unexpected piezoelectric loss factors (Tan/spl delta//sub (piezo)/) were observed, in materials which where otherwise characterized by the lack of dielectric loss and anhysteretic behavior.