Nonlinear strain and DC bias induced piezoelectric behaviour of electrostrictive lead magnesium niobate-lead titanate ceramics under high electric fields

Laser Doppler interferometry has been used to determine the strain and piezoelectric response of Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT) electrostrictive ceramics as a function of electric fields up to 4?MV?m-1, frequencies between 0.1?Hz and 2.5?kHz and DC bias fields up to 3?MV?m-1. The strain and polarization of PMN-15 with a composition of 0.9PMN-0.1PT and PMN-38 with a composition of 0.85PMN-0.15PT both produced by TRS ceramics, have been measured at room temperature. The strain and polarization responses of PMN-15 ceramics under an electric field up to 4?MV?m-1 have been fitted to a polynomial model. The results suggest that a quadratic dependence of strain on polarization is not valid for large electric fields and that higher-order terms must be included. Our measurements showed that the effective piezoelectric coefficient, d33, of PMN-15 ceramics had a maximum value of 800?pm?V-1 at a bias field of 0.67?MV?m-1 and had little frequency dependence in the frequency range from 1?Hz up to 2.5?kHz. PMN-38 ceramic showed a maximum d33 of 1200?pm?V-1 at a bias field of 0.43?MV?m-1 and the d33 of this material showed a clear frequency dependence from 1?Hz up to 2.5?kHz.