Jean C. Piquette
S. E. Forsythe
Underwater Sound Reference Detachment, Naval Res. Lab., P.O. Box 568337, Orlando, FL 32856-8337
Lead magnesium niobate (PMN) and lead magnesium niobate--lead titanate (PMNPT) are electrostrictive ceramics that exhibit high strains when a sample is subjected to a high voltage. The strain as a function of voltage is an almost perfect square-law over a large range of voltages, neglecting saturation and hysteresis. Unlike piezoelectric ceramics, these materials will not accept a significant permanent polarization, so the behavior cannot be linearized in this way. A transduction model of these materials based on an analogy to the Hunt electrostatic transducer is presented. The Hunt model is generalized for radiation loading and for a passive dielectric material between the plates. The dielectric model includes saturation but excludes hysteresis. The model is inverted analytically to determine a driving-voltage waveform which permits a PMN(PT)-based transducer to be driven at high voltage in a harmonic- and transient-free manner. Successful experimental applications of the model to measurements obtained from PMN(PT) samples are presented. The results include a description of a successful attempt to drive a PMN(PT) sample in a harmonic- and transient-suppressed manner at high voltage.