Electric field dependence of dh in lead magnesium niobate-lead titanate ceramics

The hydrostatic piezoelectric coefficient d_h, in the 0.9PMN-0.1PT ferroelectric relaxor composition was studied as a function of the electric bias field at 500 Hz using a laser interferometer. It was found that d_h approaches a very large value of ~300 pC/N and then saturates at an electric bias field of ~3.5 kV/cm. The voltage coefficient and the sensitivity were also found to be comparable to and larger than, respectively, those in lead zirconate-titanate (PZT) ceramics despite a high dielectric constant in the relaxor material. Unlike the d₃₃ and d₃₁ piezoelectric coefficients, d_h did not, under the experimental conditions, depend on electric bias field in a manner predicted by the phenomenological theory