Composition and orientation dependence of phase configuration and dielectric constant tunability in poled Pb(Mg1/3Nb2/3)O3–PbTiO3single crystals

The composition and orientation dependence of the room temperature piezoelectric constant d33 and the dielectric constant tunability was investigated in poled single crystals of (1− x)Pb(Mg1/3Nb2/3)O3–xPbTiO3 (PMN–PT) with x varying from 0.24 to 0.38. The temperature, frequency, orientation and composition dependence of the dielectric constant in the poled crystals shows that domain configurations and phase transitions in the poled crystals strongly depend on both composition and orientation. Poled polydomain crystals near the morphotropic phase boundary, especially for -poled 0.70PMN–0.30PT crystals with a critical composition for the relaxor state, possess a large piezoelectric constant d33 = 2210 pC N−1 and a high dielectric constant tunability of 40.6% (at a dc bias of 1 kV mm−1). The large tunability of er in PMN–PT crystals is expected to be the most promising candidate for potential applications in continuously adjustable capacitors and dielectric amplifiers.