Top-seeded solution growth and characterization of rhombohedral PMN–30PT piezoelectric single crystals

Piezoelectric single crystals from 70Pb(Mg1/3Nb2/3)O3–30PbTiO3 solid solution were grown by a top-seeded solution growth method that prevented phase segregation and promoted (0 0 1) growth. Rhombohedral symmetry was confirmed by polarized light microscopy and the dielectric, piezo- and ferro-electric properties were characterized. A dispersive maximum of dielectric permittivity appears around TC = 125 °C, which slightly shifts towards higher temperatures with increasing frequency, indicating weak relaxor behaviour. Rhombohedral–tetragonal phase transition was detected at 105 °C. This temperature is higher than the depoling temperature of the morphotropic phase boundary compositions (50–80 °C), thus extending the upper limit of the application temperature for electromechanical transducers. The piezoelectric coefficient (d33) was found to be 1240 pC N−1, with a strain level reaching 0.12% at an electric field of 12 kV cm−1. The longitudinal electromechanical coupling factor k33 reaches 85%, which persists upon heating up to 100 °C.