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

Piezoelectric single crystals from 70Pb(Mg1/3Nb2/3)O-3-30PbTiO(3) solid solution were grown by a top-seeded solution growth method that prevented phase segregation and promoted (001) 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 T-C = 125 degrees C, which slightly shifts towards higher temperatures with increasing frequency, indicating weak relaxor behaviour. Rhombohedral-tetragonal phase transition was detected at 105 degrees C. This temperature is higher than the depoling temperature of the morphotropic phase boundary compositions (50-80 degrees C), thus extending the upper limit of the application temperature for electromechanical transducers. The piezoelectric coefficient (d(33)) 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 k(33) reaches 85%, which persists upon heating up to 100 degrees C. (c) 2007 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.