Electromechanical and elastic isotropy in the (011) plane of 0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 crystals: Inhomogeneous shearing of polarization

Temperature dependent electromechanical investigations of 〈110〉, 〈001〉, and 〈111〉 oriented morphotropic phase boundary compositions of Pb(Mg1/3Nb2/3)O3-PbTi03 crystals have been performed. Softening of the dielectric constant, piezoelectric constant, and Young’s modulus was found for all three orientations, near a ferroelectric rhombohedral to ferroelectric tetragonal transformation. However, the value of Young’s modulus was an order of magnitude higher along 〈111〉, than either 〈001〉 or 〈110〉. An unusual electromechanical and elastic equivalence was found between the 〈110〉 and 〈001〉 directions. This result demonstrates that the enhanced electromechanical performance of oriented piezocrystals is not constrained to the 〈001〉 orientation, but rather to the (011) plane.