In situ total strain measurements revealing the strain mechanism of Pb(Mg1/3Nb2/3)O3PbTiO3 single crystals

The strain behavior of 0.71 Pb(Mg1/3Nb2/3)O3-0.29 PbTiO3 (PMN-PT) single crystal prepared by a solid-state single crystal growth method was investigated on two most widely used orientations, i.e., (001)- and (011)-oriented. A special emphasis was put on the correlation among longitudinal and transverse strains and the consequent volume change. We show that seemingly different strain behavior of (001)- and (011)-oriented crystals has the same origin, and the underlying mechanism excludes possible contribution from the frequently cited polarization rotation. In situ monitoring of electric field induced Poisson’s ratio further suggested that the polarization vectors contributing to the strain properties in PMN-PT are not confined to a unique direction forced by the crystallographic symmetry but possess a span of angular range.