Composition and electrical properties characterization of a 5” diameter PIN-PMN-PT single crystal by the modified Bridgman method

A Pb(In_1/2Nb_1/2)O₃–Pb(Mg_1/3Nb_2/3)O₃–PbTiO₃ relaxor ferroelectric single crystal with a 5” diameter and 145 mm length was grown by the modified Bridgman method. The composition distribution of the crystal boule was investigated. The result showed that the PbTiO₃ contents increased along the growth direction, which means that compositional segregation existed, and the effective segregation coefficient was simulated to be 0.84, which is close to that of 3” single crystal. The horizontal composition distribution in the crystal demonstrated that the solid-melt interface of the 5” single crystal was serious convex during crystal growth and was caused by the nonuniform radial thermal field of the large melt. The dielectric, piezoelectric, ferroelectric properties and domain structures were measured to investigate the effect of the composition change along the crystal growth direction. Based on the domain structure and electrical performance, the crystal boule was divided into rhombohedral, morphotropic phase boundary and tetragonal regions. It was found that the optimal piezoelectric coefficient d₃₃ of the 5” single crystal was more than 2000 pC/N. This work provided positive information for large sized single crystal growth of a relaxor ferroelectric single crystal.