Rhombohedral-tetragonal ferroelectric structural phase transition temperature (T(R-T)), far below the Curie temperature (T,) in lead magnesium niobate-lead titanate (PMN-PT) relaxor ferroelectric single crystal, heavily restricts its further applications either as a sensor or transducer. To overcome this shortcoming, lead zirconate (PZ) was introduced into the PMN-PT pseudo-binary system to increase T(R-T) via the morphotropic phase boundary (MPB) composition design and optimization. According to the PMN-PT-PZ pseudo-ternary phase diagram, various compositions have been selected to discuss the relations between their phase structural transition and piezoelectric properties in the PMN-PT-PZ pseudo-ternary system. X-ray diffraction (XRD) investigation indicates clearly that PMN-PT-PZ ceramics with MPB compositions experience a typical structural phase transition process from rhombohedral phase to tetragonal phase. Remnant polarization (P(r)=33.4 mu C/cm(2)) and piezoelectric coefficient (d(33)=1050 pC/N) were obtained at the (0 0 1) cut PMN-PT-PZ single crystal. T(R-T) was increased up to 120 C by measuring its dependence of dielectric constant on temperature. (C) 2010 Elsevier B.V. All rights reserved.