xPb(In 1=2 Nb 1=2 )O 3 -yPb(Mg 1=3 Nb 2=3 )O 3 -zPbTiO 3 (xPIN-yPMN-zPT) ternary ceramics with morphotropic phase boundary (MPB) composition were synthesized by columbite precursor method. xPIN-yPMN-zPT phase diagram was investigated by x-ray diffraction and dielectric measurements. According to the results of dielectric measurements, the Curie temperatures (T c ) and rhombohedral to tetragonal phase transition temperature (T rÀt ) were found to be in the range of 173-212 C and 114-155 C, respectively, indicating that the T rÀt was increased with adding PIN component. In the MPB region, the highest T rÀt ¼ 155 C was found in 0.32PIN-0.38PMN-0.30PT ceramic, that greatly expanded temperature usage range.