A series of relaxor piezoelectric single crystals, including lead magnesium niobate-lead titanate (PMN-PT) and pure and manganese-doped lead indium niobate-lead magnesium niobate-lead titanate (PIN-PMN-PT and Mn: PIN-PMN-PT), have been developed by a modified Bridgman crystal growth process. These single crystals have been grown along both 〈001〉 and 〈110〉 with diameters up to 75mm. PIN-PMN-PT possesses the similar electromechanical properties to PMN-PT, while rhombohedral-to-tetragonal phase transition temperature (Trt) and coercive field (EC) increased to higher than 120° C and 4.5kV/cm, respectively. By doping with Mn, mechanical quality factor (QM) increased above 700 in 〈001〉-poled longitudinal mode without compromising electromechanical coupling (k 33), Trt and EC. This work demonstrated that by composition modification, the electromechanical properties of PMN-PT based crystals can be stabilized with respect to operating temperature and electric field.