In this paper, Piezoelectric properties of PMN-PZT ceramics were investigated as a function of CeO2 addition from 0mole % to 2.0 mole %. The grain size was decreased and the shape of it was more uniform with the addition of CeO2. At the specimen with 0.25 mole % CeO2, mechanical quality factor(Q(m)) and electromechanical coupling coefficient (K-p) showed the excellent results of 1,792 and 0.518, respectively. The electric coercive field was increased and the curie temperature was decreased with the addition of CeO2. A Rosen type-piezoelectric transformer has been designed and fabricated using composition ceramic material added with 0.5 mole CeO2. Voltage step-up ratios of 230 and 13 were obtained with the 42 x 8 x 1 mm transformer at no load, 100 K Omega resistance, respectively. Resonant frequencies of the transformer were also 81.4 KHz and 80 KHz at no load, 100 K Omega.
