Preparation and Characterization of Relaxor Ferroelectric 0.65Pb (Mg1/3Nb2/3)O-3-0.35PbTiO(3) by a Polymerizable Complex Method

A modified polymerizable complex (PC) method for the preparation of the relaxor ferroelectric 0.65Pb(Mg1/3Nb2/3)O-3-0.35PbTiO(3) (PMN-PT) ceramics has been developed using a novel water-soluble Nb precursor. The effects of Pb content and sintering temperature on the structure, morphology, composition, and electrical properties of PMN-PT powders and ceramics were investigated systematically. It was found that the modified PC method could effectively reduce the initial crystallization temperature of the perovskite phase to 500 degrees C. For PMN-PT samples with 15% excess Pb content sintered at 600 degrees C for 2 h, the 87% perovskite phase can be achieved, which is much higher than that in conventional solid-state reactions and other solution-based methods at the same temperature. On further increasing the sintering temperature to 1100 degrees C, the perovskite phase content basically remains constant. This is attributed to the Pb-deficient pyrochlore phase formation. On increasing the sintering temperature to 1250 degrees C, the dielectric constant and remnant polarization of PMN-PT ceramics significantly improved due to the larger grain sizes, enhanced density, and the decreasing pyrochlore phase. PMN-PT ceramics with a 98.5% content of the perovskite phase have been fabricated at 1250 degrees C. It displays typical ferroelectric relaxor characteristics with a remnant polarization of 18 mu C/cm(2), a coercive field of 9.6 kV/cm, a piezoelectric coefficient of d(33) = 360 pC/N, and room-temperature and maximum dielectric constants of 3600 and 10 500 at 1 kHz, respectively.