Ferroelectric ternary solid solution of Pb(Mg1/3Nb2/3)O3–PbSnO3–PbTiO3 with morphotropic phase boundary

A ternary solid solution of Pb(Mg1/3Nb2/3)O3–PbSnO3–PbTiO3 (PMN–PSn–PT) has been synthesized in the form of ceramics by solid solution reaction and characterized by means of X-ray diffraction, dielectric spectroscopy, and ferroelectric measurements. The study on different oxidation states of tin shows that Sn2+ is the dominant valence state, thereby causing an impurity pyrochlore phase of the formula Sn2Nb2O7. A morphotropic phase boundary (MPB) region has been determined to exist at room temperature in the solid state ternary system. The compositions within the MPB region show the best piezoelectric properties in the system. For the ceramics of 0.42PMN–0.20PSn–0.38PT which are within the MPB composition range, the Curie temperature TC, piezoelectric coefficient and coercive field were found to be 165 °C, 345 pC/N and 7.0 kV/cm, respectively. Compared with the Pb(Mg1/3Nb2/3)O3–PbTiO3 system, the larger coercive field of PMN–PSn–PT would be attractive in high power sonar applications since it would allow larger bipolar fields to be used at a lower dc bias.