Synthesis and characterizations of the (1∈-∈x)Pb(Sc _1/2Nb_1/2)O₃-xPbTiO₃ solid solution ceramics

We report a systematic study of the (1∈-∈x)Pb(Sc _1/2Nb_1/2)O₃-xPbTiO₃ (PSN-PT) solid solution in the form of ceramics with compositions at or near the morphotropic phase boundary (MPB) region (0.35∈≤∈x∈≤∈0.50). The PSN-PT ceramics have been synthesized by an improved two-step wolframite precursor method. The synthetic process has been optimized in terms of calcining and sintering conditions. Both dielectric permittivity measurements and differential scanning calorimetry (DSC) show a clear peak at T _C, at which the transition from the paraelectric to ferroelectric phase takes place. Interestingly, the solid solution of the MPB compositions displays a T _C∈>∈200 °C, i.e. higher than the T _C of the Pb(Mg_1/3Nb_2/3)O₃-PbTiO₃ and Pb(Zn_1/3Nb_2/3)O₃-PbTiO₃ solid solutions, making the PSN-PT system very promising piezoelectric and ferroelectric materials for high-temperature applications. A dielectric maximum as high as 50,000 is obtained for the 0.65PSN-0.35PT ceramic with losses smaller than 0.05. The values of the remnant polarization and the strain level of the PSN-PT ceramics are comparable to those of the PZT ceramics.