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.