Effects of calcium on the phase transition and the dielectric properties of Sm-modified PbTiO₃ ceramics

(Pb_0.85Sm_0.1)(Ti_0.98Mn_0.02)O ₃ ceramics exhibits exceptionally large electromechnical anisotropy. Their properties allow them to be used for high-frequency applications such as SAW devices and piezoelectric transformers. Our previous studies on (Pb_0.88-xCa_xSm_0.02)(Ti_0.98Mn_{0.0 2})O₃(x = 0.11-0.17) ceramics demonstrated that the Ca and Sm additives not only reduce the lattice anisotropy, but also maintain good dielectric and anisotropic properties of Sm and Ca-modified PbTiO₃ ceramics. This study investigates the effect of calcium on the phase transition and dielectric properties of this system. X-ray diffraction, Raman scattering and DSC methods are used to elucidate the doping effect of (Pb_0.88-xCa_xSm_0.02)(Ti_0.98Mn_{0.0 2})O₃. The X-ray results show that the c/a ratio decreases as the amount of Ca dopant increases. The DSC result indicates that the transition temperature of the F-P transition of Ca-doped PbTiO₃ decreases as the content x increases.