Effect of doping by Bi and Ca on ferroelectric properties and relaxor character in the (Ba1−xCax)1−3y/2BiyTiO3 solid solution

The temperature dependence of the real and imaginary parts of dielectric permittivity for (Ba_1?xCa_x)_1?3y/2Bi_yTiO₃ solid solution prepared using the solid-state reaction technique, suggests that the relaxor character in this solid solution depends strongly on the Bi than on the Ca doping percent.X-ray diffraction analysis show that Bi doping can be fully incorporated into the perovskite lattice of (Ba_1?xCa_x)TiO₃. Doping with Bi causes remarkable shift of the maximum of dielectric permittivity (T_m) at low temperatures and the evolution of ε′_r exhibiting strong frequency dispersion. For some compositions, we have observed a typical behavior of a well-known relaxors. On the other hand, we pointed out that the relaxor character is linked principally to the nature of the substituting element and not to the heterogeneity in general. So the Ca element does not have the same effect as the Bi one.