Solid solutions of the (1-x)Ba(Ti0.50Sn0.50)O3•xPbTiO3 system: Preparation, structural and dielectric characterization

Ceramic samples of the (1-x)Ba(Ti0.50Sn0.50)O-3 center dot xPbTiO(3) system with 0 <= x <= 1 were synthesized by solid-state reaction method. The samples were characterized by X-ray diffraction, dielectric measurements, and thermally stimulated depolarization currents (TSDCs) technique. It was established that the solid solutions with the perovskite structure were formed in the entire range of the compositions. The structure symmetry of the solid solutions changes from cubic (x <= 0.30) to tetragonal (x > 0.47) with increasing PbTiO3 content. The samples with 0.30 < x <= 0.47 contained mixtures of the tetragonal and cubic phases. The solid solutions exhibit a pronounced aging effect. This effect manifests itself as non-reproducible maxima in the temperature-dependent spectra of the dielectric permittivity epsilon(T,f) and losses tangent tan delta(T,f) measured around room temperature. The increase of the amount of PbTiO3 in the ceramic samples causes sequential changes of their dielectric response from that typical for relaxor ferroelectric for x = 0 - 0.3 to ferroelectric-like with a diffuse phase transition for x = 0.4 - similar to 0.8 and, finally, to usual ferroelectric response for x = similar to 0.8 -1. The compositions with 0.20 < x < 0.40 show coexistence of both ferroelectric and relaxor properties. The temperature dependences of the TSDCs show pronounced maxima at temperatures T approximate to T-C, T similar to 100 K and T similar to 300 K; the phenomena that are at the origin of the effects are discussed.