Substitution preference and dielectric properties of Y3+-doped Ba0.62Sr0.38TiO3 ceramics

Ba0.62Sr0.38TiO3 ceramics of perovskite structure are prepared by solid reaction method with addition of x mol% Y3+ and their dielectric properties are investigated systematically. It is found that, integrating with the lattice parameters and the distortion of crystal lattice, there is an alternation of substitution preference of Y3+ ion for the host cations in perovskite lattice. Owing to Y3+ ion entering the A site, the highest dielectric constant is 5300 for 0.5 mol%-Y3+-doped samples; when the Y3+ ion content is more than 0.5 mol%, Y3+ ion tends to occupy the B site in perovskite lattice, causing a drop of the dielectric constant. Owing to appearance of the oxygen vacancy and disappearance of the reduction of Ti4+ ion, the optimized dissipation factor is 0.0015 for 1.0 mol%-Y3+-doped samples, and the dissipation factor is very stable with the environment temperature increasing, making it a superior candidate material for applications. It is also found that the clear deviations from Curie–Weiss law can be seen in various yttrium-doping specimens, revealing the diffuse phase transition.