Effects of Sr dopant and electric field poling on structural, thermal and dielectric properties of Ba1-xSrxTiO3 ceramics (x=0, 0.3, 0.4 and 0.45)

The behavior of Ba1-xSrxTiO3 ceramics (x = 0, 0.3, 0.4 and 0.45) in both unpoled and poled states was studied using XRD, SEM, DSC and dielectric methods. The ceramics exhibit pure perovskite structure with tetragonal symmetry for x = 0, 0.3 and 0.4 and pseudocubic for x = 0.45. It was found that the substitution of SrTiO3 to BaTiO3 significantly influences the properties under investigation, leading to a shift of phase transitions and weakness of the dielectric and ferroelectric properties. This suggests that the effects are mainly due to the differences in ionic size between dopant and host ions and to the more covalent nature of the A-O bond following Sr2+ addition and that the former effect is predominant. It was shown that prior electric field poling decreases the disorder introduced by Sr modification through reinforced domains/polar regions ordering.