Electrical properties and phase of BaTiO3–SrTiO3 solid solution

It has been known that ABO3 type perovskite ferroelectrics, such as BaTiO3 (BTO) and SrTiO3 (STO), form a complete solid solution. In this study, Ba1−xSrxTiO3 (BST, x=0.0–1.0) solid solution were sintered by a solid-state reaction method using BTO and STO raw powders with appropriate chemical composition. The crystal structure was investigated by a Rietveld refinement method; Fullprof, using X-ray diffraction data. Within the reasonable goodness of fit, tetragonal symmetry was found in BST with x≤0.2, while BST with x≥0.4 were found to be cubic symmetry. However, Ba0.7Sr0.3TiO3 was difficult to decide whether it is cubic or tetragonal because of large uncertainties after final fitting. The composition ratios calculated from the fitted occupancies match well with those measured by EDS within experimental uncertainties. Remnant polarizations of BST with x<0.3 decrease with increasing Sr concentration. Furthermore, measured phase transition temperatures and maximum dielectric constant decrease as increasing Sr concentration. Measured electrical properties of BST were match well with the structural refinement investigations.