Role of Bismuth and Strontium A-Site Dopants on the Structural Evolution of Sol-Gel Derived Barium Titanate

Abstract

In this study, the doping of barium titanate was done by bismuth and strontium individually. The aim of the work was to emphasise the structural modifications that occur as a result of the incorporation of the dopants into the system of barium titanate. Sol-gel was the method of synthesis for the materials. The chemical formula used was \({\text{B}}{{{\text{a}}}_{{1 - x}}}{{{\text{Y}}}_{x}}{\text{Ti}}{{{\text{O}}}_{3}}\), where Y represents the two dopants bismuth and strontium and x was varied as 0, 0.05, 0.075, 0.10, and 0.15. The thermogravimetric analysis (TGA) curve, along with its first order derivative curve, indicated that the formation of the material and the stabilisation of the phase was around 900°C. Doping of barium titanate resulted in certain structural distortions, which have been discussed in terms of the defects introduced by the dopants in the system of barium titanate, the impact of their ionic radii on its crystal structure, and the varying values of the tolerance factor. These structural distortions were also experimentally supported by the X-ray diffraction (XRD) data obtained. Factors such as the ionic radii and oxidation state of the two dopants favour that when both are individually added to barium titanate, they are more inclined towards the A-site of the ABO₃ perovskite structure of barium titanate.