Influence of La 3+ substitution on the structural, magnetic and electrical characteristics of Sr 2 FeTiO 6 double perovskites

In this study, the La 3+ ions are substituted at the Sr 2+ site in Sr 2 FeTiO 6 double perovskites using the solid state reaction method. The impact of La 3+ ion substitution on the Sr 2 FeTiO 6 physical characteristics have been studied. The SrTiO 3 structural parameters were utilised as starting model for performing the Rietveld refinement of powder X-ray diffraction patterns. Cubic symmetry with Pm3m space group was determined for the prepared materials. Due to the larger ionic radii of La 3+ ion, the La substituted samples showed slight increase in the lattice cell parameters leading to volume expansion. The La-substituted samples don’t exhibit any significant morphological differences when compared to parent compound. The diffused reflectance measurements also show no significant changes in the band gap values of La-substituted samples in comparison with the pure compound. The magnetization studies exhibit the enhanced ferromagnetic nature of La-substituted sample. Thermally activated charge carriers are also evident from the analysis of temperature dependent dielectric measurements.