Unusual superparamagnetic behavior in bulk Ba0.198La0.784Ti0.096Fe0.8O3-δ

We report the observation of superparamgnetic behavior induced by the substitution La³⁺ by Ba²⁺ at A-sites and Fe⁺³ by Ti⁴⁺ at B-sites. Ba_0.198La_0.784Ti_0.096Fe_0.8O₃-_δ was synthesized via solid state reaction. The Rietveld refinements revealed an orthorhombic (Pbnm). The low-mag STEM results showed that the particles were found to exhibit square like shape and formed in single crystal with high degree of crystallinity. The particle size ranges of 50−300 nm. Element mapping demonstrates a complementary distribution between Ba and La, while homogenous distribution is found for Fe and O. The optical band gap determined from UV–vis analysis is equal to 1.93 eV which is smaller than the reported one for LaFeO₃ and BaTiO₃. The hysteresis loops at 300 K and 10 K show superparamagnetic behavior, which deviate extremely from the antiferromagnetic nature of LaFeO₃ perovskite. The temperature dependent magnetization demonstrates that the material kept a net magnetization of 12.29 (emu/g) at very low temperature.