Structural distortion facilitated magnetic and ferroelectric ordering in Ba-doped SrFeO3−δ

Abstract

This study explores the synthesis and structural transformation of Ba-doped SrFeO_3−δ exhibiting interesting electronic and magnetic properties. These samples with the general formula Sr_1 − xBa_xFeO_3−δ (x = 0, 0.1, 0.15, 0.2) were prepared using the citrate auto-combustion method. X-ray diffraction analysis, complemented by Rietveld refinement, confirmed the formation of single-phase cubic structure with space group Pm-3 m for the undoped sample. However, the introduction of larger-radii Ba²⁺ ions caused lattice distortion, leading to symmetry reduction into the P1 space group. The impact of Ba doping on grain size evolution was further examined using field emission scanning electron microscopy (FESEM), and energy-dispersive X-ray spectroscopy (EDS). The stretching vibrational mode of Fe-O at 600 cm⁻¹ supported the presence of an octahedral coordination. Room-temperature Mössbauer spectroscopy provided insights into the Fe⁴⁺/Fe³⁺ ratio and corroborated the structural transformation. Among the synthesized samples, Sr_0.8Ba_0.2FeO_3−δ demonstrated the highest magnetization (M_s=1.102 emu/g, M_r=0.026 emu/g) and enhanced ferroelectric properties (0.1 µC/cm²). These findings highlight the inherent flexibility of its perovskite structure, allowing for precise tuning and optimization of its functional properties.