Doping effect of antimony on BaFeO3 perovskite oxide: optical, electronic, magnetic and thermoelectric properties

Abstract

Perovskite oxides have attracted significant attention in contemporary research due to their tunable properties achieved through doping. The concerns of toxicity with lead (Pb)-doped perovskites highlight the need for environmentally friendlier alternatives such as antimony (Sb)-doped perovskites. In this study, the electronic, magnetic, structural, optical and thermoelectric properties of Sb-doped BaFeO₃ (BFO) are investigated using the full-potential linearized augmented plane wave (FP-LAPW) method based on density functional theory (DFT) in conjunction with the Boltzmann transport theory. The doping levels considered are x = 0.125 and 0.25 for the composition of BaFe_1−xSb_xO₃. The DFT simulations reveal that Sb doping on BFO causes a slight lattice distortion but retains the cubic structure (space group 221-Pmm), indicating the material's structural stability. The density of states at the Fermi level (E_F) increased with Sb doping, indicating an enhanced carrier concentration. The computed optical characteristics reveal that pure BFO has strong ultraviolet absorption. In contrast, BaFe_0.875Sb_0.125O₃ (12.5% Sb-doped BFO) and BaFe_0.75Sb_0.25O₃ (25% Sb-doped BFO) show a progressive reduction with Sb substitutional doping, accompanied by a significant drop in the extinction coefficient and dielectric constant. The plasma frequency decreased from 3.372 eV (pure BFO) to 1.0548 eV (25% Sb-doped), indicating a reduction in free-carrier activity and metallic characteristics. The computed figure of merit (ZT ≈ 0.50) shows significant enhancement after 25% Sb doping. In addition, this study highlights that Sb doping on BFO greatly improves the dual tunability of optical transparency and thermoelectric efficiency through substitutional doping.