Microstructures and physical properties of sol–gel derived Ba2FeMnO6 double perovskite

Abstract We report microstructures and physical (dielectric, magnetic, and optical) properties of sol–gel derived Ba 2 FeMnO 6 (BFMO) double perovskite powders. The BFMO powders belong to hexagonal crystal structure with P ‐6 m 2 space group. SEM images reveal the powders are nearly homogeneous distribution with spherical morphology and average particle size of 300 nm. Energy‐dispersive spectra gave out the molar ratio of the Ba:Fe:Mn elements equal to 2.16:1.00:1.00. FTIR spectrum verified the [FeO 6 ] and [MnO 6 ] octahedra present in the powders. X‐ray photoelectron spectroscopy spectra identified the chemical valence states of the constituent elements. The BFMO ceramics displayed a strong frequency dispersion dielectric behavior. A relaxor‐like dielectric behavior appeared around ∼475 K due to the contributions of oxygen vacancies of and the defect dipoles. A ferrimagnetic behavior was observed in the powders at 5 K with M S = 0.14 μ B /f.u. and H C = 1.51 kOe. The magnetic Curie temperature ( T C ) was 381 K, whereas the Neel temperature ( T N ) was 31 K. The ferrimagnetic behavior is governed by the Mn 3+ –Fe 4+ double‐exchange interaction via the mediated oxygen between them. The BFMO powders have a direct optical bandgap of 1.65 eV, which originates from the electron transferring from O 2p to Mn 3d (and/or Fe 3d) levels. The unique combination of high temperature ferrimagnetism and semiconductivity in the BFMO powders makes them particularly appealing for magnetic spintronics and photovoltaics.