Investigation of structural, morphological, optical and electrical properties of double-doping Lanthanum ferrite

Polycrystalline compounds of La_0.75Ba_0.25−xSr_xFeO₃ containing different amounts of Sr (x = 0.00, 0.05, 0.10 and 0.15) were synthesized by the sol–gel method. The samples were characterized by means of X-ray diffraction (XRD), scanning electron microscope (SEM), FTIR and Raman spectroscopy, UV–Vis spectroscopy and I–V electrical measurements. XRD analysis reveals that all samples possess an orthorhombic structure with Pnma space group. The Lattice parameter values are found to decrease with the increase of Sr contents. The surface morphology and microstructure were analyzed using SEM images. It is found that all samples have similar microstructure morphology, but differ in the range of grain sizes. Raman spectroscopy measurements exhibit slight shift in Raman modes with Sr-doping. A shift of characteristic peaks for Fe–O bond in FTIR spectra were observed with the increase of Sr content. Using the Tauc plot methodology, the optical band gap values have been evaluated from the UV–Vis measurements. These values increase with Sr content. Finally, room temperature electrical resistivity decreases with Sr content increasing. The obtained results show that the structural, optical and electrical properties have low strongly affected by the strontium content.