Structural and optical properties of Mg-substituted LaFeO3 nanoparticles prepared by a sol-gel method

•Mg-substituted LaFeO3 modified lattice distortion in the orthorhombic structure.•Mg substation decreased the optical band gap energy dramatically (2.13 to 1.29 eV).•Mg substitution improved the number of oxygen vacancy and created Fe2+/Fe4+ states. In this paper, we investigated the effect of Mg substitution on the Fe-site of perovskite-type LaFeO3 on its structural and optical properties at room temperature. Single-phase nanoparticles of LaFe1−xMgxO3 (x = 0.0, 0.1, 0.2 and 0.3) were synthesized using the sol-gel method. Refinement results from XRD spectra confirmed the orthorhombic crystal structure with Pnma space group. The transmission electron microscopy (TEM) images showed nanoparticles in the range of 40–130 nm. A significant effect of substitution on structural properties was clearly observed by the increasing lattice structure and distortion. This was also confirmed by Raman scattering and Fourier transform infrared spectroscopy by the upward shift of symmetric stretching of Fe/MgO6 octahedral vibration modes. The ultraviolet–visible analysis revealed a decrease in the bandgap energy with an increase in the Mg content. In addition, the valence state of surface elements was examined using X-ray photoelectron spectroscopy, which confirmed that the introduction of Mg ions into the lattice improved the oxygen vacancy concentration and created Fe2+/Fe4+ states. In addition, it was determined that Mg ions did not affect the La ion valence state.