Structural and vibrational analysis of LaFe_1-xMn_xO₃(x = 0.05, 0.10, 0.15 and 0.20) perovskite materials

Lanthanum orthoferrite (LaFeO3) and lanthanum manganite (LaMnO3) are the important family of perovskite compound which intensively studied and explored due to its applications as functional materials, such as a fuel cell electrode, photocatalytic and gas sensor. The performance of functional materials is strongly depended on their structural properties. Here, we investigated the structure and vibrational of LaFe1-xMnxO3 (x = 0.05, 0.10, 0.15 and 0.20) perovskite materials prepared by sol-gel method. The structural and optical properties of the materials were characterized by X-Ray diffraction (XRD) spectroscopy, Fourier Transform Infra-red (FTIR) spectroscopy, Raman spectroscopy, and Ultraviolet-Visible (UV-Vis) spectroscopy. The analysis of the XRD pattern confirmed the single-phase orthorhombic structure (space group: Pnma) following by the decreasing of lattice parameters, crystallite size, and Fe/Mn - O bond distance with the increasing of Mn-content. The presence of the Fe/Mn -O -Fe/Mn bending and Fe/Mn -O stretching modes has been confirmed by FTIR and Raman investigation. The optical band gap energy was measured by UV-Vis DRS spectroscopy, which obtained in the range of 1.99-2.14 eV. The band gap energy decreases with the increase of Mn-content.