Elucidating the Mn-Doping Induced Phase Transition from Orthorhombic Pnma to Rhombohedral R3c in LaFeO₃: Insights from Mossbauer Spectroscopy

LaFe1-xMnxO3 (0 <= x <= 0.9) samples were synthesized through the sol-gel method. According to X-ray diffraction (XRD) results, with the increase of Mn doping, the crystal structure of the sample changes from orthogonal Pnma structure to rhombohedral R3c structure, and a two-phase coexistence phenomenon exists within the range of 0.4 <= x <= 0.7. Using Mossbauer spectroscopy, the coexistence range of the two phases and the iron content in each phase were identified. At x=0.4, the Pnma phase contribution (91.1%) dominates, with only a slight R3c phase contribution (8.9%). As the amount of Mn doping gradually increases, the R3c phase becomes dominant at x=0.6 (74.6%), and the Pnma phase completely disappears at x=0.8. This work will provide an important perspective for future researchers studying similar phase coexistence systems.