Investigations on structural and magnetic behavior of LaPrCo_1-xFe_xMnO₆ double perovskite system

Double perovskite system LaPrCo_1-xFe_xMnO₆; (x = 0.2, 0.5, 0.8, & 1.0) was synthesized by sol–gel method and its structural and magnetic properties were studied. XRD analysis followed by Rietveld refinement inveterate the phase formation without impurities and validated the co-existence of three phases; monoclinic (P2₁/n, ordered), orthorhombic, and rhombohedral (Pbnm & R3c, disordered). LPCFMO1 (x = 0.2) exhibited highest extent of ordering (monoclinic phase, 77.67%) of Co/Fe & Mn ions at alternate octahedral sites among all prepared compositions. The crystallite size (D) and strain (ε), both showed an irregular trend with increase in iron content, and maximum strain (8.24 × 10⁻³) is observed for LPCFMO1 (x = 0.2) sample. The overlapping of Electron density gradients for upper and lower bounds in 2-D maps revealed crystallographic symmetry. XPS study confirmed the coexistence of different oxidation states of B/B’-site transition metal cations (Co, Fe & Mn) in the prepared samples. BET analysis suggested that samples are mesoporous as pore size is >2 nm. LPCFMO1 is observed to have maximum magnetization (M_max) of 40.43 emu/g which decreases continuously with increase in iron content and takes value 21.55 emu/g for LPFMO (x = 1.0). Antiferromagnetic coupling among Fe³⁺ and Mn³⁺ ions is responsible for the continuous decrease in M_max with increase in iron content. The multi-domain structure of the prepared samples makes them suitable for memory device application.