Structure and physical property correlation in magnesium doped LaFeO3 nano perovskites synthesized by the green method

Abstract

Abstract In this work, La 1 − x MgₓFeO₃ (0.0 ≤ x ≤ 0.20) perovskite nanoparticles were successfully synthesized using a green synthesis route assisted by Moringa oleifera leaf extract. The influence of Mg²⁺ substitution on the structural, dielectric, and magnetic properties of LaFeO₃ was systematically investigated. X-ray diffraction and Rietveld refinement revealed a clear phase transition from cubic (Pm-3 m) to orthorhombic (Pnma) symmetry at x ≥ 0.17. Low Mg doping (x = 0.05, 0.10) induced a slight lattice expansion due to oxygen vacancy formation and Fe³⁺ → Fe²⁺ reduction, while higher doping levels led to lattice contraction from ionic size mismatch and structural distortion. Dielectric measurements demonstrated a significant enhancement in dielectric constant and suppression of dielectric loss up to x = 0.15, attributed to improved interfacial polarization and defect-induced conduction. Magnetic analysis via Vibrating Sample Magnetometer (VSM) and electron spin resonance (ESR) confirmed a transition from weak ferromagnetic to strong ferromagnetic behavior with increased Mg content, peaking at x = 0.17 due to enhanced Fe³⁺/Fe⁴⁺ exchange interactions and surface spin effects. These findings highlight the potential of Mg-doped LaFeO₃ nanoparticles for multifunctional applications in energy storage, sensing, and spintronic devices, while emphasizing the environmental and economic advantages of green synthesis approaches.