Structural, morphological, thermodynamic, and magnetic properties of Sm₂Ni₂O₅: influence of co-precipitation vs sol-gel synthesis

Crystalline Sm₂Ni₂O₅ nanoparticles (SNONPs) were synthesized via Co-precipitation and Sol-gel methods to examine how synthesis influences structural, morphological, thermodynamic, and magnetic properties. XRD confirmed both samples crystallized into an orthorhombic Ima 2 structure after annealing at 800 °C for 6 h. SEM showed compact, smooth particles for Co-precipitated samples and brittle, fragmented ones for Sol-gel samples. EDS verified all expected elements with slight oxygen variation. Specific heat (0–300 K, 0.5 T) revealed distinct phase transitions: a 6 K anomaly indicating spin freezing in the Sm³⁺–O–Sm³⁺ framework; antiferromagnetic (AFM) ordering at T_N = 9 K from Ni²⁺–O–Ni²⁺ interactions; and a ferromagnetic (FM) transition at T_C = 43.6 K associated with Ni²⁺–O–Ni³⁺ sublattices. Above T_C, a paramagnetic (PM) phase emerged. The synthesis methods significantly affect crystallinity, governing magnetic and thermodynamic activities emphasizing SNONPs promise for spintronic and low-temperature magnetic applications.