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

Crystalline Sm 2 Ni 2 O 5 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 Sm 3+ –O–Sm 3+ framework; antiferromagnetic (AFM) ordering at T N = 9 K from Ni 2+ –O–Ni 2+ interactions; and a ferromagnetic (FM) transition at T C = 43.6 K associated with Ni 2+ –O–Ni 3+ 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.