Influence of temperature on structural, magnetic and thermal properties of superparamagnetic MnFe2O4 nanoparticles

Abstract Magnetic nanocrystalline MnFe2O4 nanoparticles with spinel structure were synthesized using co-precipitation technique and the effect of annealing temperature on physicochemical properties were studied using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Vibrating sample magnetometer (VSM), and Thermogravimetric analysis (TGA). XRD confirmed the formation of single-phase cubic spinel structures with crystallite sizes ranging from 11.45 to 16.05 nm. FTIR revealed the formation of spinel ferrite nanoparticles with oleic acid binding. TGA demonstrated the formation of pure MnFe2O4 nanoparticles with improved crystalline structure at 300 °C, which developed secondary phases on annealing at 500 °C followed by cation redistribution at tetrahedral and octahedral sites at 700 °C. The heat treatment decreased the saturation magnetization from 15.85 emu/g to 14.30 emu/g which eventually increased to 14.83 emu/g. All the prepared nanoparticles showed superparamagnetic behavior. The results obtained from all the analyses support each other.