Structure and Magnetic Properties of Mn-doped CoFe2O4 Nanoparticles Prepared by Solvothermal Route

Spinel Co1-xMnxFe2 O (4) (x = 0, 0.25, 0.5, 0.75 and 1.0) nanoparticles were synthesized by a solvothermal method using polyethylene glycol (PEG) as a surfactant. X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray absorption near edge structure (XANES) spectroscopy and vibrating sample magnetometer (VSM) techniques were used to characterize phase, morphology, valence states, and magnetic properties of the samples. XRD analysis showed single phase of spinel structure, and the decrease of lattice constant on the effective Mn substitution was investigated. The effect of the PEG on the spherical aggregates of Co1-xMnxFe2 O (4) nanoparticles was observed. The result of XANES spectra showed Mn2+/Mn3+, Fe3+, and Co2+ exist in the samples. The samples showed ferromagnetism at room temperature with a maximum saturated magnetization of 72 emu/g and the smallest coercivity of 45 Oe for x = 1.0. The origin of ferromagnetic behavior is believed to be due to the occupation of Mn2+/Mn3+ ions.