57Fe Local Environment and Magnetic Properties of Chitosan Coated CoFe(2−)Sm O4 Nanoparticles

We report on the synthesis and characterization of single phase Sm doped Co-ferrites nanoparticles, CoFe(2-x)SmxO4 with x = {0.0, 0.05, 0.10, 0.15, 0.20}. The samples were characterized by X-ray diffraction, Mossbauer spectroscopy at 12 K and 300 K, transmission electron microscopy and vibrating sample magnetometry. The particle size, saturation magnetization and coercivity field are found to decrease with the increase of Sm3+ concentration. The particles had sizes from 5.6 nm to 9.5 nm. The cation distribution obtained by X-ray diffraction and mossbauer spectroscopy corresponds to a partially inverted ferrite. The magnetocrystalline anisotropy energy was determined from hysteresis curves. Since the samples are composed of superparamagnetic and thermally blocked nanoparticles, we used a combination of Langevin and hyperbolic tangent functions to fit the magnetization curves, the results were in close agreement with the experimental results.