UERN

A.C. Lima, M.A. Morales, J.H. Araújo, J.M. Soares, D.M.A. Melo, A.S. Carriço. Evaluation of (BH)max and magnetic anisotropy of cobalt ferrite nanoparticles synthesized in gelatin.

Publicado em 02.08.2015 às 18:25:37

Abstract CoFe2O4 nanoparticles were synthesized using gelatin as a polymerizing agent. Structural, morphological and magnetic properties of samples treated at different temperatures were investigated by X-ray diffraction, scanning electron microscopy, Mössbauer spectroscopy and magnetization measurements. Our results revealed that the samples annealed at 623 K and temperatures above 973 K have a cation distributions given by (Co0.19Fe0.81)[Co0.81Fe1.19]O4 and (Co0.06Fe0.94)[Co0.94Fe1.06]O4, respectively. The particle sizes varied from 73 to 296 nm and the magnetocrystalline anisotropy, K1, has values ranging from 2.60×106 to 2.71×106 J/m3, as determined from the law of approach to saturation applied to the M×H data at high field. At 5 K, the saturation magnetization, coercive field and (BH)max varied from 76 to 95 Am2/kg, 479.9 to 278.5 kA/m and 9.7 to 20.9 kJ/m3, respectively. The reported values are in good agreement with near-stoichiometric cobalt ferrite samples.

Keywords Gelatin; CoFe2O4; Mössbauer spectroscopy; Magnetic properties; Nanoparticles; Anisotropy constant