Influence of Ag on the Magnetic Anisotropy of Fe{sub 3}O{sub 4} Nanocomposites

In this work, the thermal decomposition method is used to obtain Fe{sub 3}O{sub 4}-Ag nanocomposites. The weight losses observed in the thermogravimetric measurements are used to estimate the amount of organic mass present in the samples. Fourier-transform infrared (FTIR) spectra show characteristic absorption peaks of the stretching vibration of the Fe-O and C-H groups. Samples are characterized structurally and morphologically by measurements of X-ray diffraction (XRD) and transmission electronic microscopy (TEM), respectively. The XRD patterns indicate the formation of a cubic phase with spinel crystallographic structure. Particles sizes analysis estimated by Scherrer’s equation for Fe{sub 3}O{sub 4} phase show that sizes are unaffected by the Ag-insertion. TEM images reveal that the nanoparticles have a spherical-like shape and a mean particles sizes ranging 3 < d < 4 nm. The best fits of zero-field-cooling and field-cooling (ZFC/FC) curves allow us to state that the magnetic anisotropy constant decreasing as a function of Ag concentration.