Synthesis and characterization of CoFe2O4–PVP nanocomposites

Abstract Cobalt ferrite–poly(N-vinyl-2-pyrrolidone) nanocomposites were prepared by drying a dispersion of cobalt ferrite (CoFe2O4) nanoparticles and poly(N-vinyl-2-pyrrolidone). Magnetic measurements indicate a superparamagnetic behavior. Zero-field-cooling magnetization experiments at 100 Oe show different trends depending on the CoFe2O4 nanoparticles size. For the smaller ones (3.9 nm), the blocking temperatures shift to lower temperatures with increasing concentration; however, this shift is not observed for the larger ones (6.6 nm). These differences can be related to the anisotropy constant of the CoFe2O4 nanoparticles and the interparticle dipolar interactions.