Synthesis and characterization of surfactant and silica-coated cobalt ferrite nanoparticles

In this paper we report the synthesis and the characterization of ferrofluids constituted by cobalt-ferrite nanoparticles obtained from two different synthetic pathways: microemulsions and supersaturated solutions. Microemulsion technology leads to the formation of surfactant-coated magnetic nanoparticles, while dispersions of nanoparticles stabilized by their surface charges has been obtained by precipitating cobalt-ferrite from a supersaturated solution. The synthesis of a shell of silica on top of these nanoparticles is also reported. Surfactant coated nanoparticles have been characterized by means of UV-Vis absorption spectroscopy and trasmission electron microscopy (TEM), while nanoparticles obtained by supersaturated solutions have been studied by means of small-angle X-ray scattering (SAXS). (C) 2004 Elsevier B.V. All rights reserved.