Surface passivation and characterization of cobalt-ferrite nanoparticles

In the present study we report on the chemical synthesis, the surface passivation process, the peptization in low pH aqueous medium, and the characterization of cobalt-ferrite nanoparticles. The as produced, passivated and peptized cobalt-ferrite nanoparticles were investigated by atomic absorption measurements, transmission electron microscopy, and Mössbauer spectroscopy. The liquid Helium Mössbauer spectra consist of three well-defined sextets in all the studied samples. The data are discussed in terms of the characteristics of the nanoparticle surface layer and the effects produced by the passivation and peptization/aging processes.