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.