Synthesis and characterization of size-controlled cobalt-ferrite-based ionic ferrofluids

Size-controlled synthesis of cobalt-ferrite nanoparticles, their passivation and peptization as stable ferrofluids are reported. Transmission electron microscopy and Mossbauer spectroscopy were used as characterization techniques. Particles with little change in size distribution, in the 10-15nm diameter ranges, were obtained using stirring speeds between 2700 and 8100 rpm. The anomalous diffusion has been used to explain the nanoparticle size-control mechanism. (C) 2001 Elsevier Science B.V. All rights reserved.