Cobalt superparamagnetic nanoparticles

Superparamagnetic nanoparticles can form chains even at zero field as has been demonstrated by simulations and by experiment in a dispersion of iron nanoparticles at zero field. Ring formation happens by unpaired dipoles at the ends of chains and have also been observed with 27 nm cobalt particles. External magnetic fields can by applied in order to orient flexible chains in one direction enabling formation of superstructures. 

FeCCOs- Sonolysis was also used in our group to prepare iron nanoparticles stabilized by polydimethylphenylene oxide (PPO). The particles were found to be superparamagnetic and to adopt, depending on their size, the a (bcc) or the 7 (fee) structure. This method was extended to other precursors such as Co(NO)(CO)3, recently used by Gedanken to produce cobalt particles. ... 

---