High temperature stability of surfactant capped CoFe2O4 nanoparticles

We investigate the effect of adsorbed surfactant on the structural stability of CoFe2O4 nanoparticles during vacuum thermal annealing. In-situ high temperature X-ray diffraction studies show a reduction of oleic acid coated CoFe2O4 nanoparticles into α-Fe and CoO under annealing at 800 °C. On the contrary, the uncoated CoFe2O4 nanoparticles remains stable, with its cubic phase intact, even at 1000 °C. Thermo-gravimetric analysis coupled mass spectra reveals that the evolved carbon from the surfactant aids the removal of oxygen atom from CoFe2O4 lattice thereby reducing it to α-Fe and CoO phases. These results are important in tailoring stable CoFe2O4 nanostructures for various applications.