Synthesis and assembly of high-quality cobalt ferrite nanocrystals prepared by a modified sol-gel technique

Colloidal cobalt ferrite nanocrystals were produced using a new sol-gel-like synthesis based on the procedure developed by O'Brien et al. (J. Am. Chem. Soc. 123 (2001) 12085) for the synthesis of BaTiO3 nanocrystals. This synthesis involves the single-stage high-temperature hydrolysis of the metal alkoxide precursors to obtain crystalline, uniform, organically coated nanoparticles which are well-dispersed in an organic solvent. The particles could be further manipulated to form Langmuir-Blodgett films consisting of close-packed nanocrystal monolayers. The structural and magnetic properties of these nanocrystals indicate similarity to bulk CoFe₂O₄ with a very high coercivity at low temperatures.