Porous nanotubes of Co3O4:: Synthesis, characterization, and magnetic properties

Stoichiometric Co3O4 porous nanotubes have been synthesized through a simple modified microemulsion method. The structural and the chemical information of the as-grown nanotubes have been investigated by means of x-ray diffraction, electron microscopy, electron energy loss spectroscopy, and dynamic force microscopy. The results reveal that the as-grown materials are formed by concentric stacking of Co3O4 (111) planes or weaved porous nanotubes with diameters ranging from tens to similar to200 nm and sidewall thickness ranging from 2 to similar to20 nm. Magnetic property of the sample demonstrates a magnetic transition temperature at 8.4 K, indicating macroscopic quantum confinement effects from the sidewall thickness of the porous nanotube. (C) 2004 American Institute of Physics.