Synthesis, characterization and magnetic properties of Co3O4 nanotubes

Well-aligned Co3O4 nanotubes were synthesized within the nanochannels of porous anodic alumina membranes using a single-source chemical vapor deposition method. Scanning electron microscopy and transmission electron microscopy showed that the Co3O4 nanotubes are highly ordered with uniform diameter in the range of 100-300 nm and length up to tens of microns. X-ray diffraction, the Raman spectrum, energy-dispersive spectroscopy and selected-area electron diffraction demonstrated that the nanotubes are composed of pure cubic phase polycrystalline Co3O4. Magnetic measurements using a SQUID magnetometer suggested the presence of a strong antiferromagnetic interaction with Weiss constant theta = -248 K. The real and imaginary parts of the ac susceptibility at f = 10 Hz had a maximum at 4.0 K, and the field dependence of the magnetization at 1.8 K showed a small hysteresis loop with a coercivity of similar to 98 Oe.