Study of physical properties of cobalt oxide (Co3O4) nanocrystals

Cobalt oxide nanocrystals of size 10-15 nm have been prepared by a simple co-precipitation method. The structural investigations have been performed with X-ray diffraction and Transmission Electron Microscopy. Specific surface area of the nanocrystals is 77.5 x 10(4) cm(2)/g which have been calculated by X-ray diffraction data. Optical properties are discussed with UV/visible spectroscopy which shows the multiple band gap energies 2.28 eV (O-II -> Co-II) and 1.57 eV (O-II -> Co-III) which suggest the possibility of degeneracy of the valence band. The magnetic behavior is investigated using Vibrating Sample Magnetometer. The Co3O4 nanocrystals possess paramagnetic character at room temperature. (C) 2010 Elsevier Inc. All rights reserved.