Electronic Structure Studies Of The Spinel Cofe(2)O(4) By X-Ray Photoelectron Spectroscopy

The spinel CoFe(2)O(4) has been synthesized by combustion reaction technique. X-ray photoelectron spectroscopy shows that samples are near-stoichiometric, and that the specimen surface both in the powder and bulk sample is most typically represented by the formula (Co(0.4)Fe(0.6))[Co(0.6)Fe(1.4)]O(4), where cations in parentheses occupy tetrahedral sites and those within square brackets in octahedral sites. The results demonstrate that most of the iron ions are trivalent, but some Fe(2+) may be present in the powder sample. The Co 2p(3/2) peak in powder sample composed three peaks with relative intensity of 45%, 40% and 15%, attributes to Co(2+) in octahedral sites, tetrahedral sites and Co(3+) in octahedral sites. The O 1s spectrum of the bulk sample is composed of two peaks: the main lattice peak at 529.90 eV, and a component at 531.53 eV, which is believed to be intrinsic to the sample surface. However, the vanishing of the O 1s shoulder peak of the powder specimen shows significant signs of decomposition. (C) 2008 Elsevier B. V. All rights reserved.