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The Valence Electronic Structure of Co3O4: Is It a Charge-Transfer Insulator?

Published online by Cambridge University Press:  16 February 2011

M.A. Langell ,
G.A. Carson ,
S. Smith ,
L. Peng  and
M.H. Nassir
M.A. Langell
Affiliation:
Department of Chemistry, University of Nebraska-Lincoln
G.A. Carson
Affiliation:
Department of Chemistry, University of Nebraska-Lincoln
S. Smith
Affiliation:
Department of Chemistry, University of Nebraska-Lincoln
L. Peng
Affiliation:
Department of Chemistry, University of Nebraska-Lincoln
M.H. Nassir
Affiliation:
Department of Chemistry, University of Nebraska-Lincoln
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Abstract

Despite the relevance to a variety of materials applications, the electronic and bonding properties of spinel transition metal oxides are not well established. We report here the slow oxidation of CoO(100) to Co3O4, studied by photoemission (UPS and XPS), low energy electron diffraction (LEED) and high resolution electron energy loss spectroscopy (HREELS) with the aim of elucidating the valence band electronic structure of the Co3O4 spinel. The original Mott insulator picture of the parent CoO substrate has been revised in recent times, after careful analyses and extensive debate, to the more detailed charge-transfer insulator model which includes some admixture of oxygen 2p levels in the 3d-derived valence band. No equivalent band structure analysis has been performed on the spinel oxides, perhaps in part because of the greater complexity of the 56-atom unit cell with two different cation lattice sites and oxidation states. In this study, we determine the valence band structure of the spinel oxide and address the question of whether Co3O4 can be modeled as a charge-transfer insulator in analogy with its closely related rocksalt substrate.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 547: Symposium DD – Solid-State Chemistry of Inorganic Materials II , 1998 , 255
Copyright
Copyright © Materials Research Society 1999

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