An XPS Study of the Effect of Ion Bombardment on Transition Metal Oxides


The effect of ion bombardment on various transition metal oxides has been investigated by means of XPS. These oxides are commercially obtained powders of FeO, Fe304, Fe2O3, CoO, Co304, TiO2, ZrO, Nb2O5, Ta2O5 and WO3. In order to establish the beam induced effects, it is necessary to characterize the unbombarded oxide surface. For each oxide this has been carried out by determination of the binding energies associated with the core-electron levels of the metal and oxygen in various chemical states. In addition, the bulk-purity of the oxides were investigated using X-ray powder diffraction technique. Ion bombardment induced surface compositional changes of all oxides have been observed through a chemical reduction to the lower oxidation states and eventually to the metallic state. The results found have been quantified to yield the extent of the surface compositional change. This quantification is given in terms of the (metal to oxygen)-surface to bulk ratio, which enables comparisons to be made with predictions of the linear cascade theory of preferential sputtering. Theoretical understanding of the ion bombardment induced compositional changes in oxides is currently insufficient, mainly due to a lack of quantified experimental evidence. The results found here thus provide an extensive basis of quantitative information. In addition to the effect of ion bombardment on the surface chemistry of the oxides, investigations involving the influence of the primary beam energy, current density , dose, mass and charge of the projectile on the extent of the chemical damage are also carried out. The results have been compared with recent theories of preferential removal of oxygen.

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Divisions: Aston University (General)
Additional Information: Copyright © Choudhury, 1991. T. Choudhury asserts their moral right to be identified as the author of this thesis. This copy of the thesis has been supplied on condition that anyone who consults it is understood to recognise that its copyright rests with its author and that no quotation from the thesis and no information derived from it may be published without appropriate permission or acknowledgement. If you have discovered material in Aston Publications Explorer which is unlawful e.g. breaches copyright, (either yours or that of a third party) or any other law, including but not limited to those relating to patent, trademark, confidentiality, data protection, obscenity, defamation, libel, then please read our Takedown Policy and contact the service immediately.
Institution: Aston University
Uncontrolled Keywords: ion bombardment,preferential sputtering,transition meetal oxides,x-ray photoelectron spectroscopy,surface compositional change.
Last Modified: 11 Dec 2023 13:59
Date Deposited: 11 Feb 2015 10:30
Completed Date: 1991
Authors: Choudhury, Tanima

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