Niobium segregation in niobium-doped titanium dioxide (rutile).

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dc.contributor.authorAtanacio, AJen_AU
dc.contributor.authorBak, Ten_AU
dc.contributor.authorNowotny, Jen_AU
dc.date.accessioned2014-11-19T02:53:52Zen_AU
dc.date.available2014-11-19T02:53:52Zen_AU
dc.date.issued2014-05-29en_AU
dc.date.statistics2014-11-19en_AU
dc.description.abstractThis work determined the effect of niobium segregation on the surface and near-surface composition of Nb-doped TiO2, containing 0.18 atom % Nb and 0.018 atom % Nb, after annealing in the gas phase of controlled oxygen activity. The segregation-induced concentration profiles were determined using a range of analytical techniques of different depth resolution, including secondary ion mass spectrometry (SIMS), X-ray photoelectron spectroscopy (XPS), Rutherford backscattering (RBS), and proton-induced x-ray emission (PIXE). The XPS analysis of the 0.18 atom % Nb specimen annealed at 1273 K in oxidizing conditions and showed segregation-induced niobium surface enrichment of 2.83 atom % and 2.35 atom % in p(O-2) = 75 kPa and p(O-2) = 10 Pa, respectively. However, annealing at 1273 K in strong reducing conditions, p(O-2) = 10(-10) Pa, leads to depletion of the surface layer in niobium to the level of 0.05 atom % (desegregation). The results of SIMS, RBS, and XPS are consistent. The derived theoretical model, explaining the effect of oxygen activity on niobium segregation, considers contribution from three driving forces of segregation, including (i) strain relaxation, (ii) the formation of a low-dimensional surface structure, and the (iii) electric field associated with the surface charge. The established effect of oxygen activity on niobium segregation/desegregation may be used as a technology for imposition of (i) controlled surface composition that is required to achieve enhanced performance of TiO2 in solar-to-chemical energy conversion and (ii) chemically induced electric field required for charge separation. © 2014, American Chemical Society.en_AU
dc.identifier.citationAtanacio, A. J., Bak, T., & Nowotny, J. (2014). Niobium segregation in niobium-doped titanium dioxide (rutile). Journal of Physical Chemistry C, 118(21), 11174-11185. doi:10.1021/jp4110536en_AU
dc.identifier.govdoc5778en_AU
dc.identifier.issn1932-7447en_AU
dc.identifier.issue21en_AU
dc.identifier.journaltitleJournal of Physical Chemistry Cen_AU
dc.identifier.pagination11174-11185en_AU
dc.identifier.urihttp://dx.doi.org/10.1021/jp4110536en_AU
dc.identifier.urihttp://apo.ansto.gov.au/dspace/handle/10238/6057en_AU
dc.identifier.volume118en_AU
dc.language.isoenen_AU
dc.publisherAmerican Chemical Societyen_AU
dc.subjectNiobiumen_AU
dc.subjectDiffusionen_AU
dc.subjectTitaniumen_AU
dc.subjectKineticsen_AU
dc.subjectSegregationen_AU
dc.subjectOxygenen_AU
dc.titleNiobium segregation in niobium-doped titanium dioxide (rutile).en_AU
dc.typeJournal Articleen_AU
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