Geometric and electronic structure of epitaxial NbxTi1-xO2 on TiO2(110)

S. A. Chambers, Y. Gao, Y. J. Kim, M. A. Henderson, S. Thevuthasan, S. Wen, K. L. Merkle

Research output: Contribution to journalArticle

30 Citations (Scopus)

Abstract

We have investigated the detailed geometric and electronic structure of MBE-grown NbxTi1-xO2 on TiO2(110) by means of high-resolution transmission electron microscopy, X-ray photoelectron diffraction, ultraviolet and X-ray photoemission and electron energy loss spectroscopy. We find no measurable change in the Nb-O bond length relative to that for Ti-O bonds in TiO2 in the dilute limit (x=0.05), and that the epitaxial layers remain strained and coherent with the substrate for x≤ ≈0.3. However, significant dislocation generation occurs for x> ≈0.3. Nb substitution for Ti in the lattice introduces an additional valence electron per atom. The resulting density of states falls in the valence band region, but no new state density occurs in the either the band gap or conduction band. This result is in contrast to what occurs in the very dilute limit (parts per thousand), where Nb electrons occupy a shallow donor level near the conduction band minimum. Based on the electron counting rule, the extra Nb electrons form a non-bonding band which is degenerate with the valence band. The significance of these results for enhanced thermal and photochemistry on NbxTi1-xO2 surfaces vis a vis TiO2 is discussed.

Original languageEnglish
Pages (from-to)625-637
Number of pages13
JournalSurface Science
Volume365
Issue number3
DOIs
Publication statusPublished - 1 Oct 1996
Externally publishedYes

Fingerprint

Electronic structure
electronic structure
Electrons
Valence bands
Conduction bands
valence
conduction bands
electrons
X rays
Photochemical reactions
Electron energy loss spectroscopy
Epitaxial layers
Bond length
Photoemission
High resolution transmission electron microscopy
Photoelectrons
Molecular beam epitaxy
Energy gap
Substitution reactions
Diffraction

Keywords

  • Electron-solid diffraction
  • Molecular beam epitaxy
  • Photoelectron spectroscopy
  • Single crystal epitaxy
  • Titanium oxide

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Condensed Matter Physics
  • Surfaces and Interfaces

Cite this

Chambers, S. A., Gao, Y., Kim, Y. J., Henderson, M. A., Thevuthasan, S., Wen, S., & Merkle, K. L. (1996). Geometric and electronic structure of epitaxial NbxTi1-xO2 on TiO2(110). Surface Science, 365(3), 625-637. https://doi.org/10.1016/0039-6028(96)00760-1

Geometric and electronic structure of epitaxial NbxTi1-xO2 on TiO2(110). / Chambers, S. A.; Gao, Y.; Kim, Y. J.; Henderson, M. A.; Thevuthasan, S.; Wen, S.; Merkle, K. L.

In: Surface Science, Vol. 365, No. 3, 01.10.1996, p. 625-637.

Research output: Contribution to journalArticle

Chambers, SA, Gao, Y, Kim, YJ, Henderson, MA, Thevuthasan, S, Wen, S & Merkle, KL 1996, 'Geometric and electronic structure of epitaxial NbxTi1-xO2 on TiO2(110)', Surface Science, vol. 365, no. 3, pp. 625-637. https://doi.org/10.1016/0039-6028(96)00760-1
Chambers SA, Gao Y, Kim YJ, Henderson MA, Thevuthasan S, Wen S et al. Geometric and electronic structure of epitaxial NbxTi1-xO2 on TiO2(110). Surface Science. 1996 Oct 1;365(3):625-637. https://doi.org/10.1016/0039-6028(96)00760-1
Chambers, S. A. ; Gao, Y. ; Kim, Y. J. ; Henderson, M. A. ; Thevuthasan, S. ; Wen, S. ; Merkle, K. L. / Geometric and electronic structure of epitaxial NbxTi1-xO2 on TiO2(110). In: Surface Science. 1996 ; Vol. 365, No. 3. pp. 625-637.
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AB - We have investigated the detailed geometric and electronic structure of MBE-grown NbxTi1-xO2 on TiO2(110) by means of high-resolution transmission electron microscopy, X-ray photoelectron diffraction, ultraviolet and X-ray photoemission and electron energy loss spectroscopy. We find no measurable change in the Nb-O bond length relative to that for Ti-O bonds in TiO2 in the dilute limit (x=0.05), and that the epitaxial layers remain strained and coherent with the substrate for x≤ ≈0.3. However, significant dislocation generation occurs for x> ≈0.3. Nb substitution for Ti in the lattice introduces an additional valence electron per atom. The resulting density of states falls in the valence band region, but no new state density occurs in the either the band gap or conduction band. This result is in contrast to what occurs in the very dilute limit (parts per thousand), where Nb electrons occupy a shallow donor level near the conduction band minimum. Based on the electron counting rule, the extra Nb electrons form a non-bonding band which is degenerate with the valence band. The significance of these results for enhanced thermal and photochemistry on NbxTi1-xO2 surfaces vis a vis TiO2 is discussed.

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