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Portrait of Reine Wallenberg. Photo: Kennet Ruona

Reine Wallenberg

Professor, Coordinator Materials Science

Portrait of Reine Wallenberg. Photo: Kennet Ruona

Defect and electrical transport properties of Nb-doped SrTiO3

Author

  • Peter Blennow Tullmar
  • Anke Hagen
  • Kent K. Hansen
  • Reine Wallenberg
  • Mogens Mogensen

Summary, in English

This study reports the defect and electrical transport properties of Nb-doped SrTiO3, Samples with various A/B-ratios were synthesized by a modified glycine-nitrate combustion process and evaluated as a constituent in a SOFC anode. The phase purity and defect structure of the materials have been analyzed with SEM, XRD, TGA, and XANES. The electrical conductivity of Nb-doped strontium titanate (Sr0.94Ti0.9Nb0.1O3 - sintered in 9% H-2/N-2 at 1400 degrees C for 12 h) decreased with increasing temperature and showed a phonon scattering conduction mechanism with (sigma>120 S/cm at 1000 degrees C (in 9% H-2/N-2). The results were in agreement with the defect chemistry model of donor-doped SrTiO3 where the charge compensation changes from Sr vacancy compensation to the electronic type when samples are sintered in reducing atmosphere. XANES in combination with TGA indicated that Ti is the only species that is reduced to a lower oxidation state (from Ti4+ to Ti3+). The pre-edge fine structure (PEFS) from the XANES results indicated that Nb improved the overlap of the Ti atomic orbitals and thereby provided one more explanation for the positive effect of Nb on the electronic conductivity of Nb-doped SrTiO3. (C) 2008 Elsevier B.V. All rights reserved.

Department/s

  • Centre for Analysis and Synthesis

Publishing year

2008

Language

English

Pages

2047-2058

Publication/Series

Solid State Ionics

Volume

179

Issue

35-36

Document type

Journal article

Publisher

Elsevier

Topic

  • Chemical Sciences

Keywords

  • Conductivity
  • Nb-doped SrTiO3
  • Defect chemistry
  • XANES
  • XRD

Status

Published

ISBN/ISSN/Other

  • ISSN: 0167-2738