Defect chemistry of Ti and Fe impurities and aggregates in Al 2O3

Jessica K. Bristow, Davide Tiana, Stephen C. Parker, Aron Walsh

Research output: Contribution to journalArticle

13 Citations (Scopus)

Abstract

We report a theoretical evaluation of the properties of iron and titanium impurities in sapphire (corundum structured α-Al2O 3). Calculations using analytical force fields have been performed on the defect structure with the metals present in isolated, co-doped and tri-cluster configurations. Crystal field parameters have been calculated with good agreement to available experimental data. When titanium and iron are present in neighbouring face and edge-sharing orientations, the overlap of the d-orbitals facilitates an intervalence charge transfer (FeIII/Ti III → FeII/TiIV) with an associated optical excitation energy of 1.85 eV and 1.76 eV in the respective configurations. Electronic structure calculations based on density functional theory confirm that FeIII/TiIII is the ground-state configuration for the nearest-neighbour pairs, in contrast to the often considered FeII/TiIV pair. Homonuclear intervalence charge transfer energies between both FeIII/FeII and Ti IV/TiIII species have also been calculated, with the energy lying in the infra-red region. Investigation of multiple tri-clusters of iron and titanium identified one stable configuration, TiIII-(Ti IV/FeII), with the energy of electron transfer remaining unchanged. This journal is

Original languageEnglish
Pages (from-to)6198-6208
Number of pages11
JournalJournal of Materials Chemistry A
Volume2
Issue number17
DOIs
Publication statusPublished - 2014 May 7

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Renewable Energy, Sustainability and the Environment
  • Materials Science(all)

Fingerprint Dive into the research topics of 'Defect chemistry of Ti and Fe impurities and aggregates in Al <sub>2</sub>O<sub>3</sub>'. Together they form a unique fingerprint.

  • Cite this