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Title: Optical Absorption and Spectral Photoconductivity in α-(Fe 1-xCr x) 2O 3 Solid-Solution Thin Films

Hematite, α-Fe 2O 3, is an attractive narrow gap oxide for consideration as an efficient visible light photocatalyst, with significant potential for band gap engineering via doping. We examine optical absorption in α (Fe 1-xCrx) 2O 3 epitaxial films and explain the observed excitations, and the nature of the band gap dependence on x, through first principles calculations. The calculated and measured optical band gap becomes smaller than that of the bulk α-Fe 2O 3 and reaches a minimum as the Cr mole fraction increases to 50%. The lowest energy transitions in the mixed-metal alloys involve electron excitation from occupied Cr 3d orbitals to unoccupied Fe 3d orbitals, and they result in a measureable photocurrent. The onset of α-Fe 2O 3 photoconductivity can be reduced by nearly ~0.5 eV through addition of Cr.
 [1] ;  [1] ;  [1] ;  [1] ;  [2] ;  [2] ;  [1] ;  [3] ;  [1]
  1. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
  2. Univ. of Washington, Seattle, WA (United States)
  3. Univ. College London (United Kingdom)
Publication Date:
OSTI Identifier:
Report Number(s):
Journal ID: ISSN 0953-8984; 47703; KC0304030; KC0301020
DOE Contract Number:
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Physics. Condensed Matter; Journal Volume: 25; Journal Issue: 39
IOP Publishing
Research Org:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL)
Sponsoring Org:
Country of Publication:
United States
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; Optical Absorption; Spectral Photoconductivity; DFT; TDDFT; Embedded Cluster; Iron Oxide; Chromium Oxide; Environmental Molecular Sciences Laboratory