Publication: Understanding the effects of Cr doping in rutile TiO₂ by DFT calculations and X-ray spectroscopy
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Publication Date
2018-05-07
Authors
Vásquez, G. C.
Magnano, Elena
Nappini, Silvia
Karazhanov, Smagul Zh.
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Nature Publishing Group
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Abstract
The effects of Cr on local environment and electronic structure of rutile TiO₂ are studied combining theoretical and experimental approaches. Neutral and negatively charged substitutional Cr impurities Cr_(Ti)(0)* and Cr_(Ti)(-1)* as well as Cr-oxygen vacancy complex 2Cr_(Ti) + V₀ are studied by the density functional theory (DFT) within the generalized gradient approximation (GGA) of Perdew-Burke-Ernzerhof (PBE) functional. Experimental results based on X-Ray absorption spectroscopy (XAS) and X-Ray photoelectron spectroscopy (XPS) performed on Cr doped TiO₂ at the Synchrotron facility were compared to the theoretical results. It is shown that the electrons of the oxygen vacancy tend to be localized at the t_(2g) states of the Cr ions in order to reach the stable oxidation state of Cr(3+)*. Effects of Cr on crystal field (CF) and structural distortions in the rutile TiO₂ cell were analyzed by the DFT calculations and XAS spectra revealing that the CF and tetragonal distortions in TiO₂ are very sensitive to the concentration of Cr.
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© Te Author(s) 2018.
Tis work was supported by MINECO/FEDER (Projects No. MAT 2015-65274-R and MAT2016- 81720-REDC), NILS Project (008-ABELCM-2013), Notur Project No. nn4608k, and HyMatSiRen No. project272806 from the Research Council of Norway.