Order and disorder around Cr super(3+) in chromium doped persistent luminescent AB sub(2)O sub(4) spinels

The X-ray absorption near edge structure (XANES) spectroscopy technique is used to better understand the charging and decharging processes of the persistent luminescence in the Cr super(3+)doped AB sub(2)O sub(4) spinels (A = Zn, Mg and B = Ga and Al) with low photon energy excitation by visible lig...

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Bibliographic Details
Published in:Physical chemistry chemical physics : PCCP 2015-04, Vol.17 (16), p.10993-10999
Main Authors: Basavaraju, Neelima, Priolkar, Kaustubh R, Gourier, Didier, Bessiere, Aurelie, Viana, Bruno
Format: Article
Language:English
Subjects:
Aluminum
Cationic
Chromium
Clustering
Clusters
Inversions
Luminescence
Spinel
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Summary:The X-ray absorption near edge structure (XANES) spectroscopy technique is used to better understand the charging and decharging processes of the persistent luminescence in the Cr super(3+)doped AB sub(2)O sub(4) spinels (A = Zn, Mg and B = Ga and Al) with low photon energy excitation by visible light. Cr K edge XANES spectra have been simulated for different near neighbour environments around the Cr super(3+) recombination centres and compared with the experimental curve. In the Cr super(3+):ZnGa sub(2)O sub(4) compound, the Cr super(3+) local structure corresponds mostly to that of a normal spinel ( similar to 70%), while the rest comprises of a distorted octahedral environment arising from cationic site inversion and a contribution from chromium clustering. This local structure is considerably different in Cr super(3+):MgGa sub(2)O sub(4) and Cr super(3+):ZnAl sub(2)O sub(4), where, for both cases, chromium clustering represents the main contribution. The strong correlation between the intensity of persistent luminescence and the percentage of Cr in clusters leads us to infer that the presence of Cr clusters is responsible for the decrease of the intensity of the visible light induced persistent luminescence in the Cr super(3+) doped AB sub(2)O sub(4) spinels.
ISSN:1463-9076
1463-9084
DOI:10.1039/c5cp01097g