Local structure of low-temperature gamma -Al sub(2)O sub(3) phases as determined by the luminescence of Cr super(3+) and Fe super(3+)

The gamma and gamma * phases of alumina synthesized from crystalline boehmite and pseudoboehmite were shown to strongly differ in some physicochemical characteristics. Photoluminescence of Cr super(3+) and Fe super(3+) as luminescent probes with their natural impurity concentrations was detected in...

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Bibliographic Details
Published in:RSC advances 2014-12, Vol.5 (8), p.5686-5694
Main Authors: Rastorguev, Alexander, Baronskiy, Mark, Zhuzhgov, Aleksey, Kostyukov, Anton, Krivoruchko, Oleg, Snytnikov, Valeriy
Format: Article
Language:English
Subjects:
Aluminum oxide
Boehmite
Crystal defects
Crystal structure
Luminescence
Molecular structure
Phases
Synthesis
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Summary:The gamma and gamma * phases of alumina synthesized from crystalline boehmite and pseudoboehmite were shown to strongly differ in some physicochemical characteristics. Photoluminescence of Cr super(3+) and Fe super(3+) as luminescent probes with their natural impurity concentrations was detected in the tested alumina samples and the local structure of the samples was examined. The crystal field strength and Racah parameters in gamma -Al sub(2)O sub(3) phases were determined. The ratio of octahedral and tetrahedral cationic positions was equal to 1 for gamma -Al sub(2)O sub(3) synthesized from crystalline boehmite, and 0.3 for that obtained from pseudoboehmite. The effect of residual OH groups and weakly bound molecular water on the local structure of gamma -Al sub(2)O sub(3) phases was revealed. The luminescence of Cr super(3+) was detected in subsurface structures of each alumina; defects produced by nanocrystallites were shown to affect the luminescence.
ISSN:2046-2069
DOI:10.1039/c4ra14524k