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The g and g* phases of alumina synthesized from crystalline boehmite and pseudoboehmite were shown to strongly differ in some physicochemical characteristics. Photoluminescence of Cr 3+ and Fe 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 g-Al 2 O 3 phases were determined. The ratio of octahedral and tetrahedral cationic positions was equal to 1 for g-Al 2 O 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 g-Al 2 O 3 phases was revealed. The luminescence of Cr 3+ was detected in subsurface structures of each alumina; defects produced by nanocrystallites were shown to affect the luminescence.

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Photoluminescence of Cr3+ in nanostructured α-Al2O3 synthesized by evaporation using a continuous wave CO2 laser.

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