Effect of crystal structure and dopant concentration on the luminescence of Cr3+ in Al2O3 nanocrystals

✍ Scribed by A. Patra; R.E. Tallman; B.A. Weinstein

• Publisher: Elsevier Science
• Year: 2005
• Tongue: English
• Weight: 335 KB
• Volume: 27
• Category: Article
• ISSN: 0925-3467
• DOI: 10.1016/j.optmat.2004.10.002

✦ Synopsis

The sol-emulsion-gel method is used for the preparation of Cr 3+ -doped Al 2 O 3 nanocrystals. The luminescence spectra of Cr 3+ ions in Al 2 O 3 nanocrystals are found to be sensitive to the crystal structure and dopant concentration. It is found that a broad band emission in the range of 680-720 nm and the R-lines (R 2 , 692.9 and R 1 , 694.3 nm) are obtained at 900 °C (h-Al 2 O 3 ) and 1025 °C (a-Al 2 O 3 ) heat-treated 0.2 mol% Cr-doped Al 2 O 3 samples respectively. However, for higher concentrations of chromium (2 mol%) Rlines are obtained at 900 °C annealed samples and these lines are broadened and red shifted at 1025 °C annealed sample which is due to Cr-pair (and/or cluster) formation. The analysis suggests that luminescence properties of Cr 3+ ions are strongly dependent on concentration and crystal phase of the Al 2 O 3 nanocrystals.