Efficient energy transfer and photoluminescent characteristics in SrAl_(12)O_(19):Eu~(2+), Cr~(3+) nano-rods

摘要

Cr~(3+) singly doped and Eu~(2+), Cr~(3+) co-doped SrAl_(12)O_(19) nano-rods with different diameters have been prepared by a combustion method. A new emission band of Cr~(3+) centered at 704 nm on the low energy side of the R-line at 688 nm originating from the ~2E-~4A_2 transition of Cr~(3+) is observed. This band enhances with decreasing diameter of the nano-rods, implying its origin in the Cr~(3+) ions on the surface of the nano-rods. Photoluminescence study and fluorescence lifetime measurements demonstrate efficient energy transfer from Eu~(2+) to Cr~(3+) in SrAl_(12)O_(19) nano-rods in comparison with the corresponding bulk materials. This result is attributed to a large spectral overlap between the Eu~(2+) emission band and the ~4A_2-~4T_1 (F) absorption band of Cr~(3+) on the surface of the nano-rods.