Influence of carbon templates and Yb 3+ concentration on red and green luminescence of uniform Y 2O 3:Yb/Er hollow microspheres
Abstract
Uniform Yb 3+ and Er 3+-codoped Y 2O 3 hollow microspheres were synthesized via urea co-precipitation using carbon spheres as templates. Intense red emission ( 4F 9/2→ 4I 15/2) and weak green emission ( 2H 11/2, 4S 3/2→ 4I 15/2) of Er 3+ were observed for the Yb 3+ and Er 3+-codoped Y 2O 3 hollow microspheres under 980 nm infrared excitation. The integrated intensity of visible emission and the ratio of red to green were found to be strongly dependent on the amount of carbon sphere templates and the concentration of Yb 3+ ions. The amount of carbon sphere templates also plays an important role in adjusting the size of crystallite. Multi-phonon relaxation resulted from the absorbents (OH ‑ and CO 3 2‑) on the surface of the crystallite, and efficient occur of energy transfer processes and cross-relaxation between Er 3+ and Yb 3+ are responsible for the enhancement of intensity ratio of red to green emission. Interestingly, for higher concentration of Yb 3+ ions, the green emission is assigned to a three-phonon process in Y 2O 3:Yb/Er hollow microspheres, which also could result in the increase of the red to green emission ratio. An explanation to account for these behaviors was presented.
- Publication:
-
Journal of Luminescence
- Pub Date:
- January 2011
- DOI:
- 10.1016/j.jlumin.2011.02.031
- Bibcode:
- 2011JLum..131.1198T
- Keywords:
-
- Y <SUB loc="post">2</SUB>O <SUB loc="post">3</SUB>:Yb/Er;
- Hollow microspheres;
- Luminescence;
- Ratio