Recombination processes in rare-earth doped MAl2O4(M = Ca, Sr) persistent phosphors investigated by optically-detected magnetic resonance
✍ Scribed by Schweizer, S. ;Henke, B. ;Rogulis, U. ;Yen, W. M.
- Book ID
- 105364141
- Publisher
- John Wiley and Sons
- Year
- 2007
- Tongue
- English
- Weight
- 232 KB
- Volume
- 204
- Category
- Article
- ISSN
- 0031-8965
No coin nor oath required. For personal study only.
✦ Synopsis
Abstract
Single crystalline MAl~2~O~4~ (M = Ca and Sr) persistent phosphors, which are nominally pure or additionally doped with Eu and Nd or Dy, respectively, were investigated for their recombination luminescence (RL) and microwave‐induced changes in the RL at low temperatures. The analysis of the optically‐detected electron paramagnetic resonance (EPR) spectra, recorded after ultraviolet excitation at 4.2 K, shows that intrinsic donor and acceptor centres are involved in the recombination process. Spectral dependent RL‐EPR measurements on undoped CaAl~2~O~4~ (CAO) and SrAl~2~O~4~ (SAO) show that we deal with only one donor but at least two different acceptors. The g value of the donor is 1.99 in CAO and 1.97 in SAO; the g value of the acceptors is about 2.02. The donor–acceptor recombination energy is either emitted directly (undoped samples) or almost completely transferred to the rare‐earth activators (doped samples). (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)