Luminescence and energy transfer in TbAl3B4O12 |
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Authors: | F Kellendonk G Blasse |
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Institution: | Physical Laboratory, State University, P.O. Box 80.000, 3508 TA Utrecht, The Netherlands |
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Abstract: | An investigation of the luminescence properties of TbAl3B4O12 in the temperature region 1.4–300 K is reported. Laser site-selection and time-resolution techniques were used.The results show that energy migration among Tb3+ ions on the regular crystallographic sites occurs. The transfer characteristics at room temperature are consistent with a diffusion-limited transfer process to Mo3+ quenching centres. The diffusion constant and the critical transfer distance for Tb3+ → Mo3+ transfer are derived. The rate of diffusion increases for decreasing temperature. At about 60 K a transition from diffusion-limited transfer to trapping-limited transfer occurs. This behaviour is due to the variation in the diffusion constant with temperature. In the temperature region below 60 K transfer to Tb3+ traps is observed. The intensity of the emission from the traps increases exponentially with decreasing temperature. However, the overall transfer rate to Mo3+ and traps remains roughly constant. A simple model including time-independent transfer rates and back transfer from traps to intrinsic Tb3+ ions is proposed to explain the results. The rates of transfer to Mo3+ and traps are obtained. |
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