Electron paramagnetic resonance study of rare-earth related centres in K2YF5:Tb thermoluminescence phosphors |
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Authors: | DG Zverev |
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Affiliation: | a Department of Solid State Sciences, Ghent University, Krijgslaan 281-S1, B-9000 Ghent, Belgium b Experimental Condensed Matter Physics, Department of Physics, University of Antwerp, Universiteitsplein 1, B-2610 Antwerpen, Belgium |
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Abstract: | Rare-earth related centres have been investigated in K2YF5:Tb3+ crystals, exhibiting thermoluminescence (TL) below and above room temperature (RT), using electron paramagnetic resonance (EPR) spectroscopy at Q (34 GHz) and W-band (94 GHz). The spectra have been studied prior to irradiation, after exposure in the kGy range to X-rays at 77 K and subsequent pulse annealing up to 570 K. In addition to Gd3+, previously studied in detail, we identified Er3+ and Yb3+ centres as accidental impurities in as-grown crystals and determined their effective g tensors. The EPR spectra of irradiated and annealed crystals provide evidence for the production of at least three distinct Tb-related trapped hole centres, two of which could definitely be identified as Tb4+. Hence, we prove that the Tb3+ activator ions also act as hole traps in K2YF5. Pulse annealing experiments indicate that the TL above RT results from thermal release of electrons, recombining at these Tb4+ ions. |
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Keywords: | Electron paramagnetic resonance EPR K2YF5 Thermoluminescence (TL) Tb |
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