Thermoluminescent and stuctural properties of BaAl2O4:Eu,Nd,Gdphosphors prepared by combustion method |
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Authors: | BM Mothudi MA Lephoto OM Ntwaeaborwa JR Botha HC Swart |
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Institution: | 1. Department of Physics, University of the Free State, P/B bag X 13, Phuthaditjaba, 9866/P.O. Box 339, Bloemfontein, ZA 9300, South Africa;2. Department of Physics, Nelson Mandela Metropolitan University, Port Elizabeth, ZA 6031, South Africa |
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Abstract: | BaAl2O4:Eu2+,Nd3+,Gd3+ phosphors were prepared by a combustion method at different initiating temperatures (400–1200 °C), using urea as a comburent. The powders were annealed at different temperatures in the range of 400–1100 °C for 3 h. X-ray diffraction data show that the crystallinity of the BaAl2O4 structure greatly improved with increasing annealing temperature. Blue-green photoluminescence, with persistent/long afterglow, was observed at 498 nm. This emission was attributed to the 4f65d1–4f7 transitions of Eu2+ ions. The phosphorescence decay curves were obtained by irradiating the samples with a 365 nm UV light. The glow curves of the as-prepared and the annealed samples were investigated in this study. The thermoluminescent (TL) glow peaks of the samples prepared at 600 °C and 1200 °C were both stable at ∼72 °C suggesting that the traps responsible for the bands were fixed at this position irrespective of annealing temperature. These bands are at a similar position, which suggests that the traps responsible for these bands are similar. The rate of decay of the sample annealed at 600 °C was faster than that of the sample prepared at 1200 °C. |
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Keywords: | BaAl2O4:Eu2+ Nd3+ Gd3+ Phosphorescence Thermoluminescence Trap depth Trapped-carriers |
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