Correlation between electron paramagnetic resonance and thermoluminescence in natural sodalite |
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Authors: | N F Cano A R Blak S Watanabe |
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Institution: | 1. Institute of Physics, University of S?o Paulo, Rua do Mat?o, Travessa R, 187, S?o Paulo, CEP 05508-900, Brazil
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Abstract: | Samples of natural sodalite, Na8Al6Si6O24Cl2, submitted to gamma irradiation and to thermal treatments, have been investigated using the thermoluminescence (TL) and electron
paramagnetic resonance (EPR) techniques. Both, natural and heat-treated samples at 500°C in air for 30 min, present an EPR
signal around g = 2.01132 attributed to oxygen hole centers. The EPR spectra of irradiated samples show an intense line at g = 2.0008 superimposed by a hyperfine multiplet of 11 lines due to an O− ion in an intermediate position with respect to two adjacent Al nuclei. In the TL measurements, the samples were annealed
at 500°C for 30 min and then irradiated with γ doses varying from 0.001 to 20 kGy. All the samples have shown TL peaks at
110, 230, 270, 365, and 445°C. A correlation between the EPR g = 2.01132 line and the 365°C TL peak was observed. A TL model is proposed in which a Na+ ion acts as a charge compensator when an Al3+ ion replaces a Si4+ lattice ion. The γ ray destruction of the Al–Na complex provides an electron trapped at the Na and a hole trapped at a non-bridging
oxygen ion adjacent to the Al3+ ion. |
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