Characterization of synthetic virgilite-petalite mixed crystals by thermoluminescence and X-ray diffraction

This paper reports on the dose response and fading effect of the blue thermoluminescence (TL) emission of lithium-rich aluminosilicates (virgilite-petalite mixture) synthesized by sol-gel method and characterised by means of X-ray diffraction. This material could be potentially valid for dose assessment since: (i) it is sensitive to ionising radiation, (ii) the dose dependence in the range of 0.5-5 Gy exhibits an acceptable linearity and (iii) the stability of the TL signal, after four months of storage, shows an initial rapid decay (ca. 55%) maintaining similar relative intensities from 40 to 50 days onwards. The structure of the TL emission has been analysed by means of a computerized glow curve fitting method based on general order kinetics. The calculation of the trapping parameters of each of the four glow peaks appearing at 80, 95, 110 and 125 °C (i.e. trap depth in eV, E; frequency factor in s-1, s, and the order of kinetics, b) indicates that cannot be fitted to a typical first or second order kinetics; the estimated b values are between 1.1 and 1.8