Thermoluminescence of a lithium aluminium rich beta quartz for dosimetry purposes

Abstract

A member of the ß-quartz series (Li0.73Al0.73Si1.27O4) was synthesised using the ceramic method from precursor powders - Li2CO3, Al(NO3)3.9H2O, Si(C2H5O)4 - with identical composition. Crystallisation of the gel was obtained by heating the raw material at 800°C for 12 h. The XRD pattern of the synthetic sample indicates a ß-quartz structure with hexagonal symmetry. Thermoluminescence (TL) signals of annealed samples at 1200°C for 12 h, and non-annealed samples, were measured in the UV blue region of the spectrum. The non-annealed irradiated ß-quartz displays two TL peaks at 110°C and 280°C which, after different additional radiation doses (from 0.4 to 5 Gy), display high linearity. The other annealed irradiated aliquots show a similar behaviour and stronger linearity. Thermal treatments at high temperature (1200°C) produce ionic self-diffusion and loss of lithium atoms through the open hexagonal channel of the ß-quartz structure. These [AlO4/Li+](o) defects are responsible for the high radiation sensitivity of the sample.This work has been funded by the DGICYT project PB 95-0108-B and a CSN contract 96/208Peer Reviewe