Thermally stimulated luminescence and EPR studies on topaz

In the present work, electron paramagnetic resonance (EPR) spectra and thermoluminescence (TL) emission of colourless natural topaz from Santo Antônio do Jacinto, Brazil, was studied as a function of thermal treatment and gamma irradiation dose, focussing on the use of this material as a radiation dosimeter. EPR measurements on “as-received” samples at room temperature provided signals in the region of about 500 at 5000 G. The signal located around g≅2g≅2, frequently attributed to (AlO4)0, increased with additional gamma dose and disappeared after thermal treatment at 500 °C for 1 h. Irradiation after thermal treatment recovered this signal. The decay promoted by isochronal thermal treatment showed the (AlO4)0 defects to be directly related to the TL glows peaks. The variation of EPR spectrum with annealing temperature prior to irradiation showed that the variation of TL sensitivity is a consequence of the variation of the (AlO4)0 population.