Thermoluminescence of monoclinic ZrO2: Kinetic analysis and dosimetric features

Abstract

Thermoluminescence (TL) of beta irradiated monoclinic-phase zirconium oxide (ZrO2) is reported. The sample produces intense emission, a feature that facilitated study of kinetic and dosimetric characteristics. Glow curves measured at 1 °C s−1 show two prominent peaks at 44 and 112°C. A secondary peak is observed at 240°C. For convenience the peaks are henceforth referred to as peak 1, peak 2 and peak 3. Peak 3 at 240°C is ill-defined and of particularly low intensity and was thus not studied any further. Repetitive measurements on the same aliquot confirm that ZrO2 exhibits excellent repeatability. The dose response of peak 1 at 44°C peak is linear for doses from 1 to 31 Gy. In comparison, the dose response of peak 2 at 112°C peak is linear between 10 and 21 Gy and then becomes supralinear thereafter up to 31 Gy. Peak 1 fades completely within 1800 s of irradiation whereas the intensity of peak 2 drops down to 59% of its initial value within 10800 s of irradiation. Regarding kinetic analysis, the Tm- Tstop procedure confirms that there are in fact five peaks in the glow curve of ZrO2. Peak 2 follows first order kinetics whereas peak 1 is subject to non-first order kinetics. The intensity of both peaks 1 and 2 decrease with heating rate. For peak 2, this shows that it is affected by thermal quenching. The corresponding value of activation energy for the thermal quenching was calculated as 1.20 ± 0.08 eV.