Kinetic analysis of high temperature secondary thermoluminescence glow peaks in α-Al2O3:C

Abstract

The kinetic analysis of secondary glow peaks in carbon-doped aluminium oxide is reported. A glow curve measured at 0.4 °C s−1 after beta irradiation to 3 Gy revealed at least five peaks as a result of various techniques of glow curve resolution; the dominant peak at 156 °C (peak II) and two weaker-intensity secondary peaks one at 36 °C (peak I) and the other at 264 °C (peak III). Peaks IIA and IV at 170 and 422 °C respectively only became apparent after removal of preceding more prominent peaks. The secondary peaks are particularly weak in intensity and are as usual dominated by the main dosimetry peak. The analysis in this report focusses on peak III, usually seen adjacent to the main dosimetry peak but whose presence is masked by the extreme sensitivity of the latter. Complementary analyses of the weaker intensity peaks I, IIA and IV are included. Peaks I, IIA and III are subject to first-order kinetics while for peaks II and IV the issue is less conclusive. The activation energy increases from 0.72 eV for peak I to about 1.3 eV for peak IV with values for peak II and IIA similar at ∼1 eV. In general, the frequency factor corresponding to the lower temperature peaks (I, II, and IIA) have values (1010–1012 s−1) that are an order of magnitude or so greater than for peaks III and IV (109–1011 s−1). Except for peak I, peak II and all other secondary peaks are affected by thermal quenching whose activation energy was determined as ΔE = 0.95 ± 0.04 eV using peak IIA and as ΔE = 1.48 ± 0.10 eV using peak III. The overall conclusion is that all peaks correspond to electron traps and are associated with the same recombination centre.