TEMPERATURE-DEPENDENCE OF THE X-RAY-INDUCED LUMINESCENCE OF AL-NA-CONTAINING QUARTZ CRYSTALS

The X-ray induced luminescence (XL) of quartz containing aluminum with sodium as the charge compensating monovalent ion, Q(Na), was found to decrease on warming in four steps: at 100-150, 150-200, 250-350 and at 450-550 K, labeled as Stages I-IV, respectively. Stages I and II were independent of thermal or irradiation pretreatments, emitted at energies under 3 eV, and appeared at the same temperatures for both Q(Na) and Q(Li). This suggests that the defects involved in the decrease of the XL in these stages do not involve the monovalent ions. Stage III of Q(Li) was ''formed'' by pre-irradiation at temperatures in the range 150-300 K compared to the range 180-350 K for the Stage III formation curve of Q(Na). These formation curves were found to fit those of thermoluminescence (TL) peaks at 202 K and 190 K in Q(Na) and Q(Li), respectively. This implies the involvement of the [SiO4/M+]0 (M+ = Na+ or Li+) centers in the respective Stage III XL emissions. Stage IV also depended on the pretreatment of the samples in both Q(Na) and Q(Li), and just as in Stage III, the emission at Stage IV was at 3.2 eV (about 380 nm). Still, in Q(Li) samples Stage IV was bleachable by annealing at 600 K, while in Q(Na) even warming to 850 K did not bleach the Stage IV XL. On the other hand, Stage IV XL of Q(Na) was bleached partially by prolonged X-irradiation at suitable temperatures which was not observed in Q(Li) samples. It is suggested that Stage IV involves the trapping of the M+ ions at [X(i)/M+]+ centers, where X(i) are unidentified defects in quartz which are more stable and resistant to thermal bleaching in Q(Na) than in Q(Li). Analysis of the results suggests that the recombination center for the 3.2 eV emission is the [AlO4]0 center.