Defect centers and thermoluminescence in Al2O3:Si,Ti

Al2O3:Si,Ti is a sensitive thermoluminescent phosphor. ESR studies have been carried out in order to study the characteristics of the defect centers and the TL peaks observed in this phosphor. Two types of ESR centers (center I and center II) have been identified in Al2O3:Si,Ti. Center I is characteristic of a species exhibiting an isotropic g-value 2.0096 with a line width of 50 G. Center II is also characterized by an isotropic g-value 1.9526 with a line width of about 40 G. Thermal decay of center I shows three different annealing stages in the temperature ranges 125-225 deg. C, 430-525 deg. C and 600-680 deg. C, which indicates correlation between center I and TL peaks at 175, 475 and 625 deg. C, respectively. Decay of center II in the region 600-700 de. C appears to relate with the TL peak around 625 deg. C