Thermally stimulated polarisation and depolarisation currents (TSPC and TSDC) in LiF:Mg²⁺(TLD-100)

From a consideration of the temperature dependence of the Langevin function, thermally stimulated polarisation currents (TSPC) ought to exhibit a current reversal at temperature greater than the temperature of the TSPC maximum. The authors report measurements of TSPC and TSDC (depolarisation currents) in LiF:Mg 2+ (TLD-100) in which the current reversal is clearly observed for the first time in alkali halides. The TSPC and TSDC signals arise from the orientation of Mg 2+ -Li + vacancy dipoles, with an activation energy of 0.66 eV and a pre-exponential factor of 10 14 s -1 . By comparing the areas under the TSPC and TSDC curves, the value of the effective polarisation temperature in the TSDC measurement can be estimated.