Effect of solution treatment temperature and ageing on TLD-100 crystals (ionic conduction measurement)

Abstract

A study of the influence of holding TLD-100 crystals at different solution temperatures, between 210 "C and 470 "C, on the thermoluminescent glow curve has revealed no effect. The ageing of TLD-100 crystals at 177 "C, 150 "C, 131 "C and 102 "C as followed by ionic conductivity measurements has shown that GLiF . MgFz precipitates in all cases. This strongly reduces the thermoluminescent response.(3 "C 11-1) leads to the precipitation of 6LiF. MgFz in the LiF matrix. For the particular composition of TLD-100 (estimated to be N 170 mole ppm Mg2+ ions) the solubility limit of the precipitated phase is 250 "C. Above this temperature the Mgz+ ions are all in solid solution; but, because of coulombic interactions, there is a tendency for thc Mg2+ ions and cation vacancies to form nearest neighbour pairs and higher-order clusters (see, for example, Dryden and Shuter 1973, Strutt and Lilley 197G). With increasing the crystal.