PREPARATION OF LITHIUM FLUORIDE-BASED THERMOLUMINESCENT MATERIALS

摘要

1496674 Thermoluminescence BRITISH NUCLEAR FUELS Ltd 12 Sept 1975 [13 Sept 1974] 40065/74 Heading C4S A method for preparing thermoluminescent LiF activated by Mg and Ti includes the steps of maintaining a mixture of LiF with Mg and Ti salts above the m.p. of LiF in an inert atmosphere for sufficient time to allow metallic ions of the salts to diffuse into the lattice, cooling the molten mixture in argon to a temperature allowing limited aggregation of the Mg ions, holding at that temperature to ensure such aggregation is uniform throughout the mixture, cooling rapidly in argon to restrict further aggregation, and breaking up the product into finely divided crystals. Subsequent annealing may be at 500‹ C. followed by rapid quenching in cold water. The salts may be magnesium chloride and titanium chloride respectively providing Mg and Ti in amounts 200 and 10 p.p.m. Temperatures and times are given. The fluoride may contain Li isotopes in natural proportions or may contain predominantly Li-6 or Li-7 for thermal neutron detection. LiF has a near tissue equivalence and may be used for dosimetry. Also mentioned are known LiF with MgCa, Eu, Al, Ti and (Mg + Eu) activators.