Synthesis, luminescent and dosimetric properties of Li2B4O7:Cu,Ag,Tm

Abstract

This work reports the preparation of a new thermoluminescent (TL) material obtained by doping the host salt of lithium borate with copper, silver and thulium ions (Li2B4O7:Cu, Ag, Tm). With the obtained material, sintered dosimeters in form of discs were made and exposed to gamma radiation from a 60Co source. It was found that these dosimeters show a sensitivity of approximately 40% of that shown by the commercial dosimeter TLD-100 (LiF:Mg,Ti). The thermally stimulated luminescence of the prepared material showed a linear response with dose for gamma radiation in the dose range from 0.001 to 50 Gy. Its luminescent signal remains constant during 24 h after irradiation, exhibiting a better behaviour than the commercial dosimeter TLD-800 (Li2B4O7:Mn) which decreases up to 60% of its original signal in the same period. The lower detection limit was determined to be equal to 0.1 mGy and TL measurements showed repeatability within 2.5%. The kinetic parameters were determined using several methods. The variable heating rate method showed the lowest energy value E of the main peak (peak 1). Initial rise and peak shape methods showed intermediate values whereas the deconvolution method showed the highest energy value E, using heating rates of 1, 2, 6 and 10 K/s. Results obtained from the morphology, crystallography, Raman spectroscopy and photoluminescence are also reported. These results suggest that this new thermoluminescent detector could be a promising material to use in clinical dosimetry applications.