LAUSR

Abstract Thermoluminescence dosimeter (TLD) has been shown to be one of the most popular devices to measure absorbed radiation dose. Increasing applications of radiation in our day-to-day life motivates to develop efficient phosphor materials for TLD. LiF based TLD has attracted immense interest in the area of medical and industrial applications of radiation. Present study explored the origin of recent experimental observation of improvement of TL sensitivity of LiF due to doping with Mg, Cu and Ag. For this purpose, we have systematically investigated the geometry and electronic structure of LiF in absence and presence of individual dopant element as well as in combination using density functional theory as a tool. Present study indicates that the relative defect formation energy for doping with individual element and in combination is strongly dependent on the chemical environment. Our study reveals that the requirement of a good TLD material, i.e., electron trapping, hole trapping, and luminescent centers is not satisfied in presence of only individual dopant element. Interestingly, this condition is nicely fulfilled by simultaneous presence of all the three dopant elements. Each dopant element is found to play specific role in creating different types of trapping centers. Present study also explored the underlying mechanism of the TL process in (Mg, Cu, Ag)-doped LiF. To explain the origin of experimentally observed absorption and emission spectrum, we have calculated thermodynamic transition levels (TTLs), and optical transition levels for different doped systems. Finally, the present study predicts the emission range of (Mg, Cu, Ag)-doped LiF, which is known to be very much crucial for selecting the appropriate light detection system.