Thermoluminescence studies on Cu-doped Li2B4O7 single crystals

Abstract Lithium tetraborate (Li 2 B 4 O 7 ) is a tissue equivalent material and single crystals of this material doped with Cu are promising for dosimetric applications. In the present study highly transparent single crystals of lithium tetraborate (Li 2 B 4 O 7 ) doped with Cu (0.5 wt%) have been grown using the Czochralski technique. The Li 2 B 4 O 7 :Cu crystals were studied using photoluminescence, X-ray diffraction (XRD), UV–vis transmission, time resolved fluorescence and thermoluminescence (TL) techniques. The TL readout of Li 2 B 4 O 7 :Cu crystals showed two well-defined glow peaks at 402 K (peak-1) and 513 K (peak-2) for a 4 K/s heating rate. While the low temperature TL peak-1 fades completely within 24 h at room temperatures, the main dosimetric peak-2 remains the same. The TL sensitivity of the grown single crystal is found to be 3.3 times that of a conventional TL phosphor, TLD-100. The Li 2 B 4 O 7 :Cu crystals showed a linear TL dose–response in the range from 1 mGy to 1 kGy. The TL analysis using a variable dose method revealed first order kinetics for both the peaks. Trap depth and frequency factor for peak-1 were found to be 0.81 eV and 5.2×10 9  s −1 , whereas for peak-2 the values were 1.7 eV and 1.7×10 16  s −1 , respectively.