Thermoluminescence in Sintered CaB4O7:Dy and CaB4O7:Eu

Abstract

Abstract TL in sintered CaB4O7 doped with activators, such as Eu, Dy and also Pb and Cu, has been investigated. For a heating rate of 20 oC.min-1, the TL glow peaks can be roughly grouped into three temperature regions: (I) 75~110 oC, (II) 170~190 oC, and (III) 255~275 oC. Their emission spectra depend on the activator and its valence. The activators release to the luminescence in the following way: Eu2+ to 440 nm, Dy3+ to 480 and 580 nm, Pb2+ to 275 nm, and Cu+ to 540 nm, respectively. Thermally stimulated current (TSC) was observed corresponding to all the temperatures at which TL glow peaks were observed. This indicates that the thermally released charge carriers recombine with the luminescent centres through conduction or/and valence bands, and not by a tunnelling process. All the TL glow peaks showed no supralinearity before they saturated at an exposure of about 2.58 C.kg-1 (104 R). Peaks appearing at the temperature regions II and III retained memories of irradiation for a storage period of 6 months in the dark at room temperature.