Determination of thermoluminescence properties of ZnB2O4:Tm3+,Li+ for dosimetric purposes


AKÇA S.

APPLIED RADIATION AND ISOTOPES, cilt.157, 2020 (SCI İndekslerine Giren Dergi) identifier identifier identifier

Özet

This study aims to investigate the comparison of the thermoluminescence (TL) emission of Li+ and Tm3+ codoped and un-doped zinc borate (ZnB2O4) phosphors prepared by wet chemical synthesis method. The crystal structure of the samples has been determined by means of X-ray powder diffraction and matched with the standard pattern of ZnB2O4 (PDF Card No. 039-1126). TL glow curves of 5 Gy beta irradiated Li+ (at different concentrations of 0.2, 0.5, 0.8 and 1.0%) and Tm3+ (1.0%) co-doped ZnB2O4 have been recorded using various band pass filters to determine both the optimum concentration and the suitable filter. The TL green emission (565 nm) of Li+ (1.0%), Tm3+ (1.0%) co-doped ZnB2O4 phosphor displays a complex structure where one can distinguish, at least, three groups of components peaked at 69, 166 and 291 degrees C where the more suitable dosimetric maxima appears at higher temperature. It could be observed how the 166 and 291 degrees C TL glow maxima of this material exhibits (i) good linearity in the range of 0.11-15 Gy, (ii) a minimum detectable dose value of 1.11 mGy, (iii) does not modify significantly the TL emission in shape and intensity after reusability (10 cycles) and (iv) a negligible fading effect for 5 Gy irradiated aliquots stored in darkness and room temperature up to 169 h. Additionally, it could be found that (v) kinetic parameters estimated by using variable heating rate method of Hoogenstraaten and initial rise method give similar results.