ZnO modified with Tm₂O₃ as a possible material for ionizing radiation dosimetry

Based on its chemical stability, radiation hardness, and thermoluminescent response characteristics, ZnO has been shown to be a promising phosphor for the development of high-performance radiation dosimeters. Its thermoluminescence (Tl) can be improved by doping with rare earths. In this work, the synthesis of ZnO:Tm is reported by a chemical method of controlled precipitation and mechanical grinding using a planetary ball mill. X-ray diffraction (XRD) of the samples revealed the hexagonal structure of the zincite phase of ZnO. Images obtained by scanning electron microscopy (Sem) show that the material particles have a hemispherical morphology. The brightness curves of the ZnO:Tm samples show greater reusability than those of ZnO in repeated cycles of irradiation - Tl reading. ZnO:Tm did not show significant shifts in the position of Tl maxima compared to ZnO. The integrated Tl of ZnO:Tm exhibits a linear dependence on the dose from 1.0 to 8.0 Gy of beta particle irradiation; Furthermore, its brightness curve exhibits three main maxima, two with first-order kinetics at ~144 °C and ~342 °C and one of second order whose maximum moves from ~277 °C to ~261 °C as the dose increases. McKeever experiments suggest that the brightness curve of the synthesized ZnO:Tm results from the superposition of at least three individual Tl peaks with maxima in the temperature range of interest for applications in thermoluminescent dosimetry. (author)