Development of Ce3+ and Li+ co-doped magnesium borate glass ceramics for optically stimulated luminescence dosimetry

Abstract

Magnesium tetraborate, MgB4O7, is an attractive host material for dosimetry due to the two characteristics: its low effective atomic number (Zeff = 8.4) and high neutron capture cross-section of the 10B isotope. Particularly, Ce3+ and Li+ ions co-doped MgB4O7 has shown optically stimulated luminescence (OSL) signal comparable to that of Al2O3:C, which is a well-known OSL dosimetry material. In this work, for further improvement of the dosimetric properties, a new synthesis route for MgB4O7:Ce3+-Li+ is described: glass-ceramic (GC) MgB4O7:Ce3+-Li+ samples were prepared by heat treatment of the magnesium borate glass with the composition, 25MgO–72B2O3–3Li2O-0.3Ce3+. The prepared GC samples show UV-blue radioluminescence assigned to the Ce3+ 5d → 4f transition under X-ray irradiation and two thermoluminescence (TL) glow peaks related to the shallow and deep electron traps. Although fading of the TL and OSL signal was observed due to electron release from the shallow traps, the electrons captured by deep traps were stable at room temperature. Particularly, GC samples annealed at 750 °C and 800 °C, named GC750 and GC800, showed stable OSL up to 10 h following β-ray irradiation, after an initial fading mainly due to the presence of shallow traps in the material. From the viewpoint of this fading ratio, GC750 and GC800 showed potential as a practical OSL dosimeter.