Thermoluminescence study of aluminum oxide doped with therbium and thulium

In this work, α-Al2O3 doped either with Tb3+ or Tm3+ was prepared by combustion synthesis techniques for thermoluminescent (TL) ionizing radiation dosimetry applications. In this method, the reactants (aluminum nitrate, urea and therbium or thulium nitrate) are ignited in a muffle furnace at temperatures as low as 500 oC. This synthesis route is an alternative technique to the conventional fabrication methods of materials based on α-Al2O3 (Czochralsky, Vernuil), where high melting temperatures and reducing atmospheres are required. After combustion, the samples were annealed at temperatures ranging from 1000 to 1400 oC for 4 h in order to obtain the pure α-phase structure and were then irradiated with a Co-60 gamma radiation source. The annealed samples present a well defined TL glow peak with a maximum at approximately 200 oC and linear TL response in the dose range 0.5-5 Gy. It was observed that a 0.1 mol% concentration of Tb3+ or Tm3+ and annealing at 1400 oC optimize the TL sensitivity. The highest sensitivity was found for Tm3+ doped samples which were approximately 25 times more sensitive than Tb3+ doped samples. These results strongly suggest that combustion synthesis is a suitable technique to prepare doped aluminum oxide material and that Tm3+ doped aluminum oxide is a potential material for TL radiation dosimetry.