Thermoluminescent glow curve of Gd 1-x RE x AlO 3 (RE=Dy or Pr) beta irradiated phosphors.

Phosphors composed of Gd _1-x RE _x AlO ₃ (0≤x ≤ 5 RE = Dy or Pr) stoichiometries were synthesized using the reverse coprecipitation pathway. The thermoluminescent responses of all phosphors were studied under beta radiation exposure. Doping the gadolinium aluminate host improved the thermoluminescent response of the phosphors, with the phosphors composed of Gd _0.99 Dy _0.01 AlO ₃ and Gd _0.95 Pr _0.05 AlO ₃ being the most sensitive. The Dy ³⁺ ions produced a higher improvement of the thermoluminescent signal than the Pr ³⁺ ions. Additionally, a proportional relationship between the similarity of the atomic numbers of the dopant and replaced ions and the sensitivity to thermoluminescence was confirmed. Besides, a slight shift of the thermoluminescent peaks toward lower temperatures was detected for doped phosphors. In the repeatability tests applied to the phosphor composed of Gd _0.99 Dy _0.01 AlO ₃ , an anomalous increase in sensitization was observed. The observed sensitization was associated with the formation of electron trap clusters resulting from the continuous exposure to beta radiation. Furthermore, another sensitization phenomenon was detected in the phosphor with Gd _0.95 Pr _0.05 AlO ₃ stoichiometry when it was heated at low temperatures. The aforementioned striking behavior was related to quasi-continuous distributions of electron traps and the tunneling effect. In regard to linearity, the phosphor composed of Gd _0.99 Dy _0.01 AlO ₃ exhibited a linear response with the dose across the entire range of beta doses. However, the response of the Gd _0.95 Pr _0.05 AlO ₃ phosphor lost linearity beyond 26.4 Gy of beta dose. The results obtained through the use of the T _max -T _stop method and deconvolutions suggested an enhancement in the efficiency of the thermoluminescent mechanisms due to the incorporation of activators.
Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Juan Zarate Medina reports financial support was provided by National Council on Science and Technology (CONACYT-MEXICO).
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