Thermoluminescence properties of La³⁺ , Gd³⁺ ,Dy³⁺ and Ho³⁺ co-doped MgAl₂ Si₂ O₈ :Mn⁴

Thermoluminescence properties of Mn⁴⁺ -doped and La³⁺ , Gd³⁺ , Dy³⁺ and Ho³⁺ co-doped MgAl₂ Si₂ O₈ host phosphors were investigated in detailed and reported for the first time. The phosphors were exposed to β- and α-irradiation and the glow curves appeared at 260-262 ± 2°C and 245-252 ± 2°C, respectively. Thermoluminescence analysis show that the main glow peaks actually consisted of three distinct peaks (P₁ , P₂ and P₃ ). In addition, all the phosphors had a main peak, and many satellite peaks also appeared up to 200°C. Moreover, it was observed that La³⁺ , Gd³⁺ , Dy³⁺ and Ho³⁺ dopants in MgAl₂ Si₂ O₈ Mn⁴⁺ phosphor can change the thermoluminescence peak intensities, but they did not cause any new glow peak. In addition, when α-irradiation was used, the glow peaks were shift to a lower temperature region. Kinetic parameters of P₁ , P₂ and P₃ were calculated, and it was found that P₁ and P₃ had first-order kinetics and P₂ had general-order kinetic parameters. In addition, it was found that when the easy and convenient annealing procedure was applied to the phosphorus, the thermoluminescence signal was measured as stable over many repetitions. The dose sensitivity, reproducibility and fading features of the powdered phosphors were investigated and computerized glow curve deconvolution analysis was also performed. Results showed that thermoluminescence properties of these materials were good but the fading reliabilities were poor and therefore the sintered or single crystal forms should be preferred for their better fading properties.