Thermoluminescence properties of La3+, Gd3+, Dy3+ and Ho3+ co-doped MgAl2Si2O8:Mn4+

Thermoluminescence properties of Mn4+-doped and La3+, Gd3+, Dy3+ and Ho3+ co-doped MgAl2Si2O8 host phosphors were investigated in detailed and reported for the first time. The phosphors were exposed to beta- Dand alpha-irradiation and the glow curves appeared at 260-262 +/- 2 degrees C and 245-252 +/- 2 degrees C, respectively. Thermoluminescence analysis show that the main glow peaks actually consisted of three distinct peaks (P-1, P-2 and P-3). In addition, all the phosphors had a main peak, and many satellite peaks also appeared up to 200 degrees C. Moreover, it was observed that La3+, Gd3+, Dy3+ and Ho3+ dopants in MgAl2Si2O8Mn4+ phosphor can change the thermoluminescence peak intensities, but they did not cause any new glow peak. In addition, when alpha-irradiation was used, the glow peaks were shift to a lower temperature region. Kinetic parameters of P-1, P-2 and P-3 were calculated, and it was found that P-1 and P-3 had first-order kinetics and P-2 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.