The thermally connected traps model applied to the thermoluminescence of Eu2+ doped Ba13-xAl22-2xSi10+2xO66 materials (x0.6)

The thermoluminescence (TL) properties of the Eu 2+ doped Ba13-xAl22-2xSi10+2xO66 (x0.6) phosphorescent materials (hereafter labeled BASO:Eu) are analyzed on the basis of the thermally connected traps (TCT) model. Basically, in these materials, Eu 2+ cations are photo-ionized under UV excitation, and electrons are trapped at defects. The return to the ground state is thermo-stimulated, and the freed electrons recombine at photo-oxidized activator sites with emission of light. TL properties between 80 and 650 K, as well as an isothermal emission decay (IED) at room temperature, were collected for BASO:Eu1% and BASO:Eu0.5% samples to characterize the phosphorescence mechanism in this series of materials and to determine the trap depths. Thermoluminescence glow curves of BASO:Eu excited either at 254 nm or at 365 nm, or excited at 254 nm for durations of 10 s and 240 s, as well as the IED, agree well with a TCT model. Based on our analysis, phosphorescence in BASO:Eu compounds is associated with the depletion of five traps with depths of 0.56, 0.61, 0.65, 0.69 and 0.73 eV.