Temperature dependence of persistent luminescence in CaAl2O4:Eu2+, Nd3+ related to beta irradiation and optical excitation

Mechanisms responsible for the emission of persistent luminescence in CaAl2O4:Eu2+, Nd3+ are typically studied following excitation by ultraviolet or visible light. In contrast, we have studied the persistent luminescence from this material after beta irradiation and optical excitation. These studies have been carried out at 25 degrees C as well as at various temperatures up to 100 degrees C. A thermoluminescence (TL) glow curve measured at 1 degrees C/s following beta irradiation showed a glow peak at 63 degrees C. On the other hand, a glow curve measured after 15 s of optical excitation by polychromatic white light shows a peak at 102 degrees C. The partial heating procedure reveals that each of the TL peaks consist of several overlapping components. The TL in each case was analysed for kinetic parameters. The initial rise analysis carried out on the rising edge of the overlapping components shows that the activation energy of the component peaks corresponding to beta irradiation is consistent at (0.59 +/- 0.01) eV. In comparison, activation energies corresponding to optical excitation increases with the partial heating temperature from (0.71 +/- 0.01) eV to (0.76 +/- 0.01) eV. The activation energy of (0.59 +/- 0.01) eV is ascribed to an oxygen vacancy whereas the range of activation energies between (0.71 +/- 0.01) eV and (0.76 +/- 0.01) eV is ascribed to the 4 f levels of the Nd dopant.