Design of the persistent luminescence colour of a novel GdTbGaAlO phosphor: synthesis methods, spectroscopic properties and mechanism.

The aim of this work was to check the influence of Tb ion concentration and synthesis method on the persistent luminescence properties. A series of GdTbGaAlO nanopowders were obtained by using two different synthesis methods. The crystal structure refinement was performed to check the impact of the preparation method and doping level on the crystallization process. This revealed the influence of doping level on conventional and persistent luminescence color, intensity and decay time. It was demonstrated that it is possible to tune the persistent luminescence color by changing the Tb doping level. The spectroscopic measurements show that persistent luminescence appears only under UV excitation, suggesting that the 5d levels of Tb play an active role in this process. Thermoluminescence measurements indicate that the depth and number of electron traps in the samples are associated with the synthesis method and dopant concentration. Based on the results, the possible mechanism of energy transfer between the traps and luminescence centers is proposed and discussed.