Design of the persistent luminescence colour of a novel Gd3−xTbxGa3Al2O12 phosphor: synthesis methods, spectroscopic properties and mechanism

Abstract

The aim of this work was to check the influence of Tb³⁺ ion concentration and synthesis method on the persistent luminescence properties. A series of Gd_3−xTb_xGa₃Al₂O₁₂ 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 Tb³⁺ doping level. The spectroscopic measurements show that persistent luminescence appears only under UV excitation, suggesting that the 5d levels of Tb³⁺ 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.