Origin of Eu2+/Eu3+ dual-fluorescence emission with temperature-dependency in borate glass containing Ca/SrAl2O4 crystals

At present, due to the existent trap levels, the investigation of the dual-fluorescence emission with temperature-dependency of Eu2+ and Eu3+ in long afterglow materials needs to be supplemented. In this work, Eu2+ and Eu3+ co-doped borate glass materials containing Ca/SrAl2O4 crystals are successfully prepared though solid phase melting method, presenting a temperature-dependent fluorescence emission changing from blue-violet to red-orange between 300 and 500K. This interesting finding is proved to be the different thermal quenching behavior caused by the varied luminescence transition mode of Eu2+ (440 nm) and Eu3+ (614 nm). Further, the instantaneous and the delayed trap carriers release are demonstrated to moderate the thermal quenching behavior, leading to better sensing performance at high temperatures in sample of more trap distribution, with Sr(max) being 1.3535% K−1 at 483K. Finally, good thermal cycling reversibility of the material shows that the temperature-dependent luminescence of Eu2+/Eu3+ assisted by traps is potential for optimizing the application of temperature sensing.