White light emission, quantum cutting, and afterglow luminescence of Eu3+-doped Ba5Gd8Zn4O21

Ba5Gd8Zn4O21:xEu3+ (x = 0.05%, 0.5%, 1%, 2%, 5%, and 10%) phosphors were prepared by a conventional high-temperature solid-state reaction. White light emission was generated by the combined 5D0,1,2,3-7F0,1,2,3 transitions of Eu3+ in Ba5Gd8Zn4O21 under 395 nm excitation. More interestingly, when the same phosphor was excited by ultraviolet (274 nm) and X-ray, the intense red emission were achieved and it is interpreted by efficient quantum cutting between Gd3+ and Eu3+. The cutting efficiency of Ba5Gd8Zn4O21:1%Eu3+ was calculated to be around 169% under X-ray excitation. Furthermore, after X-ray irradiation, the phosphors showed an intense long-lived afterglow luminescence and the luminescence can be modulated via sintering temperature.