Tailor Traps in Bi<sup>3+</sup>-Doped NaGdGeO<sub>4</sub> Phosphors by Introducing Eu<sup>3+</sup> Ions to Switch Multimodal Phosphorescence Emission
Zhichao Liu, Xue Yu, Xiuxia Yang, Qingpeng Peng, Xiaodie Zhu, Xuhui Xu, Jianbei Qiu
Abstract
Featured with a tunable excitation/emission wavelength and excellent physicochemical stability, inorganic fluorescent materials are widely used in the fields of anti-counterfeiting. Here, we design a multi-stimuli-responsive dynamic fluorescence and phosphorescence anti-counterfeiting material by introducing Eu 3+ ions in NaGdGeO 4: Bi 3+ to tailor the trap structure. The photoluminescence (PL), long persistent luminescence (LPL), and photo-stimulated luminescence (PSL) colors of NaGdGeO 4: Bi 3+, Eu 3+ can be switched by varying the excitation modes (ultraviolet, near infrared, and X-ray light). Especially, the LPL and PSL colors of NaGdGeO 4: Bi 3+, Eu 3+ vary with increasing decay and stimulation times. In addition, X-ray excitation ensures the specificity of the luminescence of NaGdGeO 4: Bi 3+, Eu 3+ compared with ultraviolet excitation. This rapidly-changing-color fluorescent material offers the possibility of sophisticated anti-counterfeiting applications in the future.