Enhancing light yield of Tb3+-doped fluoride nanoscintillator with restricted positive hysteresis for low-dose high-resolution X-ray imaging

Developing scintillators with high light yield (LY), superior irradiation stability, and weak afterglow is of significance for the realization of low-dose high-resolution X-ray excited optical luminescence (XEOL) imaging. Lanthanide doped fluoride nanoparticles possess low toxicity, superior environmental stability, facial fabrication process, and tunable emissions, which are appropriate candidates for the next generation nanoscintillators (NSs). However, the low LY and strong positive hysteresis greatly restrict their practical application. Here, we propose an effective strategy that engineers energy gap to significantly enhance the LY. Our results verify that the tetragonal LiLuF4 host benefits the crystal level splitting of Tb3+ ions, which greatly promotes the electrons population on the Tb3+:D-5(4) level followed by the enhanced LY. The LY of LiLuF4:Tb@LiLuF4 NSs is calculated to be similar to 31,169 photons/MeV, which is much higher than the lead halide perovskite colloidal CsPbBr3 (similar to 21,000 photons/MeV) and LuAG:Ce (similar to 22,000 photons/MeV) scintillators. Moreover, the positive hysteresis is remarkably restricted after coating a thin shell. The X-ray detection limit and spatial resolution are measured to be similar to 21.27 nGy/s and similar to 7.2 lp/mm, respectively. We further verify that this core/shell NS can be employed as scintillating screen to realize XEOL imaging under the low dose rate of 13.86 mu Gy/s. Our results provide an effective route to develop high performance NSs, which will promote great opportunities for the development of low-dose high-resolution XEOL imaging devices.

Automated summary

In this study, an effective strategy to enhance the light yield of nanoscintillators (NSs) by engineering the energy gap was proposed. The results demonstrated that the engineered LiLuF4:Tb@LiLuF4 NSs exhibited high light yield and enabled high-resolution X-ray excited optical luminescence (XEOL) imaging at low dose rates.