Stable CsLu ₂ F ₇ :Tb/Eu Nanocrystal Scintillators for High‐Resolution X‐Ray Imaging

Abstract X‐ray imaging holds great promise in medical diagnosis, industrial nondestructive examination, and security screening. However, developing scintillators that simultaneously achieve high spatial resolution and long‐term operational stability remains a significant challenge. Herein, Tb ³⁺ ‐ and Eu ³⁺ ‐doped small‐sized CsLu ₂ F ₇ (CLF) nanocrystal scintillators are reported. The high atomic numbers of Cs and Lu enhance X‐ray attenuation, while nanocrystal dimensions minimize light scattering, enabling the fabrication of transparent, thin scintillator films with efficient X‐ray interaction. The nanocrystals exhibit green (Tb ³ ⁺) or red (Eu ³ ⁺) emission, and demonstrate a low detectable dose rate of 0.48 µGy s ⁻¹ for Tb ³ ⁺ doped CLF. Importantly, the nanocrystal scintillators possess excellent long‐term stability against high‐dose X‐ray irradiation, humidity, and elevated temperature. Incorporation of nanocrystals into waterborne polyurethane (PU), CLF‐25%Tb@PU films, yields a high spatial resolution of 30 lp mm ⁻¹ and a film thickness of ≈ 200 µm. Notably, these films enable high‐contrast 2D projection imaging of various objects. These results highlight the great potential of as‐prepared scintillators in X‐ray imaging applications.