Terbium doped LiLuF₄ nanocrystal scintillator-based flexible composite film for high resolution X-ray imaging

Radiographic screens are widely used in high energy physics, national defense, aviation, radiodynamic therapy and medical imaging due to their scintillation materials that can transform high-energy particles or rays into ultraviolet (UV) visible light or other signals. In recent years, lanthanide doped fluoride nanocrystals (NCs) have attracted much attention due to their excellent optical properties and stability. In this work, multiple lanthanide-doped LiLuF₄ nanocrystal scintillation materials were synthesized by thermal decomposition. Among them, Tb-doped LiLuF₄ nanocrystals have high X-ray sensitivity and low detection limit (36.31 nGy s^-1), which is much lower than the requirement of medical imaging dose rate. After the irradiation of 42.29 mGy s^-1 X-ray for 1 hour, the intensity of radioluminescence basically remained unchanged. Based on the good properties of our nanocrystals, we further prepared the flexible film of nanocomposites with epoxy resin. This kind of uniform, large area, high loaded flexible film exhibits excellent performance in X-ray imaging with a spatial resolution greater than 20 line pairs per millimeter (LP/mm).