Flexible scintillation films based on Ni Co-doped LiLuF4:Tb for high-resolution X-ray and thermoluminescence dual-mode imaging

Abstract

LiLuF₄ microcrystalline scintillation materials possess several advantages, including high chemical stability, simplified fabrication processes, and tunable emission wavelengths. These materials demonstrate significant potential in fields such as X-ray imaging, biodiagnostics, photodynamic therapy, advanced anti-counterfeiting, and thermally activated delayed imaging. However, the relatively weak radioluminescence intensity of single rare-earth-doped LiLuF₄ crystals has constrained their practical applications. In this work, Ni²⁺ co-doped LiLuF₄:Tb microcrystalline scintillators are synthesized via a hydrothermal method. The incorporation of heterovalent Ni²⁺ ions effectively enhanced both the radioluminescence and thermoluminescence intensities of LiLuF₄ microcrystals. After doping with 3 mol% Ni²⁺ ions, the radioluminescence intensity increased by 125.34%. The X-ray detection limit of LiLuF₄:Tb,Ni reaches 3.7966 nGy s⁻¹, which is considerably lower than the medical imaging requirement of 5.5 μGy s⁻¹. Furthermore, a large-area flexible composite scintillation film of dimensions 80 mm × 145 mm was prepared to achieve high-spatial-resolution X-ray imaging of 25 LP mm⁻¹@20% MTF, indicating that heterovalent-doped fluoride scintillators possess exceptional application potential.