Synthesis of Samarium‐incorporated X‐ray‐sensitive nanoparticles and hydrogels: Diverse applications in radiation monitoring and dynamic information display

Abstract With the advancement of X‐ray‐activated persistent luminescent phosphors, the exploration of smart materials with tunable luminescence and afterglow properties is a promising topic. In this study, the red‐emission X‐ray scintillators, Samarium(Sm 3+ )‐doped NaLuF 4 , with regular micromorphology and well‐controlled afterglow property were synthesized under mild conditions. Both of Sm 3+ ‐doped α ‐NaLuF 4 and β ‐NaLuF 4 , abbreviated as α ‐NaLuF 4 : x Sm 3+ and β ‐NaLuF 4 : y Sm 3+ ( x , y = 1, 3%, 5%, 10%, and 15%), respectively, emit the maximum emission peak at 598 nm (4G 5/2 → 6H 7/2 ) under X‐rays, while only Sm 3+ ‐doped β ‐NaLuF 4 exhibits remarkable afterglow ability. The optimal luminescent property can be obtained when the doping rate is fixed at 3%. Then β ‐NaLuF 4 :3%Sm 3+ was surface modified and incorporated into the chemically crosslinked hydrogels to endow X‐ray‐activated luminescence or afterglow abilities in the obtained hybrid hydrogel. With the self‐healing ability, the β ‐NaLuF 4 :3%Sm 3+ ‐incorporated hydrogel can be further programmed with other types of hydrogels to enable tunable emission behaviors and time‐dependent color changes. By taking advantage of these features, the hydrogels were programmed as a display panel that can be used for extra safety information encryption.