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

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(Sm3+)-doped NaLuF4, with regular micromorphology and well-controlled afterglow property were synthesized under mild conditions. Both of Sm3+-doped α-NaLuF4 and β-NaLuF4, abbreviated as α-NaLuF4:xSm3+ and β-NaLuF4:ySm3+ (x, y = 1, 3%, 5%, 10%, and 15%), respectively, emit the maximum emission peak at 598 nm (4G5/2 → 6H7/2) under X-rays, while only Sm3+-doped β-NaLuF4 exhibits remarkable afterglow ability. The optimal luminescent property can be obtained when the doping rate is fixed at 3%. Then β-NaLuF4:3%Sm3+ 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-NaLuF4:3%Sm3+-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.