A hollow NaBiF₄:Tb nanoscintillator with ultra-weak afterglow for high-resolution X-ray imaging

Compared with commercial bulk scintillators and halide perovskites, lanthanide-doped fluoride nanoscintillators (NSs) exhibit high photochemical stability, low bio-toxicity and tunable emissions. However, the widely employed hosts, such as NaGdF₄, NaLuF₄ and NaYF₄, need many expensive rare earth salts and time-consuming reaction processes. In this work, lanthanide-doped NaBiF₄ NSs were prepared by a facile rapid room-temperature reaction method. The obtained NSs present a hollow structure, strong scintillation intensity and ultra-weak afterglow. The scintillation intensity was enhanced by incorporating Gd³⁺ ions, but it was decreased after codoping with Ho³⁺ or Er³⁺ ions. By employing a NaBiF₄:15Tb/10Gd NS integrated thin film as a nanoscintillator screen, a high spatial resolution of 12.5 lp mm^-1 was achieved. Our results could promote the exploration of new kinds of NSs with low cost, high production and superior performances.