X-ray-irradiation-induced photoluminescence and photochromic LiNbO3 phosphors for anti-counterfeiting and X-ray imaging†

This study explored the innovative photochromic and photoluminescence properties of Eu³⁺-doped LiNbO₃ phosphors under X-ray irradiation, demonstrating their great potential for anti-counterfeiting, X-ray detection and imaging. The photochromic phosphor LiNbO₃:Eu³⁺ is synthesized, which undergoes a color change from white to brown under bright field conditions and displays red photoluminescence under dark field conditions after X-ray exposure due to defect formation. The addition of Eu³⁺ enhanced the photochromic reaction and rapid self-bleaching ability. The study delved into the mechanisms of photochromic and photoluminescence behavior, focusing on electron–hole pair separation and defect formation, which are central to the observed phenomena. In addition, the integration of these phosphors into polydimethylsiloxane can create multifunctional anti-counterfeiting labels and can also be used for “dual-mode” 3D X-ray imaging and detection, showing practical application potential.