Precision X‐Ray Time‐Lapse Flexible Imaging from Fluoride Nanocrystals with the Constructed Deep Traps

Abstract

X‐ray time‐lapse imaging allows for precise radiographic imaging of the item after X‐ray has been terminated, which is important for simplifying legacy X‐ray detectors and avoiding health hazards caused by ionizing radiation during the imaging process. However, the premature discharge of carriers from shallow traps at room temperature over time leads to the loss of imaging information, making an accurate representation of the recorded information to achieve accurate time‐lapse imaging still a challenge. Here, it is demonstrated that monodispersed NaLuF4: Tb3+ nanocrystals with the replacement of Na+ by Cs+ ions in the lattice matrix realize a superior X‐ray time‐lapse imaging. It is found that the incorporation of Cs+ ions amplifies the deep trap storage capacity, which ensures the stable presence of carriers under thermal perturbation at room temperature. Imaging information with a spatial resolution of 12.0 lp mm−1 can be accurately represented even after the irradiation of the X‐ray has been terminated for 192 h. X‐ray time‐lapse imaging not only allows accurate reading of long‐term stored imaging information but also endows the visualization of X‐ray imaging independent of the dangerous radiation, which will offer great opportunities for X‐ray inspection on a larger scale.

Enhanced Storage Capacity via Anion Substitution for Advanced Delayed X-ray Detection

“…23 Considering the lattice mismatch caused by the substitution of Br − and I − ions for F − ions, it is speculated that the lattice mismatch could potentially introduce more detects and even create defect pairs with sufficient distance serving as deep traps. 26 Moreover, the release process of trapped electrons also plays an important role in trap-dependent luminescence behaviors. Here, the projected density of states (DOS) and optical leap energies are calculated based on density functional theory (DFT) in Figure 4b−d.…”

“…However, there are still significant problems in addressing the loss of irradiation information after the X-ray-induced afterglow disappears due to the lack of means to regulate radiation traps. Notably, Peng et al demonstrate a substitution strategy of Cs + for Na + ions to increase the storage capacity of deep traps, where the stored information can be read out accurately even 196 h after the cessation of X-rays, exhibiting excellent stability of X-ray storage . Nevertheless, further development is still needed to enhance the X-ray storage capacity of fluoride nanocrystals in order to meet the requirements of diverse application scenarios.…”

“…The distance between the Frenkel defect pairs determines the depth of the trap state . Considering the lattice mismatch caused by the substitution of Br – and I – ions for F – ions, it is speculated that the lattice mismatch could potentially introduce more detects and even create defect pairs with sufficient distance serving as deep traps . Moreover, the release process of trapped electrons also plays an important role in trap-dependent luminescence behaviors.…”