A latent image of the target after the X‐ray irradiation induced via a 980 nm laser or thermal excitation provides great potentials for healthcare diagnostics and nondestructive inspection. Taking the advantage of X‐ray time‐lapse imaging, simplified facilities and visualized information can be achieved. However, information acquisition with higher resolution, combined with long‐term storage for the corresponding X‐ray images remains a challenge. Herein, Tb3+‐doped Ba2LaF7 nanocrystals (NCs) grown in situ and dispersed uniformly in an amorphous glass matrix is explored, which performs a fascinating X‐ray response for imaging with an impressive spatial resolution reaching 20.0 lp mm−1. Moreover, the as‐developed corresponding scintillators exhibit excellent optical storage capability upon X‐ray irradiation for the constructed deep traps, and a controllable release of the captured carriers induced by thermal disturbance, and 980 nm laser stimulation can be achieved. Notably, the imaging resolution is well preserved to be 20.0 lp mm−1 even recorded after 10 days. The as‐explored Ba2LaF7:Tb3+ NCs embedded within an amorphous matrix realize a feasible approach for a simplified X‐ray imaging system with high‐resolution information production.
Proper
defect states are demonstrated to be beneficial to overcome
thermal quenching of the corresponding phosphors. In this work, a
cyan-emitting KGaGeO4/Bi3+ phosphor with abundant
defect states is reported, the emission intensity of which exhibits
an abnormal thermal quenching performance under excitation with different
photon energies. A 100% emission intensity is achieved at 393 K under
325 nm excitation compared with that at room temperature, while significantly
enhanced intensities of 207% at 393 K and even 351% at 513 K under
365 nm excitation are recorded. The excellent thermal stability performance
is confirmed to be not only related to the direct energy transfer
from the defect states but also depended on the efficiency of capturing
carriers for the trap centers, which is clarified in this work. In
addition, the mechanism of the double tunneling process of carriers
from trap centers to luminescence centers and luminescence centers
to trap centers is studied. These results are believed to provide
new insights into the thermal stability of the corresponding fluorescent
materials and could inspire studies to further explore novel fluorescent
materials with high thermal stability based on defect state engineering.
Real-time stress sensing based on mechanoluminescence materials has been widely studied for structural health monitoring of bridges, buildings, high-pressure vessels, and other infrastructure surfaces. However, this approach is difficult to detect the stress information of closed mechanical structures. Here, we propose a delayed stress memory strategy to record the stress information of closed mechanical structure by the flexible film composed with CaAl2O4:Eu2+,Sm3+ phosphor. After the force is applied, the optical information on the film can be read out by the near-infrared laser after a period of time without real-time monitoring, and the stress distribution information of bearings and gears in the engine can be obtained. Furthermore, the regulation of trap depth from 0.662 to 1.042 eV allows the captured carriers to remain in the traps for a long time without being released as long persistent luminescence, which is beneficial to the delayed stress memory. Therefore, this work promotes the application prospect of mechanoluminescence materials in stress sensing, and provides a new idea to record the stress information of closed mechanical structures.
Organic room-temperature long-persistent luminescent materials are promising light-emitting materials for encryption, architectural decoration, organic solar cells, and biomedical applications. However, their unstable structures and thermal-and humidity-induced emission quenching have greatly limited their utility and reliability. Here, we report a metal-free nonconjugated copolymer that possesses stable photoluminescence at both high temperature and humidity. The room-temperature long-persistent luminescence (LPL) of this copolymer lasts for more than 15 s and can be recovered in high humidity conditions by heating to remove moisture.Copolymer LPL can be achieved with various excitation wavelengths, ranging from ultraviolet to near-infrared, and the LPL color can be adjusted accordingly. The high initial LPL intensity and ultrafast filling time of the copolymer makes it suitable for low flicker alternating current-driven light-emitting diodes (AC-LEDs).
The temperature-dependent optical properties of lanthanide-doped phosphors have been enthusiastically investigated in the fields of biomedicine, night-vision security, and optical information storage. In this work, the dynamically varying temperature-dependent photoluminescence...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.