Metal Halide Nanocrystals@Silica Aerogel Composite with Enhanced Dispersion Stability and Light Output for Efficient X-Ray Imaging in Harsh Environment

Metal halide nanocrystals (MHNCs) embedded in a polymer matrix as flexible X-ray detector screens is an effective strategy with the advantages of low cost, facile preparation, and large area flexibility. However, MHNCs easily aggregate during preparation, recombination, under mechanical force, storage, or high operating temperature. Meanwhile, it shows an unmatched refractive index with polymer, resulting in low light yield. The related stability and properties of the device remain a huge unrevealed challenge. Herein, a composite screen (CZBM@AG-PS) by integrating MHNCs (Cs2ZnBr4: Mn2+ as an example) into silica aerogel (AG) and embedded in polystyrene (PS) is successfully developed. Further characterization points to the high porosity AG template that can effectively improve the dispersion of MHNCs in polymer detector screens, essentially decreasing nonradiative transition, Rayleigh scattering, and performance aging induced by aggregation in harsh environments. Furthermore, the higher light output and lower optical crosstalk are also achieved by a novel light propagation path based on the MHNCs/AG and AG/PS interfaces. Finally, the optimized CZBM@AG-PS screen shows much enhanced light yield, spatial resolution, and temperature stability. Significantly, the strategy is proven universal by the performance tests of other MHNCs embedded composite films for ultra-stable and efficient X-ray imaging.

Photoluminescent and Scintillating Performance of Eu3+-Doped Boroaluminosilicate Glass Scintillators

In comparison with single crystal scintillators, glass scintillators are more promising materials for their benefits of easy preparation, low cost, controllable size, and large-scale manufacture. The emission of Eu³⁺ ion at 612 nm matches well with the photoelectric detector, making it suitable for the activator in glass scintillators. Therefore, the research on Eu³⁺ doped glass scintillators attract our attention. The photoluminescent and scintillating properties of Eu³⁺-activated boroaluminosilicate glass scintillators prepared by the conventional melt-quenching method were investigated in this work. The glass samples present good internal quantum yield. Under X-ray radiation, the optimal sample reveals high X-ray excited luminesce (XEL), and its integrated intensity of XEL is 22.7% of that of commercial crystal scintillator Bi₄Ge₃O₁₂. Furthermore, the optimal specimen possesses a spatial resolution of 14 lp/mm in X-ray imaging. These results suggest that Eu³⁺-doped boroaluminosilicate glass is expected to be applied in X-ray imaging.

Visualization of X-rays with an Ultralow Detection Limit via Zero-Dimensional Perovskite Scintillators

X-rays play an extremely significant role in medical diagnosis, safety testing, scientific research, and other practical applications. However, as the main sources of radioactive pollution, the hazard of X-rays to human health and the environment has been a major concern. Herein, the explored perovskite scintillator of Cs₂Zr_1-xPb_xCl₆ in this work exhibits an ultrahigh radioluminescence intensity owing to the enhanced X-ray absorption for the introduction of Pb²⁺ ions. The Cs₂Zr_1-xPb_xCl₆ crystals are demonstrated as efficient scintillators with a self-trapped exciton emission and extremely high steady-state light yield (∼101,944 photons meV^-1). This fascinating scintillator provides a convenient visual tool for X-ray detection even for an indoor lighting environment, reaching a low detection limit of ∼14.2 nGy·s^-1, which is about 1/387 of the typical medical imaging dose (5.5 μGy·s^-1). Moreover, X-ray imaging with a high resolution of 16.6 lp·mm^-1 is achieved with the as-explored Cs₂Zr_1-xPb_xCl₆ scintillator film. Herein, the Cs₂Zr_1-xPb_xCl₆ scintillator provides a feasible strategy for X-ray monitoring in the field of biomedicine, high-energy physics, national security, and other applications.