Bright Transparent Scintillators with High Fraction BaCl 2 : Eu 2+ Nanocrystals Precipitation: An Ionic-Covalent Hybrid Network Strategy toward Superior X-Ray Imaging Glass-Ceramics.

Metal halide crystals are bright but hygroscopic scintillator materials that are widely used in X-ray imaging and detectors. Precipitating them in situ in glass to form glass ceramics (GCs) scintillator offers an efficient avenue for large-scale preparation, high spatial resolution, and excellent stability. However, precipitating a high fraction of metal halide nanocrystals in glass to maintain high light yield remains a challenge. Herein, an ionic-covalent hybrid network strategy for constructing GCs scintillator with high crystallinity (up to ≈37%) of BaCl 2 : Eu 2+ nanocrystals is presented. Experimental data and simulations of glass structure reveal that the Ba 2+ -Cl - clustering promotes the high crystallization of BaCl 2 nanocrystals. The ultralow phonon energy (≈200 cm -1 ) of BaCl 2 nanocrystals and good Eu reduction effect enable high photoluminescence inter quantum efficiency (≈80.41%) in GC. GCs with varied crystallinity of BaCl 2 : Eu 2+ nanocrystals demonstrate efficient radioluminescence and tunable scintillator performance. They either outperform Bi 4 Ge 3 O 14 single crystal by over 132% steady-state light yield or provide impressive X-ray imaging resolutions of 20 lp mm -1 . These findings provide a new design strategy for developing bright transparent GCs scintillators with a high fraction of metal halide nanocrystals for X-ray high-resolution imaging applications.