High‐Temperature X‐Ray Imaging Based on a Thermal Quenching‐Resistant YAG:Ce ³⁺ Transparent Glass Scintillator

Realizing high‐spatial‐resolution x‐ray imaging under extreme thermal conditions, critical for aerospace diagnostics and industrial inspection, remains challenging due to severe non‐radiative thermal quenching in conventional scintillators. Herein, we report a thermally robust Y 3 Al 5 O 12 :Ce 3+ (YAG:Ce 3+ ) phosphor‐in‐glass (PiG) scintillator fabricated via a streamlined co‐sintering protocol that overcomes the processing complexity and cost limitations of transparent ceramics. The optimized PiG scintillator achieves a competitive light yield of 21,934 photons MeV −1 while retaining 72% of its initial radioluminescence (RL) intensity at 483 K, significantly surpassing commercial Bi 4 Ge 3 O 12 (BGO) and Cesium iodide doped with thallium (CsI:Tl) standards. Mechanistic investigations reveal that trap levels compensate for non‐radiative losses at elevated temperatures through a thermally assisted charge‐recycling process. Combining a fast fluorescence decay (68.72 ns), a low detection limit (79.91 µGy s −1 ), and exceptional thermal robustness, this scintillator enables in situ, high‐fidelity dynamic imaging of phase transitions in molten tin, with high spatial resolution well retained even at 483 K (from 15.05 to 11.05 lp mm −1 ). This work establishes a defect‐engineering paradigm for next‐generation anti‐thermal‐quenching scintillators that can be deployed in extreme thermal environments.