A Thermally Stable Eu ²⁺ ‐Doped Glass‐Ceramic for High‐Resolution X‐Ray Imaging and Full‐Spectrum Lighting

Luminescent glass‐ceramic (GC) materials are emerging candidates as scintillators for X‐ray imaging and light emitters for white light‐emitting diodes (WLEDs). However, designing a thermally stable GC with appropriate performance for multiscenario applications remains a challenge. Herein, a novel multifunctional GC containing Gd 0.8 Ca 0.2 F 2.8 :Eu 2+ nanocrystals was prepared based on three strategies, including Gd 3+ sensitization, controllable crystallization, and a dual‐reduction synthesis. The optimal GC achieves high crystallinity (30.4%) and high transparency (83.8% at 430 nm). For scintillating performance, GC exhibits high X‐ray‐excited luminescence (XEL) intensity (98% of Bi 4 Ge 3 O 12 ), high spatial resolution of 17.5 lp mm −1 , and a low detection limit of 2.2 µGy s −1 . The XEL intensity of GC at 513 K reaches 80% of that at 303 K, facilitating its successful application in high‐temperature X‐ray imaging. By increasing the content of Gd 0.8 Ca 0.2 F 2.8 :Eu 2+ nanocrystals, the GC powder achieves outstanding thermal stability in photoluminescence, retaining 83% of its initial intensity at 423 K. Full‐spectrum WLED devices based on the GC powder and commercial phosphors are developed, demonstrating a high color rendering index of 96.4. This work expands the scope of fluoride phases inside a transparent amorphous medium and paves the way toward the implementation of high‐temperature X‐ray imaging and high‐quality lighting of GC materials.