Radiation‐Stored Double Perovskites Framed by Local Symmetry Disruption for Thermal‐Functional X‐Ray Tomographic Imaging

ABSTRACT Owing to their unique radiation‐stored thermoluminescence behavior, double perovskite scintillators offer a novel and promising route for highprecision nondestructive inspection. However, the intrinsic structural origin and physical nature of this phenomenon remain unclear. In this work, we employ a high‐structural‐tolerance double perovskite, Cs 2 NaScCl 6 , as a model and propose localized site engineering to modulate the structural symmetry and energy transfer. The broadband performance, covering the intrinsic emission and Sm 3+ ‐induced near‐infrared luminescence, was tuned by Ag + doping to obtain a temperature‐dependent luminescence behavior. Interestingly, the formation of trap levels for radiation storage was revealed, with enhanced thermoluminescence performance and dramatically lengthened lifetimes. Theoretical calculations revealed that local symmetry disruption of the lattice structure and electron density originated from octahedral distortion of [AgCl 6 ] 5− and an electron localization hotspot around Ag–Cl coordination regions. Because of the trap levels contributed by the Ag + , which offered an extra path for radiation storage and thermal release, Cs 2 NaScCl 6 :Sm,Ag exhibited thermally enhanced performance and outstanding high‐temperature radiation stability. Furthermore, a thermally functional film‐based device featuring direct/indirect dual‐mode thermally driven imaging enhancement was fabricated to perform 3D tomographic scanning of industrial chips. The results demonstrate that the site‐regulated local symmetry strategy provides new material design perspectives for next‐generation X‐ray imaging technologies.