Modulating Deep Trap in Persistent Luminescent CaSb ₂ O ₆ via In Doping for High Temperature and Delayed X‐Ray Imaging

Delayed x‐ray imaging based on storage phosphors enables spatial and temporal separation of exposure and readout, offering advantages over conventional scintillators in complex environments. However, oxide phosphors with high storage capacity and tunable deep traps remain limited. Here, we report In‐doped CaSb 2 O 6 as a robust oxide storage phosphor with engineered deep traps for high‐temperature and delayed x‐ray imaging. In substitution introduces charge‐compensating defects significantly increasing trap depth and density. The optimized CaSb 2 O 6 :0.4%In exhibits enhanced persistent luminescence lasting over 20 h and stable retention of detectable trapped carriers exceeding 30 days. Remarkably, anti‐thermal quenching behavior enables luminescence intensity at 433 K to reach 3.7 times that at room temperature, supporting high‐temperature operation. The phosphor demonstrates linear x‐ray dose response, excellent radiation stability, and repeatable write‐store‐read cycles. Flexible composite films fabricated from the material enable conformal imaging and delayed thermal readout. Using this platform, we demonstrate high‐resolution flexible x‐ray imaging and a proof‐of‐concept for conformal x‐ray imaging of 3D objects. This work establishes trap engineering in antimonate phosphors as an effective route toward stable, flexible, and high‐performance x‐ray storage and imaging systems.