High‐Entropy Lead‐Free Relaxor Ferroelectric Ceramic with Wide‐Temperature‐Range Self‐Powered X‐Ray Detection

ABSTRACT Sensitive and stable x‑ray detectors are essential for low‑dose medical diagnostics. Achieving wide‑temperature operation in materials remains a key challenge for enabling thermally stable, self‐powered x‑ray detection. Herein, a high‐entropy lead‐free relaxor ferroelectric ceramic, 0.85Bi 0.47 Na 0.47 Ba 0.06 TiO 3 ‐0.15Ca 0.7 Ho 0.2 Ti 0.75 Ta 0.2 O 3 (BNBT‐CHTT), is fabricated first. The unique entropy‐stabilized polar nanoregions (PNRs) endow the system with high resistivity and robust spontaneous polarization, underpinning exceptional self‐powered performance across a broad thermal window. Under 70 keV x‐ray irradiation, the detector exhibits excellent stability from 25°C to 185°C, delivering record‐high specific sensitivities of 1117.44–1223.55 µC Gy air −1 cm −2 , self‐powered sensitivities of 597.28–699.78 µC Gy air −1 cm −2 , and low detection limits of 38.7–160.6 nGy a i r s −1 . Notably, distortion‐free x‐ray imaging is demonstrated at 185°C under zero bias, validating the material's practical utility. This work highlights the potential of high‐entropy relaxor ferroelectrics to overcome key limitations of existing detectors and provides a robust platform for next‐generation, low‐power, wide‐temperature‐range x‐ray detection and imaging technologies.