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

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_0.47Na_0.47Ba_0.06TiO₃-0.15Ca_0.7Ho_0.2Ti_0.75Ta_0.2O₃ (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.