Atmosphere-Controlled Valence Engineering of Eu in Aluminate Crystals Enabling High-Performance Temperature Sensing and Flexible X-Ray Imaging.

Developing scintillators that simultaneously deliver high light yield, radiation stability, flexibility, and environmental sustainability remains a long-standing challenge, while optical thermometry is further limited by narrow working ranges and insufficient sensitivity. Here, we propose a buried-carbon reduction concept that enables precise regulation of Eu valence states through controlled carbon burial depth from a single precursor, thereby unlocking multifunctionality within one material system. By such strategy, fully reduced SrMgAl10O17:Eu2+ is utilized in x-ray detection and imaging. High-energy irradiation activates defect-mediated electron release, substantially increasing the effective concentration of luminescent centers. Remarkably, its radioluminescence intensity retains 117.5% after over 150 on-off irradiation cycles, showing a long-term working light yield of up to 55917 ± 573 photons MeV-1, together with excellent linear dose response and a low detection limit. Flexible scintillator films achieve a spatial resolution of 11.7 lp mm-1(at 20% MTF). These characteristic makes the material with low cost, flexibility, environmental protection, chemically stable, and excellent radiation resistance. Moreover, partially reduced SrMgAl10O17:Eu2+/Eu3+ exhibits rare multimodal synergistic optical thermometry performance in the high-temperature region owing to distinct thermal quenching behaviors. In the temperature range of 550-625 K, the FIR-based Sa and Sr reach 0.226 K-1 and 0.97 %K-1, respectively; the FWHM-based thermometric mode achieves a maximum sensitivity of 0.238 nm/K, while also enabling visual discrimination of the temperature. This work establishes a versatile concept for designing advanced optical materials for radiation detection and temperature sensing.