Sm³⁺-activated zirconate ceramics: multimodal self-calibrating photothermal feedback window for nuclear environments

Next-generation nuclear energy systems demand advanced radiation shielding windows with precise optical thermometry, while existing photothermal feedback windows that rely solely on fluorescence intensity ratio (FIR) exhibit insufficient accuracy and lack self-calibration. To address this, a novel multimodal self-calibrating photothermal feedback window using Sm³⁺-doped Y₂Zr₂O₇ (YZO) highly transparent ceramics is developed. Three luminescence thermometry modes, FIR, valley-to-peak ratio (VPR), and full-width-at-half-maximum (FWHM), are employed for temperature quantification. The developed ceramic window exhibits excellent sensitivity, with maximum Sr up to 0.518%K-1 and high repeatability (>99.4%) from 303 to 573 K. Notably, the VPR and FWHM modes demonstrate higher thermometric sensitivity and enhanced stability compared to the conventional FIR method. Furthermore, the self-calibration property provided by three modes overcomes the limitations of a single one, thus improving measurement reliability. These results not only indicate YZO:Sm ceramics as a robust thermometric window for nuclear environments but also provide a reference for engineering radiation-shielding, self-calibrating photothermal feedback windows.