Defect elimination to enhance photoluminescence and optical transparency of Pr-doped ceramics for self-calibrated temperature feedback windows

Abstract

Pr-doped metal oxide polycrystalline transparent ceramics are highly desirable for photothermal window systems served in extreme environments, however, obtaining efficient photoluminescence together with high transparency in these ceramics is still posing serious challenges, which undoubtedly limits their applications. Here, Pr-doped Y₂Zr₂O₇ (YZO) transparent ceramics, as an illustrative example, are prepared by a solid-state reaction and vacuum sintering method. Owing to the elimination of defect clusters [ Pr_Y⁴⁺-O^2- - Pr_Y⁴⁺] and [Pr_Y⁴⁺ - e'] without introduction of impurities and additional defects, the fabricated YZO:Pr ceramics exhibit high transparency (74 %) and efficient photoluminescence (39-fold enhanced) after air annealing plus vacuum re-annealing treatment. Moreover, upon 295/450 nm excitation, the emission bands (blue, green, red, and dark red) from YZO:Pr ceramic present different temperature-dependent properties due to the thermal quenching channel generated by the intervalence charge transfer state (IVCT) between Pr³⁺ and Zr⁴⁺ ions. Furthermore, a self-calibrated temperature feedback window with same FIR model (I₆₁₃/I₅₀₃) under different excitation light sources (295 nm and 450 nm) is designed. The developed photothermal window operated in a wide temperature range (303 - 663 K) shows relatively high sensitivities (<em>S</em>_a and <em>S</em>_r reach 0.008 K^-1 at 663 K and 0.47 % K^-1 at 363 K, respectively), high repeatability (&gt; 98 %), and low temperature uncertainty (&lt; 3 K). This work presents a paradigm for achieving enhanced photoluminescence along with elevated transparency of lanthanides doped ceramics through vacuum re-annealing treatment engineering and demonstrates their promising potential for photothermal window systems.