A Wide‐Range Dual‐Mode Fluorescence Thermometry Based on RE 3+ ‐Doped Negative Thermal Expansion Bimetallic Perovskite With Anti‐Thermal Quenching Luminescence Properties

ABSTRACT Non‐contact luminescence thermometry featuring high resolution and high sensitivity represents a crucial application of lanthanide upconversion materials. Nevertheless, primarily due to the thermal quenching (TQ) effect, traditional fluorides continue to present significant challenges in attaining real‐time, high‐sensitivity temperature sensing across a broad temperature spectrum. In this study, two thermometers are developed based on the thermal coupling energy levels (TCLs) and non‐thermal coupling energy levels (NTCLs) of CaZrF 6 :3%Yb; 2%Er. Benefiting from the luminescence thermal enhancement induced by lattice thermal contraction, these ratio‐type thermometers demonstrate the ability to operate within an extensive temperature range, spanning from relatively low to high temperatures (193 ∼ 793 K). TCLs and NTCLs display extraordinarily comparatively large relative sensitivity of 1.53 and 1.45% K −1 at room temperature. Most notably, based on NTCLs, the absolute sensitivity value consistently remains above 4.00 × 10 − 2 K −1 within the high‐temperature range (393–793 K), and attains a maximum of 5.08 × 10 − 2 K −1 at 543 K, which is significantly higher than those of the vast majority of Yb 3+ /Er 3+ ‐doped optical temperature‐measurement materials. These results offer a novel approach for the advancement of high‐sensitivity and high‐resolution sensor devices across a wide temperature range (Especially in high‐temperature).