Supersensitive Ratiometric Thermometry and Manometry Based on Dual‐Emitting Centers in Eu²⁺/Sm²⁺‐Doped Strontium Tetraborate Phosphors

Abstract The concept of optical temperature sensing using band intensity ratio is considered as one of the most effective, self‐reference, non‐invasive, and rapid detection techniques for the local temperature in natural or engineered systems. In this work, for the first time a divalent lanthanide‐co‐doped dual‐center system, i.e., SrB₄O₇:Eu²⁺/Sm²⁺ phosphors, working as a bifunctional ratiometric sensor of temperature and pressure is employed. With temperature alterations, the Eu²⁺/Sm²⁺ luminescence intensity ratio and the emission lifetime of Sm²⁺ are significantly changed, showing unprecedentedly high relative sensitivity of 45.6 and 3.17% K^‐1, respectively. Moreover, in the pressure range from ≈10 to 40 GPa, the intensity ratio of the Eu²⁺/Sm²⁺ emissions shows strong pressure dependence and can be utilized for pressure monitoring, with high pressure relative sensitivity of ≈13.8% GPa^‐1. The superior performance indicates that the developed dual‐center Eu²⁺/Sm²⁺‐co‐doped SrB₄O₇ phosphors are promising candidates for supersensitive optical sensing applications. The findings open a new approach of designing optical temperature and pressure sensors.