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

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 approximate to 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 approximate to 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.

Automated summary

The concept of optical temperature sensing using band intensity ratio is a highly effective and non-invasive technique. In this study, a dual-center system, SrB4O7:Eu2+/Sm2+ phosphors, was employed as a bifunctional sensor for temperature and pressure. The phosphors showed high sensitivity and pressure dependence, making them promising candidates for optical sensing applications.