Ratiometric optical thermometer with high-sensitive temperature sensing based on tunable luminescence of Ce3+-Eu2+ in KSr4B3O9 phosphors

Abstract

It is a challenge to develop a new type of non-contact temperature sensor and the related materials with the advantages of high detection sensitivity, spatial resolution, non-invasive and fast response. In this work, a moderate solid-state method was utilized to prepare a novel Ce3+/Eu2+ co-doped KSr4B3O9 phosphor for efficient dual-emission temperature-sensing application. According to the different activation energy and the energy transfer process from Ce3+ to Eu2+, two non-overlapping emission bands with respectively distinctive temperature responses were realized. By using the significant difference in the fluorescence intensity ratio between Eu2+ and Ce3+, a strong shift of the CIE coordinate from (0.3701, 0.4311) at 293 K to (0.2623, 0.2465) at 443 K could be read out. Meanwhile, the maximum absolute (Sa) and relative sensitivities (Sr) were fitted to be 0.0118 and 2.25 % K−1 with a large chromaticity shift from 293 to 443 K (ΔE = 0.1652). The configuration coordinate diagram in KSr4B3O9 was adopted to explain the temperature quenching mechanism in detail. The outstanding temperature-sensing characteristic indicates that KSr4B3O9: 1.75 %Ce3+/1.75 %Eu2+ phosphor has the potential to be applied in a thermometric probe.