Investigation of SrB₄O₇:Sm²⁺ as a Multimode Temperature Sensor with High Sensitivity

Sm²⁺-doped SrB₄O₇ was synthesized for high-sensitivity thermometry. A high thermal-sensitive fluorescence intensity ratio and fluorescence lifetime were achieved in a wide temperature range. At 500 K, the relative sensitivity of the temperature sensing was 2.16% K^-1 for the fluorescence intensity ratio and 3.36% K^-1 for the fluorescence lifetime. Furthermore, the fluorescence color-shifted dramatically from deep red at room temperature to green at 700 K. On the basis of this color change, a visible temperature field was obtained on quartz glass covered with our sample, which made the thermal conduction and distribution visible to the human eye. The temperature of the temperature field was determined using two methods. These outstanding properties, combined with the high sensitivity, multimode for temperature sensing and thermal stability of the sample, make SrB₄O₇:Sm²⁺ a promising material for highly sensitive thermometry applications.