An up-conversion Ba3In(PO4)3:Er3+/Yb3+ phosphor that enables multi-mode temperature measurements and wide-gamut 'temperature mapping'

At present, most fluorescent materials that can be used for optical temperature measurement exhibit poor thermochromic performance, which limits their applications. In this study, the phosphor Ba3In(PO4)(3):Er/Yb was synthesized with a high doping concentration of Yb3+, and it emitted composition- and temperature-induced wide color gamut up-conversion luminescence from red to green. Four modes of fluorescence thermometry can be realized in the temperature range of 303-603 K, which is based on the ratio of fluorescence intensity between thermally coupled energy levels and non-thermally coupled energy levels, color coordinate shift, and fluorescence decay lifetime, respectively. The highest Sr value obtained was 0.977% K-1. Taking advantage of the fact that temperature can significantly change the luminous color of the phosphor Ba3In(PO4)(3):0.02Er(3+)/0.05Yb(3+), we demonstrated 'temperature mapping' on a smooth metal surface with multiple optical encryptions. These results indicate that the Ba3In(PO4)(3):Er/Yb phosphor is an excellent fluorescent material for thermal imaging and has great application potential in temperature visualization measurement and optical encryption.

Automated summary

In this study, a phosphor Ba3In(PO4)(3):Er/Yb was synthesized with high Yb3+ doping concentration, which exhibited wide color gamut up-conversion luminescence from red to green with temperature variation. Four modes of fluorescence thermometry were realized based on the ratio of fluorescence intensity, color coordinate shift, and fluorescence decay lifetime. The highest temperature sensitivity obtained was 0.977% K-1. By using Ba3In(PO4)(3):0.02Er(3+)/0.05Yb(3+) phosphor, temperature mapping on a smooth metal surface with multiple optical encryptions was demonstrated. The Ba3In(PO4)(3):Er/Yb phosphor is an excellent fluorescent material for thermal imaging and has great potential in temperature visualization measurement and optical encryption.