A new optical temperature sensor based on the fluorescence intensity ratio of Mn2+ and Mn4+

In the course of preparing Mn-doped phosphors, the mix-valence state of Mn-n(+) ions may be obtained with associated interesting properties. This work prepared a new phosphor Ba3MgSb2O9:Mn (BMS:Mn) by a traditional high-temperature solid-state synthesis method. In this structure, Mn-n(+) can replace Mg2+ site as Mn2+ oxidation state or Sb5+ site as Mn4+. Moreover, the emitting bands of Mn2+ and Mn4+ at around 596 and 758 nm are simultaneously observed by using 350 nm as exciting wavelength. Interestingly, the temperature-dependent emitting intensities corresponding to Mn2+ and Mn4+ are different at temperatures from 10 to 300 K. With increasing temperature, the intensity of Mn2+ luminescence has some enhancement at 10-200 K and then decreases gradually, whereas Mn4+ luminescence goes into rapid decline. By using this character, BMS:0.01Mn can be used as an optical temperature sensor at 10-300 K based on the fluorescence intensity ratio of Mn2+ and Mn4+. The maximum relative sensitivity (S-r) at 125 K is as high as 1.51% K-1.

Automated summary

In this study, a new phosphor Ba3MgSb2O9:Mn was successfully prepared by a high-temperature solid-state synthesis method. The Mn-n(+) ions can replace different sites in the structure, exhibiting different emitting intensities at specific temperature ranges. This phosphor can be used as an optical temperature sensor based on the fluorescence intensity ratio of Mn2+ and Mn4+.