Dual-emission center ratiometric optical thermometer based on Bi 3+ and Mn 4+ co-doped SrGd 2 Al 2 O 7 phosphor.

In recent years, more and more attention has been paid to optical temperature sensing, and how to improve its accuracy is the most important issue. Herein, a new temperature sensing material, SrGdAlO:Bi,Mn, based on fluorescence intensity ratio was designed in this work. It has both blue-purple and red luminescence under 300 nm excitation, and the dual-emitting centers with distinct colors, the different thermal sensitivities of Bi and Mn, and the energy transfer between Bi and Mn give it excellent signal resolution and accurate temperature detection. The of SrGdAlO:0.04Bi,0.003Mn phosphor reaches a maximum value of 8.573% K at 473 K, and the corresponding is 1.927% K, both of which are significantly better than those of most other reported optical temperature sensing materials. Taking all the results into account, the SrGdAlO:0.04Bi,0.003Mn phosphor can be regarded as a prominent FIR-type temperature sensing material.