Dual-emission center ratiometric optical thermometer based on Bi³⁺ and Mn⁴⁺ co-doped SrGd₂Al₂O₇ 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, SrGd2Al2O7:Bi3+,Mn4+, 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 Bi3+ and Mn4+, and the energy transfer between Bi3+ and Mn4+ give it excellent signal resolution and accurate temperature detection. The S-a of SrGd2Al2O7:0.04Bi(3+),0.003Mn(4+) phosphor reaches a maximum value of 8.573% K-1 at 473 K, and the corresponding S-r is 1.927% K-1, both of which are significantly better than those of most other reported optical temperature sensing materials. Taking all the results into account, the SrGd2Al2O7:0.04Bi(3+),0.003Mn(4+) phosphor can be regarded as a prominent FIR-type temperature sensing material.