Luminescence and optical thermometry strategy based on emission and excitation spectra of Pr3+ doped SrMoO4 phosphors

Recent developments of luminescence ratiometric thermometry have attracted much attention owing to its merits of fast response, non-invasiveness and high spatial resolution. In this work, the synthesis, crystal structure and luminescence properties has been carried out for Pr³⁺-activated SrMoO₄ phosphors as optical thermometry. The XRD results show that all the phosphors possess the scheelite type tetragonal structure with space group I4₁/a. The efficient luminescence of Pr³⁺ can be observed under intra-configurational (4f-4f) and charge transfer band (Mo–O) excitations, respectively. Upon different excitations, the quenching concentration of Pr³⁺ is diverse due to the multi-phonon relaxation and cross-relaxation processes occurring in different excited states of Pr³⁺ ions. The fluorescence intensity ratio (FIR) techniques based on emissions of ³P₀ and ¹D₂ excited states of Pr³⁺, and the FIR in the excitations of the charge transfer band (Mo–O) and 4f-4f transitions of Pr³⁺ were employed for the thermometric characterizations in the 298–498 K range. Both results show remarkable performance in temperature sensing with the maximum relative sensitivity of 0.45%K^?1@489 K and 0.98 %K^?1@298 K, respectively. Our study demonstrates that Pr³⁺-activated SrMoO₄ phosphors have a promising potential application in non-contact optical thermometry.