Highly Sensitive Dual-Mode Optical Thermometry in Double-Perovskite Oxides via Pr³⁺/Dy³⁺ Energy Transfer

As increasing demand for noncontact temperature sensing, the development of a high-performance optical thermometer probe is more and more urgent. In this work, an efficient dual-mode optical thermometry strategy based on the Pr³⁺/Dy³⁺ energy transfer (ET) in some typical double-perovskite oxides is presented, which offers a promising way to design FIR/lifetime dual-mode optical thermometry with excellent temperature-measuring sensitivity and signal discrimination. According to this strategy, double-perovskite La₂MgTiO₆:Pr³⁺/Dy³⁺ phosphors are successfully synthesized. On the basis of diverse thermal responses between Pr³⁺ and Dy³⁺, the FIR of Pr³⁺ to Dy³⁺ (four FIR mode) in this material displays outstanding optical thermometry performance from 298 to 548 K. The maximum absolute and relative sensitivities (S_a and S_r) of mode 1 are 0.09 and 2.357% K^-1, being better than the current optical temperature measurement materials. For the fluorescence lifetime mode, the S_a-max and S_r-max values reach 2.85 × s 10^-4 and 1.814% K^-1. Furthermore, the dual-mode optical thermometry mechanism was presented and studied. It also demonstrated excellent optical thermometry performance in the other Pr³⁺/Dy³⁺ codoped double-perovskite oxides, such as LaMg_0.598Nb_0.402O₃, NaLa(MoO₄)₂, NaGd(MoO₄)₂, and NaLa(WO₄)₂, proving the universality of the presented strategy. This article presents an effective Pr³⁺/Dy³⁺ ET pathway for developing new and highly sensitive FIR/lifetime dual-mode optical temperature sensing materials.