Broadening the valid temperature range of optical thermometry through dual-mode design

In this study, a double-perovskite Pr3+:Gd2ZnTiO6 thermometric phosphor is designed and successfully synthesized for the first time via a high-temperature solid-state method. By taking advantage of the intervalence charge transfer state (IVCT) interfered Pr3+ luminescence, the synthesized phosphor exhibits excellent optical thermometric performance in terms of both the fluorescence intensity ratio and luminescence lifetime. Specifically, by using the fluorescence intensity ratio between Pr3+: P-3(0) -> H-3(4) and D-1(2) -> H-3(4) transitions as a temperature detecting signal in the range of 293-433 K, the maximum absolute and relative sensitivities reach as high as 0.63 K-1 and 1.67% K-1, respectively; taking the fluorescence lifetime of the D-1(2) state as a detecting signal in the range of 433-593 K, the corresponding sensitivities are 0.096 mu s K-1 and 1.48% K-1. The results demonstrate that a thermal reading with high sensitivity over a wide range of temperature can be realized by this novel dual-mode design.