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+: 3P0 → 3H4 and 1D2 → 3H4 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 1D2 state as a detecting signal in the range of 433–593 K, the corresponding sensitivities are 0.096 μs 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.