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

Abstract

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.