Luminescence Thermometry via Multiparameter Sensing in YV_1–<i>x</i>P<i>_<i>x</i></i>O₄:Eu³⁺, Er³⁺

Luminescence thermometry is a remote temperature sensing technique that utilizes temperature-dependent luminescence properties. Lanthanide-doped materials with two thermally coupled emitting levels displaying a variation in luminescence intensity ratio (LIR) with temperature have been successfully explored to design sensitive luminescent thermometers. However, the low absorption strength of lanthanide parity-forbidden 4f^<i>n</i> → 4f^<i>n</i> transitions reduces the brightness. Also, this Boltzmann-type thermometer is only sensitive within a limited temperature range. To address these issues, we report here YV_1-<i>x</i>P<i>_<i>x</i></i>O₄:Eu³⁺, Er³⁺ as a luminescent thermometer. This material utilizes the sensitized emission of Ln³⁺ by strong and broad vanadate charge transfer absorption and has a wide and tunable optimum temperature range by controlling the thermal quenching of Eu³⁺ emission through a variation of <i>x</i>. The new temperature probe offers a single material with multiple temperature-dependent luminescence properties, viz. the LIR of ²H_11/2/⁴S_3/2 emission of Er³⁺, the LIR of the integrated Er³⁺ and Eu³⁺ emission intensities, and the Eu³⁺ emission lifetime. Both micro- and nanocrystalline temperature probes are reported to achieve relative sensitivities (<i>S</i>_r) from ∼0.5%/K to over 5%/K in a wide temperature range of 300-873 K. To demonstrate practical applicability, the luminescent thermometer was applied to in situ chip temperature detection revealing temperature accuracies better than 1 K.