YAG:Dy co-doped with Tb for lifetime-based phosphor thermometry from room temperature to 1600 °C

Phosphor thermometry has demonstrated significant potential for nondestructive high-temperature measurements in gas turbines. To expand the measurement range through lifetime-based phosphor thermometry, we developed a novel phosphor, YAG:Dy co-doped with Tb (YAG:Dy,Tb). Three YAG:Dy,Tb samples with varying Tb concentrations were synthesized through the sol–gel method. A fiber-optic-coupled measurement system was established to capture multiple emission peaks of YAG co-doped with Dy³⁺ and Tb³⁺ at 544 nm, 484 nm, and 458 nm. Efficient energy transfer from Dy³⁺ to Tb³⁺ resulted in a substantial enhancement of Tb³⁺ emission at 544 nm under 355 nm excitation. Owing to the energy transfer, the temperature measurement range under the lifetime method was extended from room temperature to 1600 °C using the combination of Tb³⁺ emission at 544 nm and Dy³⁺ emission at 458 nm. YAG:Dy,Tb samples with higher concentrations of Tb³⁺ exhibited superior temperature measurement performance, mainly owing to their stronger signal-to-noise ratio at >1000 °C. The performances of different emission peaks were also compared according to temperature uncertainty, which generally ranged from 0.1 °C to 2.7 °C across the entire measurement range.