Luminescence Thermometry of Pr3+-Doped Sr3Y2Ge3O12 and Sr3Sc2Ge3O12 Submicron Garnets Spanning the 13–1025 K Range and New Insight to Their Spectroscopy

Luminescence thermometry is a highly promising technique for remotely measuring temperature. Nowadays, this method is unrivaled, considering its methodology and high potential for application. However, expanding the operating range of luminescent thermometers is still a challenge. We have successfully demonstrated that by introducing just one dopant, Pr³⁺, to garnet hosts, we can create a luminescence thermometer that operates in an impressive range of 13–1025 K. Our paper also presents a thorough analysis of the Pr³⁺ location in Sr₃Y₂Ge₃O₁₂ and Sr₃Sc₂Ge₃O₁₂ garnet hosts, revealing three Pr sites in the former and two in the latter, which has not been previously reported in these phosphors. By using 5d → 4f luminescence below room temperature, we obtained relative thermal sensitivities reaching ∼6%/K. By using the luminescence intensity ratio of the 4f → 4f transitions, we achieved an operating range of 13–1025 K with relative thermal sensitivity ranging from 0.1 to 0.8%/K. Finally, the small and uniform size of the particles, about 150 nm in diameter, is attractive for high spatial resolution applications.