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 similar to 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.