Simultaneous Enhancement and Modulation of Upconversion by Thermal Stimulation in Sc2Mo3O12 Crystals

Abstract

Rational control of photoluminescence against temperature change is important for fundamental research and technological applications. Herein, we report anomalous temperature-dependence of upconversion luminescence in Yb/Ho co-doped Sc2Mo3O12 crystals. By leveraging negative thermal expansion of the crystal lattice, energy transfer between the lanthanide do-pants is promoted with increasing temperature from 303 to 573 K, resulting in enhancement of the emission by around 5 folds. Meanwhile, the emission profile is also substantially altered due to the concurrent thermal quenching of selective energy states, corresponding to a clear color shift from green to red. By correlating the red-to-green emission intensity ratio of Ho3+ dopant ions with temperature, a ratiometric luminescence thermometer is constructed with a maximum sensitivity of 2.75% K-1 at 543 K. As the Sc2Mo3O12 crystals are thermally stable and nonhygroscopic, our findings highlight a general approach for highly reversible control of upconversion by temperature in the ambient air.