Anti-thermal quenching upconversion luminescence of Cr³⁺ in Sc₂(WO₄)₃:Yb/Cr

Although widely need from various applications, the luminescence of Cr³⁺ is easily prone to thermal quenching (TQ), causing remarkable intensity reduction as temperature rises, and posing a significant constraint in applications such as high-power lighting, solid-state lasers, and high-temperature optical sensing. Numerous strategies have been reported to realize anti-thermal quenching luminescence (ATQL) of Cr³⁺. However, researches into anti-thermal quenching upconversion luminescence (ATQUL) of Cr³⁺ are barely seen. Herein, taking advantage of the enhanced luminescence of Yb³⁺ facilitated by the Frenkel defects formed within Sc₂(WO₄)₃ (SWO) matrix upon heating, we have established Yb³⁺ $\to$ Cr³⁺ cooperative sensitization pathway for upconversion luminescence of Cr³⁺, and achieved ATQUL of Cr³⁺ in SWO:Yb/Cr. Our findings have not only offered novel perspectives for medium to high-temperature applications of Cr³⁺-based phosphors, the design principles are also extendable to other transition metal ions.