Simple synthetic LiCa(Yb,Nd)(WO4)3:Er up-conversion phosphor for photothermal conversion and thermometry applications

Abstract

A bifunctional material LiCa(Yb,Nd)(WO₄)₃:Er with thermometry and photothermal conversion was synthesized by a simple one-step sintering method. The Nd³⁺ co-doping not only enriched the UV–vis absorption peak, but also increased the particle layout in the highly excited state ²H_11/2 of Er³⁺. A near-constant sensitivity of 0.01 K^-1 was obtained over a wide temperature range (30–480 °C) based on the fluorescence intensity ratio technique of the two thermal-coupled transitions of Er³⁺ (²H_11/2/⁴S_3/2 → ⁴I_15/2). More surprisingly, the sample exhibited excellent photothermal conversion characteristics under near-infrared excitation light. Under 980 or 808 nm excitation, the sample achieved an increase of temperature of 58 °C in 2 min, which is comparable to the core-shell nanostructures synthesized through multi-step complex procedures. Finally, a prototype device was used to demonstrate the feasibility of simultaneous heating and temperature measurement. The above results showed the potential application of the sample as both a thermometer and a photoheater.