Lanthanide-doped LuF3 mesocrystals for optical thermometry

Yb3+/Er3+/Tm3+ triply doped LuF3 mesocrystals have been successfully synthesized to explore their possible application in optical temperature sensors. Especially, owing to the non-resonant energy match between the 4F9/2 (Er3+) and 3F2 (Tm3+) states and thus the occurrence of multiphonon assisted energy transfer process (Er3+→ Tm3+), two upconversion (UC) emission bands corresponding to F9/24→I15/24 (Er3+) transition and F23 → H63 (Tm3+) one exhibit distinct temperature-dependent behaviors, which result in monotonous decrease of the related fluorescent intensity ratio (IEr/ITm) with increased temperature. Consequently, the high sensitivity of 20.6% per K for LuF3:Yb3+/Er3+/Tm3+ mesocrystals may make them very promising candidate as optical temperature sensor.