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 F-4(9/2) (Er3+) and F-3(2) (Tm3+) states and thus the occurrence of multiphonon assisted energy transfer process (Er3+-> Tm3+), two upconversion (UC) emission bands corresponding to F-4(9/2) -> I-4(15/2)(Er3+) transition and F-3(2) -> H-3(6) (Tm3+) one exhibit distinct temperature-dependent behaviors, which result in monotonous decrease of the related fluorescent intensity ratio (I-Er/I-Tm) 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.