Tuning of the up-conversion emission and sensitivity of luminescent thermometer in LiLaP4O12:Tm,Yb nanocrystals via Eu3+ dopants

Up-converting properties of LiLaP4O12:1%Tm3+, 50%Yb3+, x% Eu3+ nanocrystals were investigated upon 975 nm excitation. It was shown that their emission color can be tuned from blue to orange via changing Eu3+ concentration from 10% to 49%. The potential suitability of these nano-phosphors for non-contact temperature sensing was investigated. Thermal changes of luminescence intensity ratio of 1D2→3F4 and 1G4→3F4 emission bands of Tm3+ ions were strongly affected by Eu3+ concentration owing to increasing efficiency of distance-dependent Tm3+→Eu3+ energy transfer. The sensitivity of such luminescence thermometer was varying from 0.1%/°C to 1.9%/°C in response to varying Eu3+ concentration from 49 down to 10%.