La2Zr2O7:Pr3+ nanoparticles for luminescence thermometry based on a single parameter over a wide temperature range of 620 K

Abstract

Luminescence thermometry based on the variation of the fluorescence intensity ratio (FIR) of rare-earth materials has become fascinating owing to their applicability in chemically and electromagnetically harsh environments. Relevant to their practical applicability, a wide temperature sensing range is urgently required for luminescent thermometric materials besides possessing a high relative sensitivity. Herein, we have demonstrated that pyrochlore La 2 Zr 2 O 7 :Pr 3+ (LZOP) nanoparticles (NPs) can serve as a promising optical temperature sensing material over a wide temperature range of 620 K. Specifically, we have taken advantage of the intervalence charge transfer state (IVCT) of Pr 3+ doping ion for luminescence temperature sensing and confirmed excellent optical thermometric performance from the LZOP NPs in a temperature sensing range of 85–705 K. The thermal sensing here could be measured by exploiting one thermometric parameter, i.e. the FIR between 1 D 2 → 3 H 4 and 3 P 0 → 3 H 4 transitions of Pr 3+ , and thus we only need to use one calibration formula for the whole temperature range. A maximum relative sensitivity of> 0.4%·K −1 from 165 to 205 K and a low temperature uncertainty of 1.21 K at 185 K is obtained. Based on the proposed configurational coordinate diagrams, A high-lying IVCT state was demonstrated to be the cause for slow thermal quenching at high temperatures, which broadened the working range of our thermometric sensing materials. This work provides a useful inspiration for exploring appropriate host materials with slow thermal-quenching channels to develop optical thermometric materials over a wide temperature sensing range. • Synthesized La 2 Zr 2 O 7 :0.1%Pr 3+ (LZOP) NPs by a low temperature molten salt method. • Demonstrated an excitation band at ~256 nm from the 4f-5d and IVCT transitions. • Confirmed their wide range thermal sensing potential using a single parameter.