Structural, optical and temperature-sensing properties of LaOF:Yb3+, Tm3+ nanophosphor prepared by microwave-assisted hydrothermal synthesis

Abstract

Luminescence thermometry forms a unique tool for remote temperature sensing by exploiting the variations in the luminescence properties of the probe. Thermometry based on the fluorescence intensity ratios (FIR) is a widely practiced approach due to them being a self-referenced measure. The quest for efficient temperature probes for thermometry led to the discovery of LaOF:Yb3+,Tm3+ upconversion nanoparticles, which were synthesized using a microwave-assisted hydrothermal synthesis method. Blue and near-infrared upconversion photoluminescence (UCPL) emission was observed under 980 nm laser excitation. The temperature-dependent UCPL was studied for their temperature sensing application. FIR of thermally coupled and non-coupled emission bands were calculated in the temperature range of 303 to 473 K. The thermometric characteristics such as absolute sensitivity, relative sensitivity and temperature uncertainty were also determined. The thermal stability of the UCNPs was established under continuous laser exposure operating at maximum power (2500mW). The reproducibility of the UCNPs was also determined by temperature cycling the UCNPs.