Ratiometric thermometry using single Er 3+ -doped CaWO 4 phosphors.

Single doped CaWO 4 :Er 3+ phosphors were synthesized and studied for application of optical thermal sensing within a wide range of 98-773 K. Ratiometric strategy utilizing two luminescence intensity ratios, one between host and Er 3+ band (LIR 1 ) and second between different Er 3+ transitions (LIR 2 ), results in self-referencing temperature readouts. The presence of two temperature-dependent parameters could improve thermometric characteristics and broaden the working temperature range compared to a usual single-parameter thermometer. Thermometric performances of prepared samples were evaluated in terms of thermal sensitivities, temperature resolution and repeatability. The highest sensitivity of 2.09% K -1 @300 K was found for LIR 1 , whereas LIR 2 provided more accurate thermal sensing with a temperature resolution of 0.06-0.1 K. Effect of Er 3+ doping concentration on sensing properties were studied. The presented findings indicate that CaWO 4 :Er 3+ phosphors are perspective in dual-mode thermal sensing with high sensitivity and sub-degree resolution.