Ho,Yb:KLu(WO4)2 Nanoparticles: A Versatile Material for Multiple Thermal Sensing Purposes by Luminescent Thermometry

We studied the temperature dependence of the up-conversion emission in the green and the red regions of the electromagnetic spectrum of Ho,Yb:KLu(WO4)(2) nanocrystals after excitation at 980 nm and analyzed their possible applications as thermal sensors in luminescence thermometry in the RT to 673 K range by using different techniques. The different thermometric techniques used are the fluorescence intensity ratio technique of two thermally coupled Stark sublevels, the intensity ratio between the red and green luminescence bands generated by two electronically and thermally linked manifolds of these nanoparticles, lifetime measurements, or by observing the change of the color of the emitted light arising from the sample. In all cases, thermal sensitivities comparable to those previously reported in the literature are obtained, but offering different thermal sensing approaches using a single material, providing a way to corroborate the temperature measurements.