Optical Thermometry by Monitoring Dual Emissions from YVO₄ and Eu³⁺ in YVO₄:Eu³⁺ Nanoparticles

Contactless optical thermometry is successfully applied for accurate local temperature sensing in many scientific and technological areas. The majority of optical thermometers utilize a ratiometric approach between thermally coupled levels. Such sensors have an inherent limitation of relative thermal sensitivity linked to the maximal energy gap between these levels, which can make them useless for some important applications. Here, we report simple dual-center YVO4:Eu3+ thermometers that do not have this limitation. Thermal sensing using YVO4:Eu3+ nanoparticles is based on monitoring the luminescence intensity ratio between YVO4 host emission and Eu3+ luminescence lines. By taking advantage of the different temperature behavior of the aforementioned emission bands, contactless sensing was demonstrated within the 123–423 K range. High thermometric performances including subdegree temperature resolution (up to 0.2 K) and relative thermal sensitivity (up to 1.4% K–1) at room temperature reveal the good potential of YVO4:Eu3+ phosphors for thermometry and lay a foundation for the future development of dual-center probes.