Ratiometric thermal sensing based on Eu³⁺-doped YVO₄ nanoparticles

This work is devoted to the study of Eu³⁺-doped yttrium vanadate colloidal nanoparticles as possible thermal sensors. YVO₄:Eu³⁺ 6 at.% nanoparticles were synthesized by modified Pechini technique. The structural properties were studied with XRD, SEM, and SLS. XRD pattern indicates that nanocrystalline YVO₄:Eu³⁺ powders form only pure tetragonal phase without any impurities. SEM and SLS measurements reveal that average size of synthesized nanoparticles is 60 nm. Photoluminescence measurements show characteristic 4f–4f transitions of Eu³⁺ ions upon 300 nm excitation. Relative intensities of Stark sublevels of ⁵D₀–⁷F₂ transitions demonstrate temperature dependence which enables ratiometric luminescence thermal sensing. The thermal sensitivity has been successfully calculated and compared to the previously reported nanothermometers.