A multi-mode self-calibrating visual optical thermometer based on Eu3+-doped Y2WO6

Abstract

With the continuous advancement of sensor technology, multi-mode high-precision optical thermometers have become a key research focus in the field of temperature sensing. Nevertheless, studies on visualizable multi-mode optical thermometry (MMOT) are still considerably lacking. Herein, a series of novel Y₂WO₆:Eu³⁺ phosphors were prepared. The down-conversion luminescence spectra of the materials were systematically investigated. Upon excitation by a 315 nm laser, the [WO₆]^6- group exhibits an emission at 455 nm, while Eu³⁺ ions show characteristic emissions at 590, 610, 627, 654 and 705 nm. Due to the distinct temperature responses of these emission spectra of the two luminescent centers, four-mode optical thermometry was successfully achieved based on the fluorescence intensity ratio (FIR) between 455 nm and 610 nm, Commission Internationale de L'Eclairage (CIE) coordinates, the single-peak fluorescence intensity ratio (SFIR) at 455 nm, and the excitation intensity ratio (EIR) at 610 nm. The maximum relative sensitivity (S_r) values can reach 4.08% K⁻¹ at 303 K, 0.77% K⁻¹ at 337 K, 1.95% K⁻¹ at 363 K, and 4.29% K⁻¹ at 303 K, respectively. Additionally, visual fluorescence thermometry with distinct color transitions from purple to deep red is realized in this work over the temperature range of 303 K to 483 K. These temperature-sensing properties demonstrate that Y₂WO₆:Eu³⁺ phosphors exhibit promising application potential in visual multi-mode self-calibrating optical thermometry.