Multimodal Synergistic Thermometry: Designing Wide-Range Optical Thermometers via Eu 3+ /Er 3+ Co-Doped YVO4

In this paper, a five-mode synergistic thermometry system based on Eu3+/Er3+ co-doped YVO4 fluorescent material was developed. By utilizing the spectral properties of the phosphor, two luminescence intensity ratio (LIR) and two excitation intensity ratio (EIR) thermometry modes were established, and the fluorescence lifetime thermometry (τ) mode of Eu3+ ⁵D₀→⁷F₂ was also introduced into this system. The Sr values of both Er3+ and Eu3+/Er3+ based LIR modes decrease with increasing temperature, and the Srmax of LIR modes is 0.98% K-1. Similarly, the EIR mode via V–O charge transfer (monitoring Er³⁺ emissions) shows a declining Sr trend, achieving Srmax = 1.01% K⁻¹ at 300 K. Unlike conventional LIR systems, the EIR mode based on Eu3+ (7F0→5D4/7F0→5L6) exhibites a distinct different temperature dependence in its Sr value, with a Srmax is 0.65% K-1 at 500 K. The Srmax of τ mode can reach 0.71% K-1 at 500 K which is superior to other systems. Notably, the EIR and τ modes address the limited high-temperature sensitivity of Boltzmann-type thermometry. In short, the YVO₄: Eu³⁺, Er³⁺ phosphor exhibits excellent thermometric performance and application potential