Achieving three-mode optical thermometry via Sr3La(VO4)3:Eu3+ phosphors

Multi-mode optical thermometry is recently regarded as a promising technique for accurate temperature measurement. In this work, a series of Sr₃La_1−x(VO₄)₃:xEu³⁺ (x = 0–0.10) samples was successfully prepared. Owing to the energy transfer between VO₄³⁻ groups and Eu³⁺ ions, Sr₃La_1−x(VO₄)₃:xEu³⁺ phosphors emit emissions from VO₄³⁻ and Eu³⁺ synchronously upon excitation with 350 nm light. And the luminescent intensities of VO₄³⁻ and Eu³⁺ have different decreasing tendencies as temperature increases. Therefore, fluorescence intensity, fluorescence intensity ratio, and coordinates of Commission Internationale de L'Eclairage modes of Sr₃La_1−x(VO₄)₃:xEu³⁺ thermometry were designed. Notably, their maximum relative sensitivities (S_R) reach as high as 2.93 %K⁻¹ @ 320 K, 2.65 %K⁻¹ @ 303 K, and 0.37 %K⁻¹ @ 357 K, respectively. Moreover, S_R values of fluorescence intensity and fluorescence intensity ratio modes maintain higher than 1.55 %K⁻¹ and 1.25 %K⁻¹ at temperature range of 303–483 K. Our findings show that Sr₃La_1−x(VO₄)₃:xEu³⁺ phosphors have promising applications for accurate temperature measurement.