Synergistic luminescence of Tb³⁺ and Pr³⁺ ions in Sr₂Y(MoO₄)₄ for high-resolution optical thermometry

Phosphors of the SrY₂(MoO₄)₄ series co-doped with Pr³⁺ and Tb³⁺ ions were synthesized and investigated for optical temperature sensing applications. Their structure, morphology, and photoluminescent properties were thoroughly characterized using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), UV-vis absorption spectroscopy, and photoluminescence (PL) analysis. The intense dual-mode color-tunable emission revealed prominent transition bands corresponding to ⁵D₄ → ⁷F _<i>j</i> (<i>j</i> = 6, 5, 4, 3) for Tb³⁺ and ³P₀ → ³H₆ and ³P₀ → ³F₂ for Pr³⁺ ions under UV excitation at 450 nm. Chromaticity parameters for both doped and co-doped phosphors were also investigated, demonstrating emissions concentrated in the green and white regions. These properties highlight their potential for applications in solid-state lighting. The synthesized phosphors were further evaluated for their potential in optical temperature sensing based on the fluorescence intensity ratio (FIR) principle. The SrY₂(MoO₄)₄: 0.1 Pr³⁺/0.4 Tb³⁺ phosphors demonstrated strong red emission with a color purity of 85% and achieved a high relative sensitivity of 1.9% K^-1 for the 488 nm and 648 nm emission ratio, exceeding several reported molybdate-based thermometers, confirming their potential as multifunctional materials for efficient red component generation in solid-state lighting and precise, non-contact optical temperature sensing.