Colour Tunable Ca2MgWO6:Dy3+, Eu3+ Phosphors for FIR-Based Temperature Sensing: Energy Transfer Dynamics and Higher-Order Polynomial Modelling

The development of thermally stable and colour tunable phosphors is critical for advanced solid-state lighting and optical temperature-sensing applications. In this work, a series of Ca 2 MgWO 6 phosphors doped with 3 mol% Dy 3+ and varying concentrations of Eu 3+ (x = 0, 2, 5, 8, 11, 14 mol%) were synthesized via a solid-state reaction method. The study demonstrates efficient energy transfer from Dy 3+ to Eu 3+ ions, enabling colour tunability, with an optimal Eu 3+ concentration of 5 mol% before concentration quenching occurs. The optimized phosphor exhibits a direct band gap of 3.34 eV and excellent thermal stability, retaining significant luminescence up to 498 K, with a thermal quenching temperature of 389.71 K and activation energy of 0.27 eV. Temperature-dependent photoluminescence analysis using higher-order polynomial fits revealed maximum absolute and relative sensitivities of 0.0778 K − 1 at 423 K and 0.96% K − 1 at 498 K, respectively. These findings signify that the prepared Ca 2 MgWO 6 :Dy 3+ , Eu 3+ phosphors demonstrates great potential for applications in optical thermometry and lighting technologies.