Energy transfer-facilitated chromaticity-tunable photoluminescence in Er³⁺ and Eu³⁺ co-doped Ca₂MgWO₆ phosphors for lighting and sensing applications

This study comprehensively evaluates the optical, and thermal characteristics of novel Ca₂MgWO₆: 2 %Er³⁺, xEu³⁺ (x = 0, 4, 8, 12, 16, and 20 mol%) phosphors synthesized via the flux-assisted solid-state reaction. First, we confirm the successful formation of the desired phase using X-ray diffraction analysis. Among the prepared phosphors, the optimum concentration of Eu³⁺ was determined to be 16 mol% before the concentration quenching, primarily arising from the dipole-quadrupole interactions. Upon 381 nm excitation, efficient energy transfer from Er³⁺ to Eu³⁺ was observed and this resulted in spectral tunability. The phosphor exhibited a direct optical band gap of 3.35 eV and temperature-dependent photoluminescence analysis revealed substantial emission retention at elevated temperatures, with a quenching temperature of 399.38 K. The optimized phosphor demonstrated excellent temperature-sensing capabilities, exhibiting peak relative sensitivities of 0.975 % K⁻¹ and 0.764 % K⁻¹ for linear and quadratic fitting models, respectively. These properties position the material as a noteworthy candidate for next-generation optical thermometry and solid-state lighting applications.