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• Designed dual-activators in double perovskite according to site-beneficial occupation principle. • Perovskite La 3 Li 3 W 2 O 12 matrix contains abundant sites that suitable the doping of Mn4+ and Lanthanide. • Taking advantage of diverse thermal quenching between Mn4+ and Eu3+ ions for optical thermometry. Currently, Eu3+ or Mn4+ activated red-emitting fluorescent materials are widely used for solid-state lighting and optical temperature sensing. Here, we have chosen an abundant double perovskite structure that provides not only a trivalent Eu3+ lattice but also a tetravalent Mn4+ lattice and guarantees simultaneous emission. A family of rare earth (Eu3+) and transition metal (Mn4+) co-doped La 3 Li 3 W 2 O 12 (LLWO) red-emitting phosphors were obtained by designing a site-occupation strategy. By changing the concentration of Eu3+, the coordination environment of the activator is adjusted to finally achieve the adjustable emission of the phosphor from orange to red. In addition, when the doping concentration of Eu3+ is greater than 0.05, the symmetry of the doping sites in the perovskite structure decreases leading to the luminescence performance of red color and the enhancement of luminescence intensity. Finally, optical thermometry based on fluorescence intensity ratio shows that the developed phosphor has high sensitivity. [Display omitted] [ABSTRACT FROM AUTHOR]