In this work, a series of Eu 2+ -doped (Ca 1− x Sr x ) 8 MgLu(PO 4 ) 7 and Eu 2+ /Mn 2+ -codoped Ca 6.5 Sr 1.5 MgLu(PO 4 ) 7 phosphors were prepared via the combustion-assisted solid-state reaction process. XRD patterns and Rietveld refinements were used to verify the incorporations of Sr into Ca 8 MgLu(PO 4 ) 7 :Eu 2+ . Upon the same excitation wavelength of 380 nm, the emission peaks of Eu 2+ -doped (Ca 1− x Sr x ) 8 MgLu(PO 4 ) 7 (0≤ x ≤1) phosphors red-shifted from 453 to 519 nm with increasing Sr/Ca ratio. The red-shift of the Eu 2+ emission with increasing Sr/Ca ratio was ascribed to the change of Eu 2+ emission at different lattice sites. With variation of the Mn 2+ content, the emission color of Eu 2+ /Mn 2+ codoped Ca 6.5 Sr 1.5 MgLu(PO 4 ) 7 phosphors exhibited the luminescence tunable from greenish blue to white and eventually to red. The energy transfer from Eu 2+ to Mn 2+ in Ca 6.5 Sr 1.5 MgLu(PO 4 ) 7 host matrix was demonstrated to be of a resonant type via a dipole- dipole mechanism with the critical distance of ∼16.7 Å. By the Sr substitution for Ca and properly tuning by the relative composition change of Eu 2+ /Mn 2+ , chromaticity coordinates of (0.329, 0.326) can be reached at near UV light excitation. The combination of host composition design and energy transfer may provide a novel strategy to obtain white light and tunable luminescence. [ABSTRACT FROM AUTHOR]