The　photoluminescence　behavior　in　a　multiple　cation　lattice　host　for　obtaining　desired　spectral　emission　is　an　important　scientific　question　to　develop　next-generation　high　quality　lighting　sources.　However,　how　to　manipulate　the　distribution　of　rare-earth　activators　over　various　cation　sites　is　still　a　technical　challenge.　Herein,　for　the　first　time,　trivalent　ions　Al3+　and　Ga3+　were　introduced　to　β-Ca3(PO4)2-kind　host　for　preparing　the　new　isostructural　Sr8CaAl(PO4)7　(SCAP)　and　Sr8CaGa(PO4)7　(SCGP)　hosts　and　controlling　the　incorporation　of　activators　Eu2+　in　the　M(4)　sites.　Their　structural　evolution,　morphology,　diffuse　reflection　spectrum,　electron　structure　and　luminescent　properties　were　systemically　investigated.　The　emission　of　Eu2+　ions　distributed　over　the　nine-coordinated　Sr(1,　3,　5)O9,　eight-coordinated　Sr(2)O8　and　special　coordinated　Sr(4)O6　sites　was　located　in　the　green　(507　nm),　yellow　(555　nm)　and　red　(610　nm)　regions,　respectively.　Further,　a　smaller　cation　radius　(Al3+)　allowed　higher　number　of　activators　(Eu2+)　to　be　accessed　to　the　neighboring　M(4)　lattice　site　for　obtaining　more　intense　red　emission,　which　would　enable　these　kinds　of　phosphors-converted　white　light　emitting　diodes　to　show　quite　high　color-rendering　indexes　(Ra　=　94.4).　This　neighboring-cation-size　strategy　mentioned　here　can　become　a　novel　approach　to　PL　spectral　modulation　through　controlling　the　distribution　of　Eu2+　activators　over　various　lattice　sites　for　excellent　solid　state　lighting.　©　2021　Elsevier　B.V.