The new dual-emitting and color tunable single phase of Na2BaSr(PO4)(2):0.03Eu(2+), xMn(2+) (NBSP:0.03Eu(2+), xMn(2+)) phosphor are successful prepared in this work. The phase purity and photoluminescence properties are investigated. Regarding to the coordination, valence and cation radius, the Eu2+ ions occupy the Sr2 and Sr3 site and Mn2+ ions occupy the Sr3 site. According to the photoluminescence (PL) spectra of NBSP:0.03Eu(2+), xMn(2+) (x = 0-0.09), the strong energy transfer (ET) between Eu2+ and Mn2+ exists in these phosphors. The strong ET efficiency from Eu2+ to Mn2+ is as high as 92%...
