Abstract: Novel aluminate-based green phosphors are disclosed having the formula M1?xEuxMg1?yMnyAlzO[(x+y)+3z/2]; where 0.1<x<1.0; 0.1<y<1.0; 0.2<x+y<2.0; and 2?z?14; wherein M is selected from the group consisting of Ba, Sr, Ca, and Zn; and wherein the phosphor is configured to absorb UV and visible radiation having a wavelength ranging from about 220 to 440 nm, and emit visible green light having a wavelength ranging from about 500 to 550 nm. A novel feature of the present aluminate-based green phosphors is the relatively narrow range of wavelength over which they can be configured to emit; in one embodiment, this range is from about 518 nm to 520 nm. In an alternative embodiment, the phosphor emits visible light with a peak wavelength having a full width at half maximum of less than or equal to about 40 nm in some embodiments, and 80 nm in other embodiments.