A series of ternary nitride solid solutions with a general formula of (Sr1-xCax)(2)Si5N8/Eu2+ (2 atom %) were synthesized by the carbothermal reduction and nitridation (CRN) method. The structure and luminescence properties were characterized for practical applications as a potential red phosphor for the phosphor-converted white light-emitting diodes (LEDs). The solid solutions were formed as the uniformly single phases with orthorhombic (Pmn2(1)) and monoclinic (Cc) symmetry at each end of (Sr1-xCax)(2)Si5N8, while in the range of 0.5 < x < 0.75, such solid solution phases coexisted. All of the obtained phosphors were well crystallized and the grains grew from 5 to 20 mu m with increasing Ca2+ content. These phosphors showed broadened excitation spectra originated from the 4f(7) -> 4f(6)5d transition of Eu2+ ions, so that the intense orange-red emission bands were observed under the excitation of 380-470 nm corresponding to the output lights of near-UV or blue LEDs. (c) 2006 The Electrochemical Society.