Preparation of Sm3+-Eu3+ coactivating red-emitting phosphors and improvement of their luminescent properties by charge compensation

By charge compensating, a series of red-emitting phosphors Ca0.54Sr0.16Ca0.54Sr0.31Eu0.08Sm0.02(MoO4)(0.6)(WO4)(0.4) were synthesized. Two approaches to charge compensation were used: (a) 2Ca(2+)/Sr2+-> Eu (3+)/Sm3++M (+), where M+ is a monovalent cation like Li+, Na+ or K+; (b) Ca2+/Sr2+-> Eu (3+)/Sm3++N (-), where N+ is a monovalent anion like F-, Cl-, Br-, or I-. One red LED was made by combining the phosphor and 390-405 nm emitting LED chip under 20 mA forward-bias current, the color purity, chromaticity coordinates and the luminous intensity of which were 99.5%, x=0.66, y=0.33, 5600 mcd, respectively.