Luminescence properties of Ca^sup 2+^ and Si^sup 4+^ co-doped strontium molybdate red phosphors for white LEDs

• Published in: Journal of materials science. Materials in electronics Vol. 27; no. 9; p. 9661
• Main Authors: Wu, Dong-ni, Gong, Xin-yong, Cui, Rui-rui, Deng, Chao-yong
• Format: Journal Article
• Language: English
• Published: New York Springer Nature B.V 01.09.2016
• DOI: 10.1007/s10854-016-5026-z
• ISSN: 0957-4522

Sr0.85-x Ca x MoO4:Eu 0.15 3+ (0.15 [less than or equal to] x [less than or equal to] 0.45) and Sr0.6Ca0.25(Mo1-y Si y )O4:Eu 0.15 3+ (0 [less than or equal to] y [less than or equal to] 0.08) red phosphors materials for white LEDs were synthesized by the high temperature solid state reaction. The properties were characterized by means of X-ray diffraction (XRD) and photoluminescence spectra. The XRD pattern shows that the Sr0.85-x Ca x MoO4:Eu 0.15 3+ and Sr0.6Ca0.25(Mo1-y Si y )O4:Eu 0.15 3+ phosphors sintered at 800 °C for 5 h are SrMoO4 phase. And the samples are crystallized well with the scheelite structure. The luminescent properties of Sr0.85-x Ca x (Mo1-y Si y )O4:Eu 0.15 3+ with various concentration of Ca2+ and Si4+ were investigated in detail. The results indicate that Sr0.85-x Ca x MoO4:Eu 0.15 3+ and Sr0.6Ca0.25(Mo1-y Si y )O4:Eu 0.15 3+ phosphors can be excited by 394 and 464 nm lights and their light emitting properties were improved by co-doping Si4+ and Ca2+ ions. The emission spectra exhibit the most intense emission at 611 and 615 nm, and the latter is corresponding to the 5D0 [arrow right] 7F2 transition of the Eu3+. Compared with Sr0.85-x Ca x MoO4:Eu 0.15 3+ , the emission intensity of Sr0.6Ca0.25(Mo1-y Si y )O4:Eu 0.15 3+ is increased obviously. It is found that appropriate Ca2+ and Si4+ concentration can enhance the luminescent intensity and improve crystallization, and the highest emission intensity on the 615 nm is exhibited when x = 0.25 and y = 0.05. Moreover, the CIE chromaticity (x, y) of Sr0.85-x Ca x (Mo1-y Si y )O4:Eu 0.15 3+ excited by 394 nm light are analyzed. When the doping x of Ca2+ is 0.02 and y of Si4+ is 0.05, phosphors of the samples turn from pink to red. These results present that the Sr0.85-x Ca x (Mo1-y Si y )O4:Eu 0.15 3+ is an efficient red emitting phosphor for white LED applications.