Luminescence properties of Ca super(2+) and Si super(4+) co-doped strontium molybdate red phosphors for white LEDs

• Published in: Journal of materials science. Materials in electronics Vol. 27; no. 9; pp. 9661 - 9667
• Main Authors: Wu, Dong-ni, Gong, Xin-yong, Cui, Rui-rui, Deng, Chao-yong
• Format: Journal Article
• Language: English
• Published: 01.09.2016
• Subjects: Crystallization; Electronics; Emission; Luminescence; Optical properties; Phosphors; Silicon; X-ray diffraction
• ISSN: 0957-4522; 1573-482X
• DOI: 10.1007/s10854-016-5026-z

Sr sub(0.85-x)Ca sub(x)MoO sub(4):Eu sub(0.15) super(3+) (0.15 less than or equal to x less than or equal to 0.45) and Sr sub(0.6)Ca sub(0.25)(Mo sub(1-y)Si sub(y))O sub(4):Eu sub(0.15) super(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 Sr sub(0.85-x)Ca sub(x) MoO sub(4):Eu sub(0.15) super(3+) and Sr sub(0.6)Ca sub(0.25)(Mo sub(1-y)Si sub(y)) O sub(4):Eu sub(0.15) super(3+) phosphors sintered at 800 degree C for 5 h are SrMoO sub(4) phase. And the samples are crystallized well with the scheelite structure. The luminescent properties of Sr sub(0.85-x)Ca sub(x) (Mo sub(1-y)Si sub(y))O sub(4):Eu sub(0.15) super(3+) with various concentration of Ca super(2+) and Si super(4+) were investigated in detail. The results indicate that Sr sub(0.85-x)Ca sub(x)MoO sub(4):Eu sub(0.15) super(3+) and Sr sub(0.6)Ca sub(0.25)(Mo sub(1-y)Si sub(y))O sub(4):Eu sub(0.15) super(3+) phosphors can be excited by 394 and 464 nm lights and their light emitting properties were improved by co-doping Si super(4+) and Ca super(2+) ions. The emission spectra exhibit the most intense emission at 611 and 615 nm, and the latter is corresponding to the super(5)D sub(0) arrow right super(7)F sub(2) transition of the Eu super(3+). Compared with Sr sub(0.85-x)Ca sub(x)MoO sub(4):Eu sub(0.15) super(3+), the emission intensity of Sr sub(0.6)Ca sub(0.25)(Mo sub(1-y)Si sub( y))O sub(4):Eu sub(0.15) super(3+) is increased obviously. It is found that appropriate Ca super(2+) and Si super(4+) 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 Sr sub(0.85-x)Ca sub(x)(Mo sub(1-y) Si sub(y))O sub(4):Eu sub(0.15) super(3+) excited by 394 nm light are analyzed. When the doping x of Ca super(2+) is 0.02 and y of Si super(4+) is 0.05, phosphors of the samples turn from pink to red. These results present that the Sr sub(0.85-x)Ca sub(x)(Mo sub(1-y)Si sub(y))O sub(4):Eu sub(0.15) super(3+) is an efficient red emitting phosphor for white LED applications.