Optimization and temperature-dependent photoluminescence properties of yellow-orange emitting Sr1.99-x-yCaxMy(Si1-yZy)O4: 0.01Eu2+ (M = Y3+, K+, Z = Al3+, P5+) phosphors for white light-emitting diodes

The yellow-orange phosphors Sr(1.99-x-y)Ca(x)M(y)Si(1-y)Z(y)O(4): 0.01Eu(2+) (M = Y3+, K+, Z = Al3+, P5+, 0 <= x <= 0.9, 0 <= y <= 0.01) were synthesized by the solid state reaction. X-ray diffraction and photoluminescence spectra were utilized to characterize the samples. The results indicate that the phosphors can be efficiently excited by the UV-blue light and show a broad band emission from about 425 to 700 nm. Ca2+ plays an important role in the red-shift of the emission band in Sr1.99-xCaxSiO4: 0.01Eu(2+). When the Ca2+ concentration x = 0.7, the emission peak under the excitation of 450 nm reaches a maximum at about 600 nm, which implies that the samples Sr1.99-xCaxSiO4: 0.01Eu(2+) could serve as a red phosphor for the blue LEDs. The trace doping of Al3+ and P5+ with Y3+ and K+ as charge compensation significantly enhances the emission intensities of Sr1.29Ca0.7SiO4: 0.01Eu(2+). In addition, thermal properties of typical samples are also carefully investigated. (C) 2014 Elsevier B.V. All rights reserved.