Optimization and temperature-dependent photoluminescence properties of yellow-orange emitting Sr_(1.99-x-y)Ca_xM_y(Si_(1-y)Z_y)O_4: 0.01 Eu~(2+) (M = Y~(3+), K~+, Z = Al~(3+), P~(5+)) phosphors for white light-emitting diodes

摘要

The yellow-orange phosphors Sr_(1.99-x-y)Ca_xM_ySi_(1-y)Z_yO_4: 0.01Eu~(2+) (M = Y~(3+), K~+, Z = Al~(3+), P~(5+), 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. Ca~(2+) plays an important role in the red-shift of the emission band in Sr_(1.99-x)Ca_xSiO_4: 0.01Eu~(2+). When the Ca~(2+) 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 Sr_(1.99-x)Ca_xSiO_4: 0.01 Eu~(2+) could serve as a red phosphor for the blue LEDs. The trace doping of Al~(3+) and P~(5+) with Y~(3+) and K~+ as charge compensation significantly enhances the emission intensities of Sr_(1.29)Ca_(0.7)SiO_4: 0.01 Eu~(2+). In addition, thermal properties of typical samples are also carefully investigated.