White light-emitting diodes using blue and yellow orange-emitting phosphors

A blue-emitting phosphor, BaMgAl10O17:Eu2+ (BAM) and a yellow orange phosphor, Ba2+-codoped Sr3SiO5:Eu2+ were prepared by the solid-state reaction. Excitation and emission spectra results showed that BAM and Ba2+-codoped Sr3SiO5:Eu2+ can be efficiently excited by near-ultraviolet (n-UV)-visible light from 250 to 440 nm. The effects of the doped-Eu2+ concentration in BAM and Ba2+-codoped Sr3SiO5:Eu2+ on the photoluminescence were investigated in detail. White light-emitting diodes (LED) was obtained by combining n-UV LED chip (GaN-based 380 nm emitting) with BaMgAl10O17:0.09Eu(2+) and 0.1Ba(2+)-codoped Sr3SiO5: 0.2Eu(2+) phosphors with the characteristic of color-rendering index of 86, CIE chromaticity coordinates (x,y) of (0.3216,0.3096), and color temperature T-c of 5700 K. As the current increases, the relative intensity simultaneously increases. The CIE chromaticity coordinates (x,y) of the white LED tends to decrease. The correlated color temperature T-c increases from 4100 to 7500 K and the color-rendering index R-a increases from 82 to 87 simultaneously. (c) 2009 Elsevier GmbH. All rights reserved.