White light LED based on YAG:Ce3+ and YAG:Ce3+,Gd3+ phosphor

YAG:Ce(3+) and a yellow-orange phosphor YAG:Ce(3+),Gd(3+) were prepared by solid-state reaction. Excitation spectrum of YAG:Ce(3+) was composed of two bands peaking at 335nm and 460nm. Emission band of YAG:Ce(3+) peaking at 532nm corresponds to the 5d -> 4f transition of Ce(3+). The emission peak wavelength of YAG:Ce(3+),Gd(3+) shifted to longer wavelength with the increasing of the concentration of Gd(3+). White LED was obtained by combining GaN(460nm) chip with different ratios of phosphor YAG:Ce(3+) and YAG:Ce(3+),Gd(3+). As the ratio of YAG:Ce(3+),Gd(3+) phosphor increased, the color rendering index of the LED improved significantly under the forward bias of 20mA. White LED with color rendering index of 85, CIE chromaticity coordinates of (0.3040, 0.2911), and color temperature Tc of 7615K was obtained as the ratio of YAG:Ce(3+) and YAG:Ce(3+),Gd(3+) was 5:3.