Luminescence properties of YAG:Ce, Gd phosphors synthesized under vacuum condition and their white LED performances

Abstract

Modified YAG:Ce, Gd phosphors were synthesized by vacuum solid-state reaction. With the increase of Gd3+ concentration, the emission spectra of YAG:Ce, Gd phosphors shifted greatly to longer wavelength. At 400 K, YAG:Ce, Gd phosphors with 20 at.% Gd3+ could maintain 78% of room temperature intensity. Within the maximum junction temperature of a high brightness LED (around 400 K), the color coordinates of phosphors changed very little. In addition, white LEDs with a color rendering index of 82, luminous efficiency of 109 lm/W and color temperature of 5656 K were achieved by using optimized YAG:Ce, Gd phosphors.