Temperature-dependent photoluminescence studies on Y2.93-xLnxAl5O12:Ce0.07 (Ln = Gd, La) phosphors for white LEDs application

Gd3+-doped, La3+-doped and Gd3+/La3+ co-doped Y3Al5O12:Ce3+ (YAG:Ce3+) phosphors were prepared by high-temperature solid-state reaction. Their crystal structure and photoluminescence properties at various temperatures (25-200 degrees C) were investigated. By increasing the substitution concentration of Gd3+ in YAG:Ce3+ phosphor, the Ce3+ emission band shifts toward longer wavelength but shows a stronger thermal quenching. Addition with small amount of La3+ can improve the thermal stability of YAG:Ce3+ phosphors without leading to evident shifts of Ce3+ emission band. The La3+ and Gd3+ doping can complement each other. The Gd3+/La3+ co-doped YAG:Ce3+ phosphors have longer wavelength emission and furthermore exhibit good thermal stability, which is especially favorable for high power white LEDs aiming at general illumination. (C) 2010 Elsevier B.V. All rights reserved.