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 °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.