Photoluminescence and charge compensation effects in Lu3MgyAl5−x−ySixO12:Ce3+ phosphors for white LEDs

Phosphors with the nominal composition Lu2.94Ce0.06MgyAl5−x−ySixO12 (x = 0-2, y = 0-2) were synthesized by a conventional solid-state reaction in a reducing atmosphere (CO). The luminescence properties of these phosphors and the effect of charge compensation are discussed in detail. Our results indicate that the substitution of Mg2+ for Al3+ ions at octahedral coordination sites and the substitution of Si4+ for Al3+ ions at tetrahedral coordination sites are co-dependent processes because of charge compensation. Only when co-doping with Mg2+ and Si4+ ions, the incorporation of Mg2+ ions into octahedral coordination sites can be achieved. On incorporation of Mg2+ ions into the phosphor, an obvious red shift in the luminescence was observed. In addition, we analyzed the dependence of luminescence intensity on the absorptivity and the thermal quenching of the Ce3+ ions. The luminescence performances of white LEDs, fabricated by combining a single orange Lu2.94Ce0.06Mg2AlSi2O12 phosphor with blue LED chips, were determined, which demonstrate the potential of this orange phosphor for use in warm white LEDs.