The phase composition of Re³⁺ (Re=Lu, Gd, La) co-doped YAG:Ce and its luminescent properties

A series of Re₃₊ (Re=Lu, Gd, La) co-doped YAG phosphors were successfully synthesized by a sol-gel combustion method and characterized with XRD and photoluminescent spectrum. The phase composition and luminescent properties of YAG:Ce under different Re co-doped concentrations were investigated. Doping only 50 mol% of La³⁺ to replace Y³⁺ sites, the main phase of sample has transformed into LaAlO₃. While the concentration of Gd³⁺ reached 90-99 mol%, it was still cubic YAG. Lu³⁺ could replace Y³⁺ ions completely with the garnet structure. The location of the emission peak of Gd-codoped YAG:Ce³⁺ shifted to red region 21 nm corresponding to the maximum emission intensity before the appearance of GdAlO₃. In addition, it had a 24 nm blue shift when Y³⁺ replaced by Lu³⁺ completely.