Effect of Al/Ga Substitution on Photoluminescence and Phosphorescence Properties of Garnet-Type Y3Sc2Ga3–xAlxO12:Ce3+ Phosphor

Garnet-type Y2.96Sc2Ga3–xAlxO12:0.04Ce3+ (x = 0–3) phosphors have been prepared by using the high temperature solid-state reaction. Al/Ga ratio dependent Y3Sc2(Ga,Al)3O12 phase structures, photoluminescence (PL) properties, and long-lasting phosphorescence (LLP) properties for the Ce3+-doped phosphors have been investigated in detail. The PL emission bands of Y2.96Sc2Ga3–xAlxO12:0.04Ce3+ showed a red-shift tendency gradually from 503 to 520 nm with increasing Al content (x value), and the emission intensities increased first, maximized at x = 1, and then decreased. Y3Sc2Ga3O12:Ce3+ can show the green LLP emission, and afterglow can be obviously enhanced when (1) Al ions replaced Ga ions for a small amount and (2) the reaction atmosphere was varied from reducing to oxidation one. The afterglow emission, decay curves, and thermoluminescence (TL) of Y2.96Sc2Ga3–xAlxO12:0.04Ce3+ (x = 0–0.7) phosphors have been investigated, and related luminescence mechanisms are systematically discussed as well.