Synthesis of green-emitting phosphors based on lanthanum oxysulfate by a flux method

Green-emitting phosphors based on lanthanum oxysulfate, La2O2SO4 : x at.%.Tb3+ (5 <= x <= 15), were synthesized in a single phase form by our original flux method using a 0.6Li(2)SO(4)-0.4Na(2)SO(4) eutectic mixture, and the photoluminescence properties were characterized. The flux treatment brought an increase in the crystallinity of the oxysulfate phosphor, and surface defects of the phosphor can be eliminated effectively, leading to the enhancement of emission intensity. The excitation spectrum consisted of a strong broad peak from 220 to 260 nm, corresponding to the 4f-5d transition of Tb3+. The oxysulfate phosphors exhibit typical emission peaks assigned to the transition from D-5(4) to F-7(J) (J = 6, 5, 4, 3) of Tb3+, and the maximum peak intensity was obtained for La2O2SO4 : 10 at.%Tb3+.