Enhanced Luminescence Efficiency for Bi, Eu Doped Y₂O₃ Red Phosphors for White LEDs

Bi and Eu co-doped Y2O3 was used as a red phosphor with a very high efficiency synthesized by the solid state reaction and co-precipitation The emission spectrum consisted of a weak band at 581, 587, 593 and 599 nm corresponding to the 5D0 → 7F1 transition, with sharp peaks of maximum intensity occurring at about 611 nm due to the 5D0 → 7F2 transition of Eu3+. In addition, the excitation spectrum exhibited a broad band between 250 and 550 nm with peaks occurring at about 310 – 400 nm and a sharp peak at 465.5 nm. The relative emission intensity was improved by co-precipitation synthesis as compared to solid state reaction synthesis. This implies that an appropriate co-precipitation synthesis could improve the luminescent efficiency, particularly for the samples prepared with the optimized firing temperature of 1100 °C.