Enhanced luminescence efficiency for Bi, Eu doped y₂O ₃ 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.