A novel greenish yellow-orange red Ba3Y4O9:Bi3+,Eu3+ phosphor with efficient energy transfer for UV-LEDs

Abstract

A series of novel color-tunable Ba₃Y₄O₉:Bi³⁺,Eu³⁺ phosphors were prepared for the first time via the high-temperature solid-state reaction route. The effect of Bi³⁺ concentration on the emission intensity of Ba₃Y₄O₉:Bi³⁺ was investigated. The emission spectra of the Ba₃Y₄O₉:Bi³⁺,Eu³⁺ phosphors present both a greenish yellow band of Bi³⁺ emission centered at 523 nm, and many characteristic emission lines of Eu³⁺, derived from the allowed ³P₁–¹S₀ transition of the Bi³⁺ ion and the ⁵D₀–⁷F_J transition of the Eu³⁺ ion, respectively. The energy transfer phenomenon from Bi³⁺ to Eu³⁺ ions is observed under UV excitation in Bi³⁺, Eu³⁺ co-doped Ba₃Y₄O₉ phosphors, and their transfer mechanism is demonstrated to be a resonant type via dipole–quadrupole interaction. The critical distance between Bi³⁺ and Eu³⁺ for the energy transfer effect was calculated via the concentration quenching and spectral overlap methods. Results show that color tuning from greenish yellow to orange red can be realized by adjusting the mole ratio of Bi³⁺ and Eu³⁺ concentrations based on the principle of energy transfer. Moreover, temperature-dependent PL properties, CIE chromaticity coordinates and quantum yields of Ba₃Y₄O₉:Bi³⁺,Eu³⁺ phosphors were also supplied. It is illustrated that the as-prepared Ba₃Y₄O₉:Bi³⁺,Eu³⁺ phosphors can be potential candidates for color-tunable phosphors applied in UV-pumped LEDs.