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

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 P-3(1)-S-1(0) transition of the Bi3+ ion and the D-5(0)-F-7(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.