Synthesis and photoluminescence properties of color-tunable BaLa2WO7:Eu3+ phosphor

Color-tunable phosphors BaLa2-xEuxWO7 were synthesized via a solid-state reaction. The absorption, excitation, emission and decay curves were obtained to study the luminescence properties. The experimental results indicate that BaLa2-xEuxWO7 phosphors have two regions in the excitation spectra: one is assigned to the charge-transfer state (CTS) band at about 338 nm, and the other is assigned to the intra-4f transitions at 360-600 nm. The emission spectra of BaLa2-xEuxWO7 phosphors excited at 395 nm exhibit a series of sharp peaks, which are attributed to the D-5(0)-> F-7(J) (J = 0, 1, 2, 3, 4) transitions. Luminescence from higher excited states, such as D-5(1), D-5(2), and D-5(3), were also observed at low Eu3+ concentration. The optimal emission intensity of D-5(0)-> F-7(2) red emission is at x=0.4 (BaLa1.6Eu0.4WO7). The chromaticity coordinates of BaLa2-xEuxWO7 phosphors vary with Eu3+ content from white, orange-red, to red, making it a candidate for a white-light-emitting phosphor in UV-LEDs. (C) 2011 Elsevier B. V. All rights reserved.