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 5D0 → 7FJ (J = 0, 1, 2, 3, 4) transitions. Luminescence from higher excited states, such as 5D1, 5D2, and 5D3, were also observed at low Eu3+ concentration. The optimal emission intensity of 5D0 → 7F2 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.

► BaLa2−xEuxWO7 phosphor was synthesized. ► BaLa2−xEuxWO7 is a color-tunable phosphor. ► Increasing Eu3+ concentration changed the color tone of BaLa2−xEuxWO7.