Synthesis and photoluminescence properties of Ba1−ySryLa4−xDyx(WO4)7 (x = 0.04–0.2, y = 0–0.4) phosphors

Ba1−ySryLa4−xDyx(WO4)7 (x = 0.04–0.2, y = 0–0.4) phosphors were prepared via a solid-state reaction, and their photoluminescence properties were investigated. Under near-UV (388 nm) excitation, the emission spectra of BaLa4−xDyx(WO4)7 exhibited emission peaks in the visible region at 453, 479, and 573 nm, which are assigned to the intra-4f-shell transitions from the (4M21/2 + 4I13/2 + 4K17/2 + 4F7/2 → 6H13/2), (4F9/2 → 6H15/2), and (4F9/2 → 6H13/2) transitions, respectively. The concentration quenching effect occurs when the Dy3+ concentration is x = 0.12 (3 at.%). A partial substitution of Ba2+ by Sr2+ in Ba1−ySryLa3.88Dy0.12(WO4)7 can not only enhance the emission intensity of the emission spectra, but also change the phonon relaxation rate and the site symmetry around the Dy3+ ions. The optimal condition is at y = 0.3 (Ba0.7Sr0.3La3.88Dy0.12(WO4)7), with CIE coordinates of (0.332, 0.367), corresponding to a near-white color.