Synthesis and luminescence properties of color-tunable Ba1−ySryLa4−xTbx(WO4)7 (x = 0.02–1.2, y = 0–0.4) phosphors

Ba1−ySryLa4−xTbx(WO4)7 (x = 0.02–1.2, y = 0–0.4) phosphors were prepared via a solid-state reaction and their photoluminescence properties were investigated. An analysis of the decay behavior indicates that the energy migration between Tb3+ ions is conspicuous in the 5D3 → 7F4 transition due to the cross-relaxation in BaLa4(WO4)7. A partial substitution of Ba2+ by Sr2+ can not only enhance the emission intensity but also increase the solid solubility of Tb3+ in Ba1−ySryLa4−xTbx(WO4)7. The emission intensity of the 5D4 → 7FJ (J = 4, 5, 6) transitions can be enhanced by increasing Sr2+ and Tb3+ concentrations, with the optimal conditions being x = 1.2, y = 0.4 (Ba0.6Sr0.4La2.8Tb1.2(WO4)7). Under near-UV excitation at 379 nm, the CIE color coordinates of Ba1−ySryLa4−xTbx(WO4)7 vary from blue (0.212, 0.181) at x = 0.04, y = 0, to green (0.245, 0.607) at x = 1.2, y = 0.4.