(3+1)-Dimensional Modulated Structure and Tb3+-Doped Luminescence for Vanadate Na3La(VO4)2

A modulated structure with symmetrical characteristic higher than three-dimensional is a fascinating crystallographic type, and it is randomly encountered by researchers. Herein, we prepared 0.1 mm level single crystals of Na3La(VO4)2 and determined its structure to be a (3 + 1)-dimensional modulated structure using the X-ray diffraction analysis method for single crystals. Its super space group was determined to be Pca21(0β0)000. On the other hand, we introduced Tb3+ into the Na3La(VO4)2 host lattice to fabricate phosphors Na3La1-x(VO4)2:xTb3+ and studied their photoluminescence properties. Interestingly, for the strong absorption of the Na3La(VO4)2 host lattice in the range of 200–400 nm, the traditional 330–385 nm light is unable to efficiently excite Tb3+ ions in the Na3La(VO4)2 host to generate luminescence of Tb3+. Instead, Na3La1–x(VO4)2:xTb3+ is suitable to be excited by 487 nm to generate emitting light at 543, 584, and 622 nm, due to Tb3+ characteristic 4f → 4f transitions of 5D4 → 7FJ (J = 5, 4, 3). Hence, the Tb3+-doped Na3La(VO4)2 phosphors have potential applications for white-light-emitting diodes.