Two new rare-earth oxyborates Ba 4 BiTbO(BO 3 ) 4 and Ba 1.54 Sr 2.46 BiTbO(BO 3 ) 4 and luminescence properties of the Ba 4 BiTb 1- x Eu x O(BO 3 ) 4 phosphors.

Single crystals of two new terbium oxyborates Ba 4 BiTbO(BO 3 ) 4 and Ba 1.54 Sr 2.46 BiTbO(BO 3 ) 4 were obtained by the high-temperature solution method. They crystallize in the hexagonal P 6 3 / mmc group ( Z = 2) with lattice parameters of a = 5.41865(9) Å, c = 26.3535(5) Å, V = 670.12(3) Å 3 and a = 5.36534(19) Å, c = 26.0661(10) Å, V = 649.83(5) Å 3 , respectively. Their crystal structures feature two kinds of layers: [Tb(BO 3 ) 2 ] n 3 n - formed by corner-sharing TbO 6 octahedra and BO 3 triangles, as well as [Bi(BO 3 ) 2 O] n 5 n - consisting of Bi 2 O 13 dimers and BO 3 groups, with alkali-earth cations sitting inside and between the layers. In addition, solid solutions of Ba 4 BiTb 1- x Eu x O(BO 3 ) 4 (0 ≤ x ≤ 0.2) were prepared via the solid-state reaction method. The obtained products were characterized by powder XRD, SEM, IR/Raman, XPS, DRS, and luminescence spectroscopy. It was found that as the Eu 3+ doped content varies from x = 0 to 0.2, the emission color of the Ba 4 BiTb 1- x Eu x O(BO 3 ) 4 phosphors can be adjusted from cyan to near-white and then to orange-red or from green to orange and then to red under the excitation of 349 and 377 nm, respectively. Furthermore, the emission intensities and chromaticity coordinates were found to be sensitive to the temperature for the phosphor Ba 4 BiTb 0.999 Eu 0.001 O(BO 3 ) 4 upon 377 nm excitation. The above results demonstrate that Ba 4 BiTb 1- x Eu x O(BO 3 ) 4 phosphors have potential as multifunctional materials for solid-state lighting and temperature sensing applications.