A new melilite-type rare-earth borate CdTbGaB(2)O(7) and multicolor tunable emission in the CdTb(1−x)Sm(x)GaB(2)O(7) (0 ≤ x ≤ 0.2) phosphors

A new mixed metal borate, CdTbGaB(2)O(7), was successfully synthesized using the high-temperature solution method and its crystal structure was determined by single-crystal X-ray diffraction with the following unit-cell data: P4̄2(1)m, a = b = 7.3487(1) Å, c = 4.7247(1) Å, V = 255.150(9) Å(3), and Z = 2. It belongs to a new member of the melilite family, which features a 3D framework consisting of alternately stacked [Ga(B(2)O(7))](n)(5n−) tetrahedral layers and (Cd(2+)/Tb(3+)) cationic layers that are interconnected via B(Ga)–O–(Cd/Tb) bridges. In addition, the solid solutions of CdTb(1−x)Sm(x)GaB(2)O(7) (0 ≤ x ≤ 0.2) were prepared via the solid-state reaction method. The combined techniques of XRD, SEM, IR/Raman, XPS and PLE/PL were employed to characterize the products. It was found that the CdTb(1−x)Sm(x)GaB(2)O(7) phosphors simultaneously showed green emission of Tb(3+) at 545 nm and orange emission of Sm(3+) at 603 nm under excitation at 370 nm. The emission color can be adjusted from green to orange-red by varying the Sm(3+) doped content via an energy transfer mechanism. For CdTb(0.995)Sm(0.005)GaB(2)O(7), a QY of 13.22% was obtained, and its emission intensity at 423 K was 94% of that at 303 K. These results show that the prepared materials can act as potential color-tunable phosphors for UV w-LEDs.