Synthesis, color-tunable emission, thermal stability, luminescence and energy transfer of Sm3+ and Eu3+ single-doped M3Tb(BO3)3 (M = Sr and Ba) phosphors

A series of new tunable emission phosphors of Sm3+ and Eu3+ single-doped M3Tb(BO3)3 (M = Sr and Ba) phosphors were synthesized by the solid-state reaction. Crystallization behavior and structure, reflectance spectral properties, luminescence properties, energy transfer, lifetimes, temperature-dependent luminescence properties and CIE chromaticity coordinate of M3Tb(BO3)3:Ln3+ (M = Sr and Ba, Ln = Sm and Eu) were systematically investigated. M3Tb(BO3)3 (M = Sr and Ba) crystallizes in a rhombohedral cell with space group R by Rietveld structure refinement of the obtained phosphors with the standard data of Ba3Dy(BO3)3. Sr3Tb(BO3)3 and Ba3Tb(BO3)3 emit yellowish-green emission with the main peak around 555 and 550 nm, respectively, which originates from the 5D4 → 7F4 transition of Tb3+, and M3Tb(BO3)3:Ln3+ (Ln = Sm and Eu) phosphors show intense yellowish-green, yellow, orange and red emission with increasing Ln3+ concentration under 274 and 286 nm excitation. The orange-red/red emissions show peak maxima at 613 nm (Sr3Tb(BO3)3:Sm3+), 627 nm (Sr3Tb(BO3)3:Eu3+), 607 nm (Ba3Tb(BO3)3:Sm3+) and 625 nm (Ba3Tb(BO3)3:Eu3+), and are due to the efficient energy transfer of Tb3+–Sm3+ and Tb3+–Eu3+. The temperature-dependent luminescence properties of M3Tb(BO3)3:Ln3+ are characterised by good thermal stabilities up to 150 °C, up to 72.8%. However, due to the defect in the host of the Sr3Tb0.99(BO3)3:0.01Sm3+ phosphor, an amazing and interesting phenomenon can be observed that the emission intensity is enhanced constantly with increasing temperature.