Lu₃(Al,Si)₅(O,N)₁₂:Ce³⁺ phosphors with broad emission band and high thermal stability for white LEDs

A yellow-orange emitting Lu₃Al_5-xSi_xO_12-xN_x:Ce³⁺ phosphor with excellent color rendering, high luminescent efficiency and high thermal stability was reported in this paper. It was synthesized by a conventional solid-state reaction method. The effect of Si⁴⁺-N^3- incorporation on the optical properties of Lu₃Al₅O₁₂:Ce³⁺ phosphor was investigated and compared to YAG:Ce³⁺ with the same compositions. Similarly, the addition of α-Si₃N₄ leads to a distinct redshift and broadening of photoluminescent spectrum, which is assigned to the increased covalency and crystal field strength caused by N^3-. Nevertheless, an excellent thermal stability and a higher integrated intensity presented by α-Si₃N₄-doped LuAG:Ce³⁺ are distinctive. Further, the emission intensity can be greatly enhanced by adding NaF flux. Finally, the white LED flat lamp with a CRI as high as 83 and a luminous efficiency of 85 lm/W is successfully realized by using a single LuAG-based oxynitride phosphor combined with a blue LED chip, which is completely feasible for general indoor illuminations to replace the traditional fluorescent or incandescent lamps.