Mn⁴⁺, Bi³⁺ Co-Doped K_0.5La_0.5SrMgTeO₆ Far-Red Emitting Phosphor

A series of Mn4+ doped KmLamSr2-2mMgTeO6 phosphors and Mn4+, Bi3+ co-doped phosphors were prepared by high-temperature solid-state reaction method. It is found that the non-luminous Sr2MgTeO6: Mn4+ begins to glow when the Sr2+ sites are partially replaced by K+ and La3+ ions. The K0.5La0.5SrMgTeO6: Mn4+ phosphor gives the strongest emission peaking at 692 nm, in which half of the Sr2+ ions are replaced by La3+ and K+ ions. The optimal doping concentration of Mn4+ in K0.5La0.5SrMgTeO6 is 0.7% in mole. As the concentration of Mn4+ continues to increase, the dipole-dipole interaction-induced luminescence concentration quenching occurs. Moreover, the emission intensity of the phosphor can be further increased by 69% when co-doping Bi3+ with a concentration of 1% in a mole. The properties of the developed phosphor indicate that it has potential application prospects in plant growth LED.