Enhancement of near-infrared luminescence of Ni2+ in Li3Mg2SbO6 induced by Mn4+ sensitization

Ni 2+ -doped oxide phosphors feature an ultra-broad emission band covering 1000–1700 nm, showing remarkable application potential for broadband near-infrared (NIR) light sources. In this work, the phase structure, micromorphology and luminescence properties of the prepared Mn 4+ ,Ni 2+ co-doped Li 3 Mg 2 SbO 6 samples are systematically characterized. Spectral overlap between Mn 4+ emission and Ni 2+ excitation enables resonance energy transfer from Mn 4+ to Ni 2+ , resulting in an approximately 40-fold enhancement of Ni 2+ emission upon 315 nm excitation. The Mn 4+ → Ni 2+ energy transfer is verified to be performed by a long-range dipole–dipole interaction mechanism. At 423 K, the co-doped sample retains 20.20% of its room-temperature emission intensity, which is superior to the Ni 2+ singly doped counterpart (10.45%), indicating that the thermal stability is effectively improved by the Mn 4+ doping. Furthermore, an NIR phosphor-converted light-emitting diode (pc-LED) device is fabricated by coupling the optimized phosphor with a 320 nm near-ultraviolet (NUV) LED chip, which demonstrates favorable application potential in vein imaging, information encryption, non-destructive detection, and night vision. The result indicates that the Mn 4+ ,Ni 2+ dual-site co-doping strategy might be a feasible approach for optimizing Ni 2+ -activated near-infrared phosphors toward practical portable NIR light sources.