ZnGa ₂ O ₄ :Ni ²⁺ glass-ceramic exhibits a second near-infrared emission band peaking at 1240 nm and persistent luminescence properties.

Broadband near-infrared (NIR) phosphors have received increasing attention for fabricating NIR light sources. In this article, based on our predictions of heavy Mn-doped models obtained using DFT calculations, we successfully synthesize and characterize manganese-based magnetoplumbite-type La(Zn,Mn)Al₁₁O₁₉ phosphors, which crystallize into a hexagonal structure with space-group P6₃/mmc. Under excitation at 450 nm, it was found that LaZn_0.7Mn_0.3Al₁₁O₁₉ and LaZn_0.2Mn_0.8Al₁₁O₁₉ had the optimal emission intensity and the maximum quantum efficiencies were 99% and 55%, respectively. An anomalous near-infrared (NIR) emission band at ∼730 nm is observed for the LaZnAl₁₁O₁₉ host with heavy Mn²⁺ doping. The density functional theory calculations and transient and steady-state luminescence investigation suggest that this unusual NIR emission band comes from the Mn²⁺–Mn²⁺ dimers. Moreover, the as-prepared phosphor, being integrated into high-powered photonic devices, could operate at high temperature without degeneration, due to the great advantage of the phosphor-in-glass (PiG) approach. Consequently, our study not only develops a viable strategy for synthesising innovative NIR phosphors, but also sheds light on the development of high-power photonic devices and procedures.

A novel Mn⁴⁺-activated oxide-fluoride perovskite KNaMoO₂F₄ red phosphor for wide gamut warm LED applications was prepared.

Mn⁴⁺ activated LaMgAl₁₁O₁₉ (LMA/Mn⁴⁺) with red emitting phosphor was obtained by sintering under air conditioning. The X-ray diffraction pattern Rietveld refinement results reveal that three six-fold coordinated Al sites are substituted by Mn⁴⁺ ions. Furthermore, the chemical valence state of manganese in the LMA host was further confirmed through X-ray photoelectron spectroscopy (XPS) and electron paramagnetic resonance (EPR). Photoluminescence emission (PL) and excitation (PLE) spectra of LMA/Mn⁴⁺ as well as the lifetime were measured, and the 663 nm emission is ascribed to the ²E_g→⁴A_2g from the 3d³ electrons in the [MnO₆]⁸⁻ octahedral complex. The emission spectrum matches well with the absorption of phytochrome. Temperature-dependent PL spectra show that the color changes of the phosphor at 420 K are 0.0110 for Δx and −0.0109 for Δy. Moreover, doping Zn²⁺ and Mg²⁺ ions in the host enhances the emission intensity of Mn⁴⁺ ions. These results highlight the potential of LMA/Mn⁴⁺ phosphor for a light-emitting diode (LED) plant lamp.