Effects of Impurity Doping on the Luminescence Performance of Mn4+-Doped Aluminates with the Magnetoplumbite-Type Structure for Plant Cultivation

Abstract

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 2Eg→4A2g 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.

Phosphorescence in Mn4+-DopedR+/R2+Germanates (R+= Na+or K+,R2+= Sr2+)

“…The emission peak at 663 nm is associated with 2 E g → 4 A 2g relaxation of Mn 4+ and the peak position is in good agreement with previous reports of Mn 4+ phosphors. − The position of the emission peak is known to be independent on the crystal field strength but affected by the covalency of Mn–ligand bonds …”

Synthesis, Crystal Structure, and Photoluminescence Characteristics of High-Efficiency Deep-Red Emitting Ba2GdTaO6:Mn4+ Phosphors

“…Under 358 nm excitation, the IQE of the BGT:0.6%Mn 4+ sample was measured using an integrating sphere, as shown in Figure a, which could be calculated by the following equation where η is the IQE; L S is the emission spectrum of the sample; and E S and E R are the spectra of the excitation light with the BGT:0.6%Mn 4+ sample and only with BaSO 4 reference, respectively. Thus, the calculated IQE was 44%, which was higher than that of the recently reported Mn 4+ -activated red-emitting phosphors, such as Mg 7 Ga 2 GeO 12 :Mn 4+ (IQE: 28.13%), La­(MgTi) 1/2 O 3 :Mn 4+ (IQE: 27.2%), and SrLaScO 4 :Mn 4+ (IQE: 12.2%). − Furthermore, we also measured the IQEs for other samples of BGT: x Mn 4+ phosphors using the same integrating sphere method.…”

“…49,59 Distinctly, the decay times gradually decreased with x increasing from 0.2 to 1.2 mol %, which was due to the increased possibility of a nonradiative energy migration between the Mn 4+ ions with increasing Mn 4+ concentration. 60 Under 358 nm excitation, the IQE of the BGT:0.6%Mn 4+ sample was measured using an integrating sphere, as shown in Figure 7a, which could be calculated by the following equation 61…”

Enriching the Deep-Red Emission in (Mg, Ba)3M2GeO8: Mn4+ (M = Al, Ga) Compositions for Light-Emitting Diodes

“…39 The slight reduction in the D q /B values of MAG: Mn 4+ compared to MGG: Mn 4+ can be attributed to the lower average Al−O bond length of MAG: Mn 4+ . 49 High-temperature PL analysis was carried out for the two compositions MAG: Mn 4+ , 0.27Ba 2+ and MGG: Mn 4+ , 0.13Ba 2+ . The temperature was varied from 300 to 453 K, and the PL emission spectra were recorded under UV excitation.…”