Effects of Impurity Doping on the Luminescence Performance of Mn(4+)-Doped Aluminates with the Magnetoplumbite-Type Structure for Plant Cultivation

Mn(4+) activated LaMgAl(11)O(19) (LMA/Mn(4+)) 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 Mn(4+) 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/Mn(4+) as well as the lifetime were measured, and the 663 nm emission is ascribed to the (2)E(g)→(4)A(2g) from the 3d(3) electrons in the [MnO(6)](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 Zn(2+) and Mg(2+) ions in the host enhances the emission intensity of Mn(4+) ions. These results highlight the potential of LMA/Mn(4+) phosphor for a light-emitting diode (LED) plant lamp.