Mn2+ doped CdAl2O4 phosphors with new structure and special fluorescence properties: experimental and theoretical analysis†
Abstract
Mn2+-activated CdAl2O4 phosphors with the new structure of space group R (no. 148) have been prepared by a high-temperature solid-state reaction and their luminescence properties have been investigated in detail. The reduction of Mn4+ to Mn2+ in air atmosphere has been observed in CdAl2O4 powders for the first time. The structural properties including the phase purity and structural parameters were analyzed through Rietveld analysis. The typical transitions of Mn2+ ions in emission and excitation spectra were observed both in MnCO3 and MnO2 prepared CdAl2O4:0.01Mn2+ phosphors, which means that the luminescent centers of Mn2+ ions were from the Mn4+ ions which were reduced. Meanwhile, the energy band structures of CdAl2O4 and CdAl2O4:Mn2+ were measured with an ultraviolet-visible diffuse reflection spectroscopy (UV-vis DRS), the electronic structures were calculated using the plane-wave density functional theory (DFT). The Mn2+ activated CdAl2O4:Mn2+ phosphor prepared in air atmosphere is a potential blue-green emitting phosphor.