Far-red emitting Mg2La3NbO9:Mn4+ powder phosphor: Synthesis and luminescence properties

Abstract

Novel Mg2La3NbO9:Mn4+ powder phosphors are successfully synthesized by the high-temperature solid-state reaction method under ambient air. The crystal structure, morphology, decay lifetimes, time-resolved emission spectra, and luminescence properties are investigated. The excitation spectrum of Mg2La3NbO9:Mn4+ phosphor monitored at 708 nm is observed in the region from 210 nm to 600 nm. Mg2La3NbO9:Mn4+ phosphor with excitation at the ultraviolet (UV) and blue light can emit the far-red emission with the emission band peaking at ~708 nm because of the 2E → 4A2 transition of Mn4+ and the corresponding chromaticity coordinates (0.7322, 0.2678). The optimal doping concentration of Mn4+ ion is ~0.6 mol%. The decay lifetime of Mg2La3NbO9:xMn4+ phosphors decrease from 1.143 ms to 1.099 ms with increasing the Mn4+ ion concentration from 0.2 mol% to 1.0 mol%. The good thermal stability of Mg2La3NbO9:Mn4+ phosphor is confirmed by the temperature-dependent emission spectra. The luminous mechanism of Mg2La3NbO9:Mn4+ phosphor is explained by using the Tanabe Sugano energy level diagram of Mn4+ ion. All the experimental results imply that Mg2La3NbO9:Mn4+ phosphor has a potential application in the white light-emitting diodes (LEDs) field.