Luminescence properties of a non-rare-earth doped oxyfluoride LiAl4O6F:Mn4+ red phosphor for solid-state lighting

Abstract

A novel red phosphor LiAl4O6F:Mn4+ (in brief LAOF:Mn4+) is prepared by a solid-state reaction method. X-ray diffraction (XRD), scanning electron microscope (SEM), photoluminescence excitation and emission spectra and decay curves are used to characterize the properties of LAOF:Mn4+ phosphors. Under 450 nm excitation, it is observed an intense red emission peak around 662 nm, which corresponds to 2Eg-4A2g transition of Mn4+ in LAOF:Mn4+ phosphor. The optimum molar doping concentration of Mn4+ ions in LAOF host is 0.2%. On the basis of the temperature-dependence luminescence spectra, the activation energy is about 0.32 eV for the LAOF:Mn4+ phosphor. The crystal field strength (Dq) and the Racah parameters (B and C) are carefully calculated to evaluate the nephelauxetic effect of Mn4+ in the LAOF host. The excellent luminescent properties of LAOF:Mn4+ suggest this material could be a promising deep-red phosphor for solid-state lighting.