The nephelauxetic fonction he applied to the luminescence of Mn4+ and Mn5+ ions in oxides and oxyhalides

It was shown recently that the emission energy of octahedrally-coordinated Mn4+ ions in 101 oxides and 51 fluorides can be estimated from the nephelauxetic function he. Here, we extent this concept to Mn4+ ions incorporated in oxyfluorides and in compounds that do not primarily offer octahedral positions for this dopant in their crystal structure. We show that Mn4+ tends to reconstitute a 6-fold coordinated environment in these crystal lattices and tends to reconstitute either pure [MnF6]2- or pure [MnO6]8- octahedra in oxyfluorides, depending on the O/F ratio in the virgin host lattice. We also show that the “he model” can be used to estimate the energy of the NIR emitting 1E state of tetrahedrally-coordinated Mn5+ with an accuracy of ±350 cm−1. •Mn4 reconstitutes a 6-coordinated site in compounds that do not offer octahedral positions.•Mn4+ reconstitutes either pure [MnF6]2- or pure [MnO6]8- octahedral units in oxyfluorides.•The he model applies to Mn5+ ions in solids.