A comparative study of the spectroscopic properties of Mn4+ in the garnet Y2Mg3Ge3O12 and the commercial Mg28Ge7.55O32F15.04 phosphor

The spectroscopic properties of Mn4+ (3 d3) ions in the garnet Y2Mg3Ge3O12 and in the commercial Mg28Ge7.55O32F15.04 (MFG) phosphors are compared. We find that despite the differences in host crystal composition and crystal structures, the 4A2g→ 4T1g and 2Eg→4A2g optical transitions of the Mn4+ ion occur at similar energies. We provide some insights into the nature of chemical bonding that is responsible for the observed similarity in the spectroscopic data. Additionally, discussion is given to the site preference of the Mn4+ ion in the MFG host crystal.