Mn4+ luminescence in 2MgO • GeO2 and 2MgO • GeO2 • MgF2

The oxidation state of the Mn activator in 2MgO . GeO2, 2MgO . GeO2. MgF2 was shown to be 4+. The observed luminescence behavior of these phosphors was accounted for by a large crystal-held splitting. The T-2(1) and E-2 excited states of Mn4+ were found to be close in lifetime (100-120 mu s). The slower luminescence decay in magnesium fluorogermanate is attributable to the energy transfer between the activator and electron traps through the conduction band.