Mechanism of the Luminescence Enhancement of SrSi2N2O2:Eu2+ Phosphor via Manganese Addition

The addition of Mn-O-based compounds during the solid-state synthesis of SrSi2N2O2:Eu2+ significantly increases the luminescence intensity of this phosphor. Hitherto, this effect was explained as the energy transfer between Eu2+ and Mn2+ ions. Using electron paramagnetic resonance and optical techniques, we show that Mn is not incorporated into the SrSi2N2O2 host; nevertheless, attempts to dope improve the luminescence quantum yield (QY) of this compound. Moreover, we found that codoping exertion with Mn ions in the synthesis process may also cause the enhancement of persistent luminescence and mechanoluminescence. It is also shown that the structure of the primary defects in SrSi2N2O2:Eu2+ does not change by adding Mn during the synthesis of this oxynitridosilicate, except their concentration. The changes of the radiative decay time of Eu2+ induced by attempts of codoping are responsible for the observed increase of the luminescence QY of this phosphor.