Reversible change in the valence state of manganese ions between tetra valent and divalent states on a sodium-mounted magnesium oxide surface

Paramagnetic manganese cation species have been investigated for Mn-added NaMgO by ESR. It has been found that a Mn4+ species different from those reported previously is present on the surface of NaMgO. The Mn4+ is converted to surface Mn2+ by degassing at 773 K and restores when exposed to oxygen.