Au3+/Au\mathrm{Au}^{3+} / \mathrm{Au}Au3+/Au
Mg2+/Mg\mathrm{Mg}^{2+} / \mathrm{Mg}Mg2+/Mg
Sn2+/Sn\mathrm{Sn}^{2+} / \mathrm{Sn}Sn2+/Sn
Al3+/Al\mathrm{Al}^{3+} / \mathrm{Al}Al3+/Al