Barium Manganites

It is probable that many natural double oxides are really manganites very rich in manganese, for example psilomelane, and varvacite, Mn₉O₁₈Ba.3H₂O. Several manganites have been prepared artificially. The compound BaO.MnO₂ is stable above 1100° C. or below 1000° C., and the compound BaO.2MnO₂ between these two temperatures. The latter is also formed along with manganese dioxide by heating barium permanganate at 320° C., and if the heating be prolonged, a manganite still richer in manganese, BaO.7MnO₂, is obtained. The compounds, BaO.5MnO₂ and BaO.MnO₂.H₂O, have also been obtained.