Hydrothermal synthesis and characterization of K chi MnO2 center dot gamma H2O

We report here the direct synthesis of a hexagonal form of manganese dioxide using mild hydrothermal methods. The reaction of potassium or sodium permanganate in water at 170 degrees C leads directly to potassium or sodium manganese dioxide, All(approximate to 0.25)MnO(2) .0.6H2O, with a R (3) over bar m rhombohedral structure like Li-x(H2O)TiS2 and a 7 Angstrom repeat distance indicative of a monolayer of water between the manganese dioxide layers. This manganese oxide reacts readily and reversibly with lithium ions.