Abstract: An air cell is disclosed, with a catalyst containing MnOx where 1.45.ltoreq.x.ltoreq.1.60, the material having X-ray diffraction peaks corresponding to the lattice constants of Mn.sub.5 O.sub.8.

Abstract: A solid electrolytic capacitor comprises an anode body made of a valve action metal the surface of which is coated with an anodically oxidized film, a manganese oxide layer formed thereon through repeatedly dipping, into a high viscosity slurry of manganese oxide producing solution consisting of Mn(NO.sub.3).sub.2 --Mn(CH).sub.2 --NH.sub.4 NO.sub.3 --H.sub.2 O followed by thermal decomposition, and a cathode layer formed thereon. Through the improvement of said solution a required amount of uniform and dense manganese oxide layer is produced with a minimum number of repetitions of the above process so that a solid electrolytic capacitor having an improved characteristic can be provided.

Abstract: In a solid electrolyte capacitor, a metallic cathode collector layer is in direct contact with an electrolyte layer which is formed of densely accumulated manganese dioxide particles of 0.1 - 50 .mu.m. The manganese dioxide layer is formed by performing pyrolysis of manganese nitrate in a semi-closed heating chamber of a radiant furnace to offer a resistance to the outflow from the chamber of gaseous decomposition products. The collector layer is formed by spraying, preferably by plasma spraying, of a metal powder typified by copper powder.

Abstract: A manganese dioxide layer of improved quality is formed on the surface of a dielectric oxide coating on a valve-metal substrate by repeating sequential procedures of immersing the substrate in an aqueous solution of manganese nitrate and heating the wet substrate to cause pyrolytic decomposition of manganese nitrate several times on condition that the heating is carried out at least once in a furnace wherein hot air flows and at least once in a semi-closed radiant furnace wherein the decomposition proceeds under a positive pressure of a small magnitude due to prolonged retention of gaseous decomposition products in the heating chamber.

Abstract: A manganese dioxide layer of improved quality is formed on an anodized valve metal substrate by repeating only a few times the steps of immersing the substrate in an aqueous solution of manganese nitrate and heating the wet substrate to cause pyrolytic decomposition of manganese nitrate to manganese dioxide in a semiclosed radiant furnace, wherein the decomposition proceeds under a positive pressure of a small magnitude due to prolonged retention of gaseous decomposition products.