Abstract: To provide a sodium transition metal polyanion suitable as a cathode active material of a sodium secondary battery, and a simple method for producing it. A sodium transition metal polyanion, which has a purity of 90 mass % or higher, has a crystallite size of 90 ? or longer and 400 ? or shorter, and is represented by the formula Na3-xMPO4CO3 (M is at least one member selected from the group consisting of Fe, Mn, Ni and Co, and 0?x?2).

Abstract: The object of the present invention is to provide a solid electrolytic capacitor which can prevent an oxidation degradation of a solid electrolyte caused by heat stress and the like during packaging, which has low an ESR, and a production method of the same; in order to achieve this object, the solid electrolytic capacitor of the present invention includes in order an anode, a dielectric coat, a solid electrolyte layer, and a conductive paste layer, with a conductive polymer is used as the solid electrolyte, wherein the conductive paste layer contains acrylic resins and cellulose resins as a binder, and the thickness of the conductive paste layer is in a range of 20 to 40 &mgr;m.