Abstract: A capacitor element including at least an anode body composed of a sintered compact containing tungsten as a main component, a dielectric layer with a smooth surface formed by chemical conversion of the surface of the anode body, and a semiconductor layer laminated on the dielectric layer. The capacitor is obtained by a production method which includes the steps of chemically converting the surface layer of the tungsten powder sintered compact into the dielectric layer in an aqueous solution containing 0.05 to 12% by mass of an oxidant composed of an oxygen-containing compound at a solution temperature of 62° C. or less, and removing all or most of water adhering to the inner surface of pores at a temperature of less than the boiling point of water, followed by drying at a temperature of not less than the boiling point of water.

Abstract: An anode body for a capacitor formed by subjecting the sintered body which is obtained by sintering the molded body of tungsten powder to chemical conversion treatment, which anode body is doped with potassium in the amount of 0.003 to 0.3 mass %; a method of producing an anode body for a capacitor formed by subjecting the sintered body which is obtained by sintering the molded body of tungsten powder to chemical conversion treatment, including a process of doping the anode body with potassium in an amount of 0.003 to 0.3 mass %; and a solid electrolytic capacitor using the anode body.

Abstract: Disclosed is (1) an anode body for a capacitor including a tungsten sintered body containing 15 to 3,000 ppm by mass of phosphorus element; (2) a method for producing an anode body for a capacitor which includes producing a molded body of tungsten powder in which a phosphorus source is mixed and sintering the molded body to thereby incorporate 15 to 3,000 ppm by mass of phosphorus element in the anode body; (3) a capacitor element including the anode body; and (4) a capacitor including the capacitor element.

Abstract: An anode body for a capacitor formed by subjecting the sintered body which is obtained by sintering the molded body of tungsten powder to chemical conversion treatment, which anode body is doped with potassium in the amount of 0.003 to 0.3 mass %; a method of producing an anode body for a capacitor formed by subjecting the sintered body which is obtained by sintering the molded body of tungsten powder to chemical conversion treatment, including a process of doping the anode body with potassium in an amount of 0.003 to 0.3 mass %; and a solid electrolytic capacitor using the anode body.

Abstract: A capacitor element including at least an anode body composed of a sintered compact containing tungsten as a main component, a dielectric layer with a smooth surface formed by chemical conversion of the surface of the anode body, and a semiconductor layer laminated on the dielectric layer. The capacitor is obtained by a production method which includes the steps of chemically converting the surface layer of the tungsten powder sintered compact into the dielectric layer in an aqueous solution containing 0.05 to 12% by mass of an oxidant composed of an oxygen-containing compound at a solution temperature of 62° C. or less, and removing all or most of water adhering to the inner surface of pores at a temperature of less than the boiling point of water, followed by drying at a temperature of not less than the boiling point of water.