Abstract: The invention relates to a niobium powder capable of providing a capacitor having small amounts of leakage current, wherein the average nitrogen concentration in the layer of 50 to 200 nm from the surface to 0.29 to 4% by mass and preferably controlling that in the depth within 50 nm from the surface to 0.19 to 1% by mass, the sintered body, the formed body and the capacitor using the same.

Abstract: A niobium sintered body which is prepared in such a manner that a niobium powder is sintered at a temperature of 500° C. to 2000° C. and allowed to stand at a maximum sintering temperature for 60 minutes to 150 minutes in the course of sintering. The niobium sintered body of the present invention is characterized in that a product (CV) of a capacitance (C) per unit mass and a forming voltage (V) is 90,000 &mgr;F·V/g or more, and a value obtained by dividing a product of a mean particle diameter (D50) of a primary particle of said niobium powder and a leakage current (LC) by said CV is 5×10−4 &mgr;m·&mgr;A (&mgr;F·V) or less. And there can be provided a well-balanced capacitor with respect to a preferably low leakage current value regardless of the large capacitance, that is, a highly reliable capacitance.

Abstract: The present invention relates to a method for producing a niobium-oxide solid electrolytic capacitor comprising an anode being at least one member selected from niobium monoxide, niobium and an alloy mainly comprising niobium, or a mixture of niobium monoxide with niobium or an alloy mainly comprising niobium, which capacitor is formed by the electrolytic oxidation (electrochemical formation) of the anode; and the method comprising sequentially repeating twice or more a step of exposing a dielectric layer to a temperature of 200 to 1,000° C. before formation of a cathode and a step of re-electrochemically forming the dielectric layer.

Abstract: 1. A niobium powder for capacitors, wherein the chromium content is 50 ppm by mass or less, granulated product and sintered body thereof, and producing method of those; 2. a capacitor constructed by one part electrode formed of the niobium sintered body, another part electrode and a dielectric material interposed between two electrodes, and its producing method; and 3. an electronic circuit and electronic device using the capacitor. A capacitor having good voltage resistance properties can be manufactured by using the niobium sintered body for capacitors of the present invention, wherein the chromium content is 50 ppm by mass or less.

Abstract: A tantalum sintered body comprising a pore size distribution having a plurality of peaks wherein out of a plurality of peaks, two peaks having a largest relative intensity and a second largest relative intensity have a pore diameter of 0.2 to 0.7 &mgr;m and a pore diameter of 0.7 to 3 &mgr;m, having a volume of pore 10 mm3 or more including the volume of pore voids and a specific area of 0.2 to 7 m2/g, and having a CV value of 40,000 to 200,000 &mgr;FV/g when sintered at 1,300° C., and a capacitor using the sintered body.

Abstract: The invention relates to a niobium powder capable of providing a capacitor having small amounts of leakage current, wherein the average nitrogen concentration in the layer of 50 to 200 nm from the surface to 0.29 to 4% by mass and preferably controlling that in the depth within 50 nm from the surface to 0.19 to 1% by mass, the sintered body, the formed body and the capacitor using the same.

Abstract: A niobium sintered body which is prepared in such a manner that a niobium powder is sintered at a temperature of 500° C. to 2000° C. and allowed to stand at a maximum sintering temperature for 60 minutes to 150 minutes in the course of sintering. The niobium sintered body of the present invention is characterized in that a product (CV) of a capacitance (C) per unit mass and a forming voltage (V) is 90,000 &mgr;FV/g or more, and a value obtained by dividing a product of a mean particle diameter (D50) of a primary particle of said niobium powder and a leakage current (LC) by said CV is 5×10−4 &mgr;m&mgr;A (&mgr;FV) or less. And there can be provided a well-balanced capacitor with respect to a preferably low leakage current value regardless of the large capacitance, that is, a highly reliable capacitance.

Abstract: A nitrogen-containing niobium particle for capacitors is heated in an inert gas atmosphere, preferably in a vacuum, to obtain a niobium particle where the average nitrogen concentration in the region between a depth of 50 nm and a depth of 200 nm from the surface of the niobium particle is from 0.3 to 4% by mass and preferably, the average nitrogen concentration in the region from the particle surface to a depth of 50 nm is from 0.2 to 1% by mass. This niobium particle is sintered to obtain a sintered body. Using this niobium particle as one part electrode, a dielectric material is provided on the surface of the sintered body and a counter electrode is provided on the dielectric material, whereby a niobium capacitor reduced in the leakage current is obtained.

Abstract: A light-emitting diode comprises a first layer of Si-doped N-type Ga.sub.1-x Al.sub.x As, a second layer of Si-doped P-type Ga.sub.1-y Al.sub.y As and a third layer of P-type Ga.sub.1-z Al.sub.z As, in that order, in which the first and third layers have a higher Al concentration than the second layer, an Al concentration in the second layer decreases going from a first layer side to a third layer side, an Al concentration in a portion of the second layer in contact with the third layer is higher than an Al concentration value in a portion of the second layer in contact with the first layer minus 0.06, the second layer is formed to a thickness of approximately 8 .mu.m to 50 .mu.m, and light emission is via the first layer.