Abstract: The present invention provides a Bi2223 oxide superconductor composed of Bi, Pb, Sr, Ln, Ca, Cu, and O, wherein the Ln is at least one selected from La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu, and the composition ratio of Sr to Ln is a composition ratio described below. The Bi2223 oxide conductor has a high critical current density in a magnetic field at low temperature and is capable of maintaining a high critical current density in a self magnetic field even at 77 K. Sr:Ln=(1?x):x (wherein 0.002?x?0.015) Also, the present invention provides a method for producing the Bi2223 oxide superconductor, the method including a step of ionizing a material containing elements, which constitute the Bi2223 oxide superconductor, in a solution; and a step of removing a solvent and causing a thermal decomposition reaction by spraying the solution into a high-temperature atmosphere to produce a powder containing atoms constituting the oxide superconductor.

Abstract: A method of synthesizing a superconducting material, comprising mixing starting materials comprising magnesium, boron, silicon and carbon; heating the mixture of starting materials to a temperature in the range between 650° C. and 2000° C. to produce a material comprising magnesium boride doped with silicon carbide; and cooling the resulting material to a temperature below the critical temperature of the material to render the material capable of superconducting.

Abstract: The invention offers a production method of a material powder of an oxide superconductor. The production method is provided with both a step of producing a dry powder by removing solvent from a solution containing elements for constituting the oxide superconductor and a step of producing oxides of the elements for constituting the oxide superconductor by scattering the dry powder in a high-temperature furnace. Provided with the above steps, the production method not only can achieve the uniform presence of the elements for constituting the oxide superconductor but also enables the mass production of the material powder.

Abstract: A method of producing a material of an oxide superconductor comprises the following steps: (a) in a solution, ionizing a material containing an atom for constituting the oxide superconductor, (b) by removing a solvent by spraying the solution in a first atmosphere, producing a material powder containing the atom for constituting the oxide superconductor, and (c) cooling the material powder in a second atmosphere into which a cooling gas is introduced. In this method, the concentration of carbon dioxide in the second atmosphere is lower than that in the first atmosphere, which contains the removed solvent component. The concentration of nitrogen oxide in the second atmosphere is lower than that in the first atmosphere, which contains the removed solvent component. The concentration of water vapor in the second atmosphere is lower than that in the first atmosphere, which contains the removed solvent component. These specifications enable the method to increase the density and purity of the oxide superconductor.

Abstract: A process for producing Bi-2223 high Tc superconductor in which fine MgO particles (<0.1 &mgr;m) are homogeneously distributed to provide flux pinning centers in Bi-2223 high Tc superconductor in order to give enhanced critical current density under magnetic field, as compared to the Bi-2223 high Tc superconductor without MgO dispersion, when processed under similar conditions. The process comprises mixing partially converted Bi-2223 powder and MgO fine particles, drying to give mixed powder, filling in silver tube, drawing, rolling and heat-treating at a temperature and for a time sufficient to form Bi-2223 high Tc superconductor in which fine MgO particles are homogeneously distributed.

Abstract: An improved method and apparatus for producing flexible fibers (30) of superconducting material includes a crucible (12) for containing a charge of the superconducting material. The material is melted in the crucible (12) and falls in a stream (18) through a bottom hole (16) in the crucible (12). The stream (18) falls through a protecting collar (22) which maintains the stream (18) at high temperatures. The stream (18) is then supplied through a downwardly directed nozzle (26) where it is subjected to a high velocity of a heated gas (36′) which breaks the melted superconducting material into ligaments which solidify into the flexible fibers (30). The fibers (30) are collected by directing them against a collection filter (32).

Abstract: The invention relates to a spray pyrolytic process for the preparation of multi-element metal oxide powders useful as precursors of high temperature superconductor ceramics. Aerosols of aqueous solutions containing corresponding metal salts admixed in the required stoichiometric proportion are sprayed through an independently operated hydrogen/oxygen flame in such a way that a flame temperature of 800.degree.-1100.degree. C. is maintained to form said powders. Any contact of the aerosols and powders generated during the process with carbon or carbon-containing compounds or materials is strictly avoided.

Abstract: A process for producing a sintered body from untra-fine superconductive particles. In the first step of this process, a ceramic precursor material containing yttrium, barium and copper cations, a nitrogen-containing material, a solvent, and an anion capable of participating in an anionic oxidation-reduction reaction with the nitrogen-containing material, is provided; the nitrogen-containing material contains at least three nitrogen atoms, at least one oxygen atom, and at least one carbon atom. In the second step of the process, droplets of such ceramic precursor material are formed. In the third step of the process, the droplets are dried until particles which contain less than about 15 weight percent of solvent are produced. In the fourth step of this process, such particles are ignited in an atmosphere which contains substantially less than about 60 weight percent of the solvent's saturation value in such atmosphere.

Abstract: The invention relates to a spray pyrolyric process for the preparation of multi-element metal oxide powders useful as precursors of high temperature superconductor ceramics. Aerosols of aqueous solutions containing corresponding metal salts admixed in the required stoichiometric proportion are sprayed through an independently operated hydrogen/oxygen flame in such a way that a flame temperature of 800.degree.-1100.degree. C. is maintained to form said powders. Any contact of the aerosols and powders generated during the process with carbon or carbon-containing compounds or materials is strictly avoided.

Abstract: Process for preparing a high-T.sub.c superconductor as a precursor material for the oxide-powder-in-tube method (OPIT). The present invention relates to a process for preparing a high-T.sub.c superconductor as a precursor material for the oxide-powder-in-tube method, which involves mixing the oxides of the elements Bi, Sr, Ca and Cu and completely melting them at temperatures of .gtoreq.1000.degree. C., then casting the melt onto a substrate which is kept at room temperature, and disintegrating the cooled melt block and grinding it into a powder.

Abstract: A process for the preparation of amorphous precursor powders for Pb-doped Bi.sub.2 Sr.sub.2 Ca.sub.2 Cu.sub.3 O.sub.x (2223) includes a freeze-drying process incorporating a splat-freezing step. The process generally includes splat freezing a nitrate solution of Bi, Pb, Sr, Ca, and Cu to form flakes of the solution without any phase separation; grinding the frozen flakes to form a powder; freeze-drying the frozen powder; heating the dried powder to form a dry green precursor powders; denitrating the green-powders; heating the denitrated powders to form phase-clean Bi-2223 powders. The grain boundaries of the 2223 grains appear to be clean, leading to good intergrain contact between 2223 grains.

Abstract: An improved method for the efficient incorporation of a metal such as silver in a superconducting material includes blending the metal with a high temperature superconductor or precursor powder and consolidating the same into pellets. The pellets are charged directly into a heating assembly where it is melted and heated sufficiently to a uniform temperature prior to fiberization. Droplets of the melted blend fall through a collar into a nozzle where they are subjected to a high velocity gas to break the melted material into ligaments which solidify into improved flexible fibers having the metal homogeneously disThis invention was made with Government support under a contract with the Department of Energy (DOE) and Ames Laboratory, Contract No. SC-91-225, our reference No. CRD-1272. The Government has certain rights in this invention.