Abstract: A method of texturing a multifilamentary article having filaments comprising a desired oxide superconductor or its precursors by torsionally deforming the article is provided. The texturing is induced by applying a torsional strain which is at least about 0.3 and preferably at least about 0.6 at the surface of the article, but less than the strain which would cause failure of the composite. High performance multifilamentary superconducting composite articles having a plurality of low aspect ratio, twisted filaments with substantially uniform twist pitches in the range of about 1.00 inch to 0.01 inch (25 to 0.25 mm), each comprising a textured desired superconducting oxide material, may be obtained using this texturing method. If tighter twist pitches are desired, the article may be heat treated or annealed and the strain repeated as many times as necessary to obtain the desired twist pitch.

Abstract: An aspected multifilamentary oxide article is provided having a plurality of aspected filaments including a metal oxide and extending continuously for the length of the article. A constraining member substantially surrounds each filament, wherein each of the filaments has an average transverse cross-sectional thickness less than about 35 &mgr;m and an average variation in cross-section along its length of less than about 10%. The article exhibits superior filament uniformity, hardness, and oxide density and texture.

Abstract: A novel process of the production and processing of high quality, high Tc (Bi,Pb)SCCO superconductors starts with fabrication of a precursor article including selected intermediate phases with desired chemical and structural properties. The precursor fabrication includes introducing the reacted mixture having a dominant amount of the tetragonal BSCCO phase into a metal sheath, and sealing the reacted mixture within said sheath, heating the mixture at a second selected processing temperature in an inert atmosphere with a second selected oxygen partial pressure for a second selected time period, the second processing temperature and the second oxygen partial pressure being cooperatively selected to form a dominant amount of an orthorhombic BSCCO phase in the reacted mixture.

Abstract: The invention features high performing composite superconducting oxide articles that can be produced from OPIT precursors substantially without poisoning the superconductor. In general, the superconducting oxide is substantially surrounded by a matrix material. The matrix material contains a first constraining material including a noble metal and a second metal. The second metal is a relatively reducing metal which lowers the overall oxygen activity of the matrix material and the article at a precursor process point prior to oxidation of the second metal. The second metal is substantially converted to a metal oxide dispersed in the matrix during or prior to a first phase conversion heat treatment but after formation of the composite, creating an ODS matrix.

Abstract: A method for preparing a BSCCO-2223 oxide superconducting article includes annealing an oxide superconductor article comprised of BSCCO-2223 oxide superconductor at a temperature selected from the range of about 500° C.≦T≦787° C. and an annealing atmosphere having an oxygen pressure selected from within the region having a lower bound defined by the equation, PO2(lower)≧3.5×1010exp(−32,000/T+273) and an upper bound defined by the equation, PO2(upper)≦1.1×1012exp(−32,000/T+273). The article is annealed for a time sufficient to provide at least a 10% increase in critical current density as compared to the critical current density of the pre-anneal oxide superconductor article. An oxide superconductor having the formula Bi2−yPbySr2Ca2Cu3O10+x, where 0≦x≦1.5 and where 0≦y≦0.6 is obtained, the oxide superconductor characterized by a critical transition temperature of greater than 111.0 K, as determined by four point probe method.

Abstract: A cabled conductor is provided for use in a cryogenically cooled circuit including refrigeration having a predetermined operating temperature and efficiency. The conductor includes multiple conductor strands cabled about the longitudinal axis of the conductor at a preselected cabling period, each strand including a composite of superconducting ceramic in intimate contact with conductive matrix material. Each filament has high performance regions in which the filament material is well-textured with its preferred direction aligned perpendicular to the widest longitudinal cross-section of the conductor alternating with poorly superconducting regions which are at least about half the diameter of a filament in length and in which the superconducting ceramic filament is strained by transposition in excess of its critical strain limit. In the poorly superconducting regions, the conductive matrix material provides an alternate current path.

Abstract: A method is described to prepare a highly textured oxide superconductor article in a single deformation-sinter process. A precursor article including a plurality of filaments comprising a precursor oxide having a dominant amount of a tetragonal BSCCO 2212 phase and a constraining member substantially surrounding each of the filaments is provided. Each of the filaments extends along the length of the article. The oxide article is subjected to a heat treatment at an oxygen partial pressure and temperature selected to convert a tetragonal BSCCO 2212 oxide into an orthorhombic BSCCO 2212 oxide and, thereafter, roll worked in a high reduction draft in a range of about 40% to 95% in thickness so that the filaments have a constraining dimension is substantially equivalent to a longest dimension of the oxide superconductor grains. The rolled article is sintered to obtain a BSCCO 2223 oxide superconductor.

Abstract: A cabled conductor comprises a plurality of transposed strands each comprising one or more preferably twisted filaments preferably surrounded or supported by a matrix material and comprising textured anisotropic superconducting compounds which have crystallographic grain alignment that is substantially unidirectional and independent of the rotational orientation of the strands and filaments in the cabled conductor. The cabled conductor is made by forming a plurality of suitable composite strands, forming a cabled intermediate from the strands by transposing them about the longitudinal axis of the conductor at a preselected strand lay pitch, and, texturing the strands in one or more steps including at least one step involving application of a texturing process with a primary component directed orthogonal to the widest longitudinal cross-section of the cabled intermediate, at least one such orthogonal texturing step occurring subsequent to said strand transposition step.

Abstract: The combination of one or more high reduction drafts with controlled, low back tensions increases the range of deformation conditions over which dimensional tolerances and Je may be optimized. The method comprises the steps of: first, providing a precursor article comprising a metal matrix surrounding a plurality of filaments extending along the length of the article and comprising precursors to a desired superconducting ceramic; next, roll working the precursor article during a breakdown stage at a back tension less than the elastic to plastic transition threshold of the composite during at least one high reduction roll working draft, and, then, sintering the rolled article to obtain the desired superconducting ceramic. In a preferred embodiment, the rolling step further comprises rolling the article at a front tension less than the elastic to plastic transition threshold of the rolled, unsintered article.

Abstract: A method for preparing an oxide superconductor cable includes transposing a plurality of oxide superconductor strands along a longitudinal axis so as to form a cable and exposing the cable to a two step heat treatment after cabling of the oxide strands, the heat treatment comprising, (a) heating the cable to and maintaining the cable at a first temperature sufficient to partially melt the article, such that a liquid phase co-exists with the desired oxide superconductor phase; and (b) cooling the cable to and maintaining the cable at a second temperature sufficient to substantially transform the liquid phase into the desired oxide superconductor.

Abstract: The present invention provides a (Bi,Pb)SCCO-2223 oxide superconductor composite which exhibits improved critical current density and critical current density retention in the presence of magnetic fields. Retention of critical current density in 0.1 T fields (77 K, ⊥ ab plane) of greater than 35% is disclosed. Significant improvements in oxide superconductor wire current carrying capacity in a magnetic field are obtained by subjecting the oxide superconductor composite to a post-processing heat treatment which reduces the amount of lead in the (Bi,Pb)SCCO-2223 phase and forms a lead-rich non-superconducting phase. The heat treatment is carried out under conditions which localize the lead-rich phase at high energy sites in the composite.

Abstract: A process for increasing the resistivity of a HTS oxide composite sheath including heating a superconductive HTS oxide composite, the composite including a sheath including silver, in the presence of mercury at temperatures sufficient to form a silver--mercury alloy is provided together with a HTS oxide composite which includes a high temperature superconductor oxide core surrounded by a metallic sheath, the metallic sheath including silver and mercury.Also provided is a process for preparing a HTS oxide composite having an enhanced transport critical current density including placing the HTS oxide composite within a sealed, evacuated container, and, heating the HTS oxide composite for time and at temperatures sufficient for enhancement of transport critical current density in comparison to the transport critical current density of the HTS oxide composite prior to the heating.

Abstract: A novel process of the production and processing of high quality, high T.sub.c BSCCO or (Bi,Pb)SCCO superconductors starts with fabrication of a forming a bundle including a plurality of billets, each billet containing at least one filament comprising a dominant amount of an tetragonal BSCCO phase with selected intermediate phases, and substantially surrounded by a constraining metal. The bundle is thermomechanically consolidated to form a multifilamentary precursor article by applying pressure and heat to the bundle under conditions cooperatively selected to cause interdiffusion of said constraining metal at the interfaces between said metal and said filaments and substantially complete elimination of voids in said bundle, and the consolidation step is completed before any high strain longitudinal deformation is performed on the bundle.

Abstract: A multifilamentary superconducting composite article comprising multiple substantially electrically decoupled domains, each including one or more fine, preferably twisted filaments of a desired superconducting oxide material. In a preferred embodiment, the article comprises a matrix, which substantially comprises a noble metal, a conductive jacketing layer surrounding the matrix, a plurality of discrete filament decoupling layers, each comprising an insulating material, disposed within the matrix to separate the matrix into a plurality of substantially electrically decoupled domains; a plurality of filaments, each comprising a desired superconducting oxide, which are disposed within and essentially encapsulated by the matrix and chemically isolated thereby from the decoupling layers, each of the electrically decoupled domains containing at least one filament.

Abstract: A method of forming a textured superconductor wire includes constraining an elongated superconductor precursor between two constraining elongated members placed in contact therewith on opposite sides of the superconductor precursor, and passing the superconductor precursor with the two constraining members through flat rolls to form the textured superconductor wire. The method includes selecting desired cross-sectional shape and size constraining members to control the width of the formed superconductor wire. A textured superconductor wire formed by the method of the invention has regular-shaped, curved sides and is free of flashing. A rolling assembly for single-pass rolling of the elongated precursor superconductor includes two rolls, two constraining members, and a fixture for feeding the precursor superconductor and the constraining members between the rolls.

Abstract: An oxide superconductor article comprises silver and an oxide superconductor having the formula Bi.sub.2-y Pb.sub.y Sr.sub.2 Ca.sub.2 O.sub.10+x, where 0.ltoreq.x.ltoreq.1.5, and 0.3.ltoreq.y.ltoreq.0.4, the oxide superconductor characterized by a critical current transition temperature of greater than 111.0 K as defined by zero resistance by a four point linear probe method with zero resistance corresponding to a resistivity of less that 10.sup.-8 .OMEGA.-cm.

Abstract: A novel process of the production and processing of high quality, high T.sub.c (Bi,Pb)SCCO superconductors starts with fabrication of a precursor article including selected intermediate phases with desired chemical and structural properties. The precursor fabrication includes introducing the reacted mixture having a dominant amount of the tetragonal BSCCO phase into a metal sheath, and sealing the reacted mixture within said sheath, heating the mixture at a second selected processing temperature in an inert atmosphere with a second selected oxygen partial pressure for a second selected time period, the second processing temperature and the second oxygen partial pressure being cooperatively selected to form a dominant amount of an orthorhombic BSCCO phase in the reacted mixture.

Abstract: The invention provides a superconducting ceramic laminate including a superconducting tape mechanically coupled to, and compressively strained to 0.1% or more under a predetermined load by, at least one cladding tape. The material and thickness of the cladding tape or tapes are selected relative to the material and thickness of the superconducting tape to locate the neutral axis so that, under a predetermined heavy load, the maximum compressive strain on any superconducting portion of the superconducting tape is less than the critical compressive strain and the maximum tensile strain on any superconducting portion of the superconducting tape under a predetermined load is less than the critical tensile strain. By "heavy load" is meant a load on the laminate equivalent to a load on the unlaminated superconducting tape selected for the laminate including a surface bend strain on the unlaminated superconducting tape of at least 0.1%.

Abstract: The present invention provides a (Bi,Pb)SCCO-2223 oxide superconductor composite which exhibits improved critical current density and critical current density retention in the presence of magnetic fields. Retention of critical current density in 0.1 T fields (77 K, .perp. ab plane) of greater than 35% is disclosed. Significant improvements in oxide superconductor wire current carrying capacity in a magnetic field are obtained by subjecting the oxide superconductor composite to a post-processing heat treatment which reduces the amount of lead in the (Bi,Pb)SCCO-2223 phase and forms a lead-rich non-superconducting phase. The heat treatment is carried out under conditions which localize the lead-rich phase at high energy sites in the composite.

Abstract: A process for manufacturing superconducting magnetic coils from strain-tolerant, superconducting multi-filament composite conductors is described. The method involves winding the precursor to a multi-filament composite conductor and an insulating material or its precursor around a mandrel in order to form a coil, and then exposing the coil to high temperatures and an oxidizing environment. The insulating material or its precursor is chosen to permit exposure of the superconductor precursor filaments to the oxidizing environment, and to encase the matrix-forming material enclosing the filaments, which is reversibly weakened during processing.