Abstract: A superconducting article having a high bulk sheath resistivity, and methods of manufacture of such an article. High-temperature superconductor filaments are disposed in a ductile matrix comprising a high silver content. The matrix is then coated with a solute and heated to a temperature high enough to allow the solute to diffuse into the matrix, but not high enough to allow substantive degradation or poisoning of the superconductor. After diffusion and cooling, the matrix comprises a silver alloy having a higher bulk resistivity than the pure silver.

Abstract: A method of making a high density Mg—B superconducting article includes providing a packed powder sheath, said powder comprising a source of magnesium and boron, subjecting the packed powder sheath to a symmetric deformation, said deformation selected to elongate the packed powder sheath to form a wire while retaining the free flow of particles within the powder core, subjecting the wire to high reduction rolling, said high reduction rolling selected to reduce the wire thickness by 40 to 95% and heating the rolled article to improve the superconducting properties of the article. A superconducting article comprised of one or more elongated metal matrix regions containing one or more embedded elongated superconducting Mg—B regions running the full length of the article is disclosed, wherein the superconducting Mg—B regions have a density greater than 95 % of the theoretical density, and a transition temperature in zero field of 30 K.

Abstract: A multifilamentary superconducting composite article includes a plurality of oxide superconducting filaments in a ductile metal matrix arranged about a central core, and a region of high resistivity embedded within and adherent to the metal matrix and substantially surrounding each oxide superconducting filament. The high resistivity region is perforated and the perforation is occupied by a material having a bulk material resistivity greater than 0.4 &mgr;-cm. The article demonstrates a filament to filament resistance greater than 1×10−6 ohm-cm at T>Tc, where resistance is the four-point transport resistance between filaments multiplied by the measured sample length The ac power loss in a field perpendicular to the strand surface or in any other orientation is less than 2.5 mW/A-m at greater than 10 mT (RMS ac field, 30-300 Hz), as measured by magnetic methods without transport current. Methods of manufacture are provided.

Abstract: A multifilamentary superconducting composite article produces from a multifilament assembly which includes a plurality of oxide superconducting filaments in a ductile metal matrix arranged about a central core, the filaments generally having a trapezoidal cross-section. Methods of manufacture are provided.

Abstract: Processes for the fabrication of MgB2 powder and wires are provided. Powders are produced by mechanically alloying magnesium- and boron-containing precursors under controlled conditions to avoid secondary phase and impurity formation. Powders are also prepared by vapor phase reaction of volatile magnesium- and boron-containing precursors. Wires, tapes, films and coatings are provided.

Abstract: This invention relates to a practical superconducting conductor based upon biaxially textured high temperature superconducting coatings. In particular, methods for producing flexible and bend strain-resistant articles and articles produced in accordance therewith are described which provide improved current sharing, lower hysteretic losses under alternating current conditions, enhanced electrical and thermal stability and improved mechanical properties between otherwise isolated films in a coated high temperature superconducting (HTS) wire. Multilayered materials including operational material which is sensitive to bend strain can be constructed, in which the bend strain in the region in which such operational material is located is minimized. The invention also provides a means for splicing coated tape segments and for termination of coated tape stack ups or conductor elements.

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 defied 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 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)≧3.5×1010 exp(−32,000/T+273) and an upper bound defined by the equation, PO2(upper)≦1.1×1012 exp(−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: Oxide bronze compositions and articles manufactured in accordance therewith are provided. The oxide bronze compositions have the general formula AxBOy, in which A comprises an alkali, alkaline earth or rare earth metal and in which A has a valence, m, equal to 1, 2 or 3, B comprises a transition metal having a valence, n, less than or equal to 6,0<x<1 on an atomic ratio basis and y=[(x)(m)+n]/2. High temperature superconducting devices incorporating such compositions are also provided. The superconducting devices include a substrate having a polycrystalline superconducting layer or filament deposited on top of or embedded in the substrate. The superconducting layer or filament is formed of the oxide bronze composition. In some embodiments, the oxide bronze layer is textured with a full-width-half-maximum of a pole figure of less than or equal to 20 degrees.

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: A method of making an oxide superconductor article includes providing an oxide filament comprising a textured oxide superconductor precursor having an effective oxide flow stress, (&sgr;c, in a silver-based matrix, and converting the textured oxide superconductor precursor into an oxide superconductor. During precursor conversion, a compression stress is applied to the oxide filament which is greater than or equal to the oxide flow stress (&sgr;c), the silver-based matrix having a flow stress, &sgr;s, whereby &sgr;s>&sgr;c under conditions of phase conversion so that material flow between the silver-based matrix and the oxide filament is substantially avoided.

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 mixing raw powders with a desired ratio of Bi:Pb:Sr:Ca:Cu elements and reacting the mixture under different selected reaction conditions that form a precursor powder with a dominant (Bi, Pb)SCCO 2212 phase and without Ca—Pb—O phase, wherein the 2212 phase may be the orthorhombic 2212 phase. The precursor article is then subjected to optimized reaction and mechanical deformation processes that lead to a reaction induced texturing and deformation induced texturing, respectively. A heating process is used to convert the precursor powder to the 2223 phase and subsequent deformation and annealing processes may be used to form a substantially single phase, highly textured (Bi, Pb)SCCO 2223 superconductor with high Jc.

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: A multicomponent powder useful in the formation of BSCCO-2223 is provided comprised of orthorhombic BSCCO-2212 and alkaline earth cuprate, without formation of undesirable secondary phases such as alkaline earth bismuthates and alkaline earth plumbates. A method for the production of the multicomponent powder includes providing a mixture of raw materials comprising constituent metallic elements in a ratio corresponding to a superconducting BSCCO-2223 material and heating the mixture under conditions which form a dominant amount of the orthorhombic BSCCO phase and the alkaline earth cuprate phase while preventing formation of an undesirable secondary phase selected from the group of alkaline earth plumbates and alkaline earth bismuthates. A subsequent heating step converts the multicomponent powder into the BSCCO-2223 and subsequent deformation and annealing processes may be used to form a substantially single phase, highly textured (Bi,Pb)SCCO-2223 superconductor article.

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 low-aspect ratio multi-filament superconductor wire includes a plurality of oxide superconductor filaments arranged in an elongated wire structure. Each filament of the wire also has a low-aspect ratio. The filaments are textured such that a crystallographic c direction of each filament is aligned with a crystallographic c direction of all other filaments with the crystallographic c directions being perpendicular to the longitudinal axis of the wire structure. The invention also features a groove rolling machine for forming a low-aspect ratio multi-filament superconductor wire by texturing a precursor tape by deforming the tape to a low-aspect ratio wire by reducing a larger dimension of the tape in such a way as to prevent buckling of the tape. A superconducting cable can be formed by planetary winding a plurality of multi-filament superconductor wires.

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: An optical element for changeable traffic signs consisting of a light source, in particular, a light-emitting diode (LED), at least one converging lens and one diverging lens, which are arranged coaxially in a shared housing. The light exiting from the light source is captured as completely as possible by the converging lens, concentrated in a focal spot, which is preferably surrounded by a diaphragm and directed further onto the diverging lens which distributes it according to certain specifications. The refracting power of the diverging lens is dimensioned such that light exiting from it features a smaller angle of exit &bgr; than a prescribed limit angle &agr;. The distance between the converging lens and the diverging lens is dimensioned such that sunlight incident from the outside at an angle &ggr; greater than or equal to the limit angle &agr; is completely blocked, either by the diaphragm or by absorption on the housing wall, so that no phantom light is generated.