Classifications

• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
  • C04B35/45—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on copper oxide or solid solutions thereof with other oxides
  • C04B35/4504—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on copper oxide or solid solutions thereof with other oxides containing rare earth oxides
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/622—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/64—Burning or sintering processes
  • C04B35/65—Reaction sintering of free metal- or free silicon-containing compositions
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
  • C23C8/06—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases
  • C23C8/08—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases only one element being applied
  • C23C8/10—Oxidising
• • C—CHEMISTRY; METALLURGY
  • C30—CRYSTAL GROWTH
  • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
  • C30B19/00—Liquid-phase epitaxial-layer growth
• • C—CHEMISTRY; METALLURGY
  • C30—CRYSTAL GROWTH
  • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
  • C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
  • C30B29/10—Inorganic compounds or compositions
  • C30B29/16—Oxides
  • C30B29/22—Complex oxides
• • C—CHEMISTRY; METALLURGY
  • C30—CRYSTAL GROWTH
  • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
  • C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
  • C30B29/10—Inorganic compounds or compositions
  • C30B29/16—Oxides
  • C30B29/22—Complex oxides
  • C30B29/225—Complex oxides based on rare earth copper oxides, e.g. high T-superconductors
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10N60/00—Superconducting devices
  • H10N60/01—Manufacture or treatment
  • H10N60/0268—Manufacture or treatment of devices comprising copper oxide
  • H10N60/0296—Processes for depositing or forming copper oxide superconductor layers
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10N60/00—Superconducting devices
  • H10N60/01—Manufacture or treatment
  • H10N60/0268—Manufacture or treatment of devices comprising copper oxide
  • H10N60/0801—Manufacture or treatment of filaments or composite wires
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10N60/00—Superconducting devices
  • H10N60/80—Constructional details
  • H10N60/85—Superconducting active materials
  • H10N60/855—Ceramic superconductors
  • H10N60/857—Ceramic superconductors comprising copper oxide

Definitions

• the present invention relates generally to superconducting compounds and methods of preparing the superconducting compounds. More particularly, the invention relates to preparation of superconducting ceramic materials having extremely high critical temperatures with the materials being prepared from metallic alloys having initial predetermined base geometries which are subjected to oxidation reactions to produce selected superconducting device geometries.
• T c critical temperatures
• a method for preparing a selected device geometry of a superconducting compound by beginning with a starting metal composition, constructing or forming a predetermined base geometry of the starting metal composition and subjecting the starting metal composition to a chemically generic oxidation reaction, such as reacting the starting metal composition with selected chalcogenides or halogens in order to produce the superconducting compound in the selected device geometry as derived from the predetermined base geometry.
• the method involves constructing a base metal structure, such as a copper block with channels, for receiving the starting metal composition and then subjecting the starting metal composition to a generic oxidation reaction to generate the superconducting compound in the selected device geometry, such as the copper block with a set of channels filled with superconducting compound.
• FIGURE 1 is a wire having a starting metal composition in the core region and an outer layer of a superconducting compound
• FIGURE 2 is a wire having a base metal core with an outer layer of superconducting compound
• FIGURE 3 illustrates two methods of assembling a starting metal composition with a base metal structure which receives the starting metal composition, (a) placing a bar of starting metal composition into open channels of the base metal structure and (b) pouring molten starting metal composition into partially closed channels of the base metal structure;
• FIGURE 4 is a base metal container for receiving a molten starting metal composition to be oxidized while in the molten state;
• FIGURE 5 is a base metal block and a thin overlayer of starting metal composition
• FIGURE 6 is a molten bath of starting metal composition for coating a wire of base metal which is passed through the molten metal bath;
• FIGURE 7 illustrates a furnace and coupled gas source for use in a batch processing mode of subjecting a starting metal composition to an oxidation reaction to generate a superconducting compound.
• the superconducting compound 12 generally has the chemical formula MX where M is at least one metal and X is an appropriate component for forming the superconducting compound
• the superconducting compound 12 has the chemical formula MNX where M is a metal selected from the group consisting essentially of the lanthanide rare earths or the group III B metals (such as-Y-and Sc), N is a metal selected from the group consisting essentially of the alkaline earth or alkali elements and X is a complex selected from the group consisting of a 3d, 4d, or 5d metal combined with chalogenide elements, such as
• the method of preparing the selected device geometry 10 of the superconducting compound 12 involves: (a) preparing a starting metal composition
• FIG. 2A One example of preparing the superconducting compound 12 is shown in FIG. 2A where the starting metal composition 14 is fabricated as an outer wire layer 17 surrounding a base metal core 18, such as copper or aluminum. It is this outer wire layer 17 having the starting metal composition 14 which forms one example of the predetermined base geometry 16.
• the wire layer 17 is then subjected to a chemically generic oxidation reaction (metal atoms reacting to reach a more positive valence, hereinafter referred to as, "oxidation reaction").
• this oxidation reaction is carried out by heating a coil of processed wire (not shown) in a furnace 20 having a coupled gas tank 22 (see FIG. 7).
• This system shown in FIG. 7 provides a controlled temperature and a gas atmosphere preferably of oxygen, or another chalcogenide, which enables formation of the superconducting compound 12.
• appropriate oxidation components such as CO 2 , SO 2 ,
• H 2 S, Cl 2 and F 2 can also be used to form the desired superconducting compound 12.
• the starting metal composition 14 is preferably a combination of a lanthanide, an alkaline earth and copper or a group III B metal, such as Y or Sc, an alkaline earth metal and copper.
• the composition 14 can be, (a) La 2-x M x Cu with M being Sr and/or Ba substituted for some of the La, or (b) Y x M y Cu z with M, for example, being Ba.
• These starting metal compositions 14 are then oxidized to produce the preferred crystal structures composed of La -x M x CuO 4 (see the Examples ) or YBa 2 Cu 3 O 7- ⁇ where ⁇ is about 0.1 to 0.3.
• the starting metal composition 14 is first prepared in the predetermined base geometry 16. Any typical metallurgical fabrication technology can be used, such as, casting, rolling and powder sintering. As discussed hereinbefore, FIG. 2A illustrates one embodiment wherein the starting metal composition 14 has the predetermined base geometry 16 of the outer wire layer 17 over the base metal core 18. The selected device geometry 10 is then achieved by subjecting the predetermined base geometry 16 to the oxidation reaction. As depicted in FIG. 2B, the selected device geometry 10 includes the outer wire layer 17 of the superconducting compound 12, an intervening layer of the starting metal composition 14 and the base metal core 18.
• FIG. 1A is another embodiment wherein the entire wire has the starting metal composition 14 and is the predetermined base geometry 16.
• the selected device geometry 10 is therefore readily achieved by carrying out the oxidation reaction to obtain the desired overlayer 23 of the superconducting compound (see
• FIG. 1B The first figure.
• FIG. 3 two additional embodiments:
• a bar or wire 24 having the starting metal composition 14 is in position for placement in a base metal block 26, such as copper.
• the bar 24 Prior to carrying out the oxidation reaction, the bar 24 is electrically connected (such as by brazing or cold welding) to the block 26 to form the predetermined base geometry 16.
• the selected device geometry 10 is then achieved by performing the oxidation reaction under conditions resulting in preferential oxidation of the bar 24.
• the starting metal composition 14 is molten and is poured into a reservoir 28. While the starting metal composition 14 is still in the molten state, the oxidation reaction is carried out.
• the starting metal composition 14 is rapidly transformed and forms a solid form of the superconducting compound 12. Once the melt completely oxidizes the desired superconducting compound 12 solidifies in the block 26 in the selected device geometry 10.
• the electrical connection between the superconducting compound 12 and the block 26 is achieved by diffusion of atomic components into the solid block
• This diffusion occurs most rapidly while the block 26 contains the molten starting metal composition 14 and superconducting compound 12 is at a high temperature in the solid form.
• This diffusion of atoms results in formation in the selected device geometry 10 of an intervening layer between the composition of the block 26 and the composition of the superconducting compound 12.
• Such an intervening transitional layer not only provides an electrical connection, but also provides a thermal expansion coefficient intermediate between that of the superconducting compound 12 and the block 26. This intermediate thermal expansion coefficient can prevent separation or spallation of the superconducting compound 12 from the block 26 which could arise from too large a difference of thermal expansion coefficient between the two materials.
• This intervening layer generated by diffusion of atoms can also be created for the first embodiment of FIG. 3 by means of a suitable heat treatment which is either separate from, or part of, the oxidation reaction.
• the block 26 is joined with a cover block (not shown) of the same base metal composition.
• This cover block can be joined to the block 26 by a swaging operation in which exposed flat ends 29 of the block 26 are joined to the cover block. This final assembly partially isolates the superconducting compound 12.
• FIG. 4 A variation on the second embodiment of FIG. 3 is illustrated in FIG. 4.
• the starting metal composition 14 is in molten form and is poured into a base metal structure 30.
• the volumetric expansion associated with the oxidation reaction of the starting metal composition 14 ensures good thermal and electrical contact between the resultant superconducting compound
• FIG. 5 is illustrated another embodiment wherein the starting metal composition 14 is deposited in a film layer 32 on a base metal substrate 34.
• the film layer 32 can be deposited in a conventional manner, such as by vapor deposition, sputtering, electroplating, cladding, plasma spraying or by simply dipping the substrate 34 in a molten bath of the starting metal composition 14.
• the film layer 32 of FIG. 5 can be formed in a stepwise manner with a series of layers of different chemical composition being formed. The first of these layers adjacent to the base metal substrate 34 is formed to insure strong adhesion, such as by epitaxial growth. Succeeding layers are varied in composition in order to provide a compositionally graded metal layer culminating in a metal region which yields the superconducting compound 12 after the oxidation reaction.
• FIG. 6 is shown another method of preparing the predetermined base geometry 16 of the starting metal composition 14.
• a feed wire 36 composed of a base metal, such as copper, is passed through a molten bath of the starting metal composition 14 which coats the feed wire 36 to form the predetermined base geometry 16.
• This wire form of the geometry 16 can then be transferred to another location and be subjected to the oxidation reaction as part of a continuous process to produce the selected device geometry 10.
• the following examples are merely illustrative and are not intended to limit the scope of the invention.
• Example I Appropriate molar quantities of Cu, La and Sr were melted together in a molybdenum crucible under a helium atmosphere to form an alloy of compositions 62 at. % La, 5 at. % Sr and 33 at. % Cu, which is the metallic starting composition corresponding to a preferred pervoskite oxide: La 1.85 Sr 0.15 CuO 4 . Droplets of the melt were quenched on a chill plate to inhibit phase separation. The alloy formed by this process was heated in air with the temperature raised slowly over a 24 hour period to 800°C and then air cooled. A La 2-x Sr x CuO 4 type pervoskite layer was produced as verified by x-ray diffraction analysis.
• Example II In this example appropriate molar quantities of 5 at. % La and 0.5 at. % Sr were added to copper shot in a molybdenum crucible and brought to a melting temperature of about 970oC. This liquid was poured into a boron nitride crucible and subsequently remelted. The resulting ingot was removed from the boron nitride crucible and sectioned into 2 micrometer thick wafers. Some of the wafers were exposed to air at 800°C for various time periods ranging from 10 minutes to 18 hours. Samples exposed to air for 10 minutes were examined with back scattering electron imaging and x-ray diffraction analysis, and these technique detected an 80 micrometer thick perovskite oxide layer attached to the Cu alloy. For samples oxidized for longer periods of time, a layer thickness greater than 200 micrometers tends to separate from the metal base layer.

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• 1988
  • 1988-03-21 WO PCT/US1988/000892 patent/WO1988008338A1/en not_active Ceased
  • 1988-03-21 AU AU19525/88A patent/AU1952588A/en not_active Abandoned
  • 1988-03-21 EP EP19880905473 patent/EP0312593A4/de not_active Withdrawn
  • 1988-03-21 JP JP63505126A patent/JPH01502977A/ja active Pending

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