EP0914680A2 - Couches intermediaires metallisees pour supraconducteurs au cuprates a temperature de transition elevee - Google Patents

Couches intermediaires metallisees pour supraconducteurs au cuprates a temperature de transition elevee

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Publication number
EP0914680A2
EP0914680A2 EP97924405A EP97924405A EP0914680A2 EP 0914680 A2 EP0914680 A2 EP 0914680A2 EP 97924405 A EP97924405 A EP 97924405A EP 97924405 A EP97924405 A EP 97924405A EP 0914680 A2 EP0914680 A2 EP 0914680A2
Authority
EP
European Patent Office
Prior art keywords
htsc
layers
partially substituted
rare earth
earth element
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP97924405A
Other languages
German (de)
English (en)
Inventor
Jeffery Lewis Tallon
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Industrial Research Ltd
Original Assignee
Industrial Research Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Industrial Research Ltd filed Critical Industrial Research Ltd
Publication of EP0914680A2 publication Critical patent/EP0914680A2/fr
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Classifications

    • 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 invention comprises a method for preparing HTSC materials having high critical current.
  • HTSC superconducting cuprates
  • T r values may be of the order of 93 K for example for YBa ⁇ Cu 3 0 7 i , 95K for example for Bi 2 SR 2 CaCu 2 0 8 , 109 K for example for Bi 2 Sr 2 Ca,,Cu.,0
  • T r values alone do not guarantee the utility of these HTSC at 77K or high temperatures Often these applications require large critical currents in the HTSC in the presence of a magnetic field.
  • H* is proportional to exp (d/C) the proportionality being dependent upon the hole concentration and upon a universal function f(T/T c ).
  • the invention comprises a method of preparing a high temperature superconducting cuprate material (HTSC) having a crystalline structure comprising intrinsically superconducting Cu0 2 layers and non-superconducting intermediate layers between the superconducting layers in the crystalline structure of the material, comprising preparing the material such that at least one intermediate layer between the CuO a layers is conductive whereby superconductivity can be induced in the intermediate layer(s) between the superconducting layers by proximity effect to thereby increase the critical current of the material.
  • HTSC high temperature superconducting cuprate material
  • the method includes causing the intermediate layer(s) to become conductive by introducing sufficient oxygen into the intermediate layer(s) during preparation of the HTSC material.
  • the HTSC may be a Bi-Sr-Ca-Cu-O based HTSC and said intermediate layers comprise Bi-O layers.
  • the HTSC may be of nominal composition B ⁇ 2 Sr 2 CaCu 2 O s where Bi may be partially substituted by Pb, Hg, Re, Os, Ru. Tl. V. Cr. Zr, Nb. Mo, Hf, Ta. W, Co, or Sm, Sr may be partially substituted by Ba or a larger lanthanide rare earth element, and Ca may be partially substituted by Y or a lanthanide rare earth element.
  • the HTSC may be of nominal composition B ⁇ 2 Sr 2 Ca 2 Cu 3 O[ 0 , where Bi may be partially substituted by Pb, Hg, Re, Os, Ru, Tl. V, Cr, Zr, Nb, Mo, Hf, Ta, W, Co, or Sm, and Sr may be partially substituted by Ba or a larger lanthanide rare earth element, and Ca may be partially substituted by Y or a lanthanide rare earth element.
  • the HTSC may be a Tl-Sr-Ca-Cu-O based HTSC and said intermediate layers comprise Tl-O layers.
  • the HTSC may be an Hg-Ba-Ca-Cu-0 based HTSC and said intermediate layers comprise Hg layers.
  • the effective interlayer spacing d referred to above us reduced and H* is thereby increased.
  • the method of the invention may be described as metallising one or more of the non-Cu0 2 layers between groups of Cu0 2 layers.
  • the Cu0 2 layers which intrinsically superconduct, induce superconductivity in the metallic intermediate layer(s) by proximity effect and then the d, spacing is not the spacing between the Cu0 2 layers but the smaller spacing between a Cu0 2 layer and the intermediate layer. If the intermediate layer lies halfway between the Cu0 2 layers then the d, spacing is halved and H* may increase 10 fold.
  • Figure IA is a diagram of the structure of the bismuth oxide layer of B ⁇ 2 Sr 2 CaCu 2 O s , A showing the pseudo-perovskite strip of structure running through the general background rocksalt structure, Figure IB shows additional oxygen loaded into the pseudo-perovskite strip to provide a direction connectivity of the strip, and Figure 1C shows the ideal structure for B ⁇ 2 Sr 2 CaCu 2 O ⁇ +4 where a single additional oxygen atom is added to each BiO layer to convert the layer from rocksalt to perovskite and thus reduce the Bi-O bondlength;
  • Figure 2 is a diagram showing T c plotted against the muon spin depolarisation rate of ⁇ (o) for several HTSC materials showing the typical loop followed by most HTSC and the plateau for Y-123 and Hg, Re- 1212 due to the enhanced superfluid density occurring within metallised interlayers;
  • Bi-Sr-Ca-Cu-O (BSCCO) based HTSC is characterised by perovskite packing of the Ca-Cu0 2 -SrO layers and rocksalt packing of the B1O-B1O layers.
  • the stacking of interlayers between CuO,. layers follows the sequence: CuO z - SrO-B ⁇ O-B ⁇ O-SrO-Cu0 2 so that adding additional oxygen to or metallising the BiO layer substantially reduces the d, spacing.
  • the in-plane separation of a pair of Bi atoms is 0.54nm and if the linking oxygen atom were to reside in the mid-pomt position the in- plane BiO bond length would be 0.27nm.
  • substantially the entire bismuth oxide layer is converted to perovskite packing so that the Bi-O bondlength is between 0.19 and 0.22nm, and typically between 0.19 to 0.20nm as shown in Figure 1 C.
  • This is accomplished by adding nearly one oxygen atom per formula unit to the BiO layer such that it becomes a Bi0 2 layer and the formulae become Bi 2 Sr 2 CaCu 2 0 1(W A or B ⁇ 2 Sr 2 Ca 2 Cu 3 0 12tA , in both cases where -0.2 ⁇ ⁇ ⁇ +0.2.
  • additional oxygen is introduced by annealing the material in an oxygen containing atmosphere. This may take place when forming long-length flexible wires or tapes by the technique known m the art as powder-in-tube processing.
  • Powders of these materials or precursors to these materials are packed into a metallic tube, often made of silver metal or silver alloy, and then by a process of deformation and heat treatment the tube is drawn out into a long wire and oxide reacted to form a highly-textured HTSC core.
  • Oxygen may also be added to electrochemically loading oxygen. Oxygen may be introduced by substituting a higher valence cation for a lower valance cation. A combination of any of the above may be used.
  • BSCCO compounds the stacking of interlayers between Cu0 2 , layers follows the sequence: Cu0 2 -SrO-B ⁇ O-B ⁇ O-SrO-Cu0 2 so that adding additional oxygen to, or metallising the BiO layer, substantially reduces the d, spacing.
  • additional oxygen may be introduced in the BiO layer by substituting a higher valence atom for Bi such as Pb, Hg, Re, Os, Ru, Tl, V, Cr, Zr, Nb, Mo, Hf, Ta. W, Co or Sm.
  • the bond length may be lengthened to greater than 0.20 but less than 0.22 by further substituting sufficient Ba for Sr.
  • the BiO bond length may also be reduced by increasing the substitution level of Pb because Pb 2+ is a larger ion than is B ⁇ 1 ⁇ .
  • the BiO bond length may be shortened by substituting Hg ⁇ for Bi J+ .
  • Tl-Sr-Ca-Cu-O compounds the stacking of interlayers between Cu0 2 , layers follows the sequence: Cu0 2 -BaO-T10-BaO-Cu0 2 so that adding additional oxygen to, or metallising the TIO layer, substantially reduces the d, spacing
  • the HTSC may be of nominal composition TIBa z Ca. ,Cu n 0 2n f 1 or ,Cu_0 2n - Struktur where Tl may be partially substituted by Bi, Pb or Hg, Ba may be partially or wholly substituted by Sr, and Ca may be partially substituted by Y or any larger lanthanide rare earth element.
  • a preferred compound is Tl 05 Pb 05 Sr 2 Ca 2 Cu n O 2- ⁇ i .
  • Hg-Ba-Ca-Cu-O compounds the stacking of interlayers between Cu0 2 layers follows the sequence: Cu0 2 -BaO-Hg-BaO-Cu0 2 so that adding additional oxygen to or metallising the Hg layer substantially reduces the d, spacing.
  • Pb, Tl, Sr, Re, Os, Ru, Tl, V, Cr, Zr, Nb, Mo, Hf, Ta, W, Co, or Sn, and Ba may be partially or wholly substituted by Y or a larger lanthanide rare earth element, and Ca may be partially substituted by Y or any lanthanide rare earth element.
  • Preferred compounds are those in which 25% of the Hg atoms are substituted by Re such that the Hg layer becomes an Hg o 75 Re 025 0 layer which is metallic.
  • Polycrystalhne samples of YBa 2 Cu 3 0 78 (Y-123) were synthesized using standard techniques from oxide precursors. These were annealed at different temperatures and oxygen partial pressures in order to provide a series of samples with different ⁇ values which were then quenched in order to freeze m the oxygen content.
  • the muon spin depolarisation rate, ⁇ (O) was determined for each of the samples and is plotted in Figure 2 in the form of T c plotted against ⁇ (O).
  • ⁇ (O) is a measure of the superfluid density.
  • Y-123 and the related compound Y 2 Ba 4 Cu 7 0 15 . 4 (Y-247) can be seen to have very high values of H* in comparison with other materials.
  • the Ca substitution overdopes the sample so in order to achieve optimal doping some oxygen must be removed from the chains.
  • ⁇ 0.39 and the chains are so oxygen deficient that the metalhcity of the chains is destroyed and induced superconductivity on the chains is suppressed.
  • H* is reduced by nearly a factor of 10 and the data point is plotted in Figure 4 as Ca-123.
  • the effective d, spacing can now be seen to be the full plane-to-plane distance as superconductivity on the chains is destroyed. Similar results are obtained when the chains are oxygen depleted then brominateri.
  • the sample is optimally doped but the chains are not metallic or superconducting and the data point annotated Br-123 shows also that the effective d, spacing is the plane-to-plane distance.
  • thermoelectric power values 5.33 ⁇ V/K and 0.49 ⁇ V/K, respectively, the last value indicating a slightly overdoped sample.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Ceramic Engineering (AREA)
  • Inorganic Compounds Of Heavy Metals (AREA)
  • Compositions Of Oxide Ceramics (AREA)
  • Superconductors And Manufacturing Methods Therefor (AREA)

Abstract

Un procédé de préparation d'un cuprate supraconducteur à haute température (HTSC), permettant d'avoir un courant critique accru, consiste à métalliser des couches intermédiaires non supraconductrices entre les couches supraconductrices dans la structure cristalline du matériau, de manière à induire une supraconductivité dans la ou les couches intermédiaires dans les couches supraconductrices par effet de proximité. On ajoute typiquement de l'oxygène dans les couches intermédiaires, pendant la préparation du matériau HTSC, telles que les couches Bi-O dans des matériaux Bi-Sr-Ca-Cu-O, les couches TlO dans des matériaux Tl-Sr-Ca-Cu-O, et la couche Hg dans des matériaux Hg-Ba-Ca-Cu-O.
EP97924405A 1996-06-07 1997-06-09 Couches intermediaires metallisees pour supraconducteurs au cuprates a temperature de transition elevee Withdrawn EP0914680A2 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
NZ28676696 1996-06-07
NZ28676696 1996-06-07
PCT/NZ1997/000075 WO1997049118A2 (fr) 1996-06-07 1997-06-09 Couches intermediaires metallisees pour supraconducteurs au cuprates a temperature de transition elevee

Publications (1)

Publication Number Publication Date
EP0914680A2 true EP0914680A2 (fr) 1999-05-12

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EP97924405A Withdrawn EP0914680A2 (fr) 1996-06-07 1997-06-09 Couches intermediaires metallisees pour supraconducteurs au cuprates a temperature de transition elevee

Country Status (3)

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EP (1) EP0914680A2 (fr)
AU (1) AU2983197A (fr)
WO (1) WO1997049118A2 (fr)

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Publication number Priority date Publication date Assignee Title
DE602004010816T2 (de) * 2004-10-19 2008-12-24 Nexans Verbessertes Hochtemperatur-Supraleiter Material des BSCCO Systems

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO9749118A3 *

Also Published As

Publication number Publication date
WO1997049118A2 (fr) 1997-12-24
WO1997049118A3 (fr) 1998-02-26
AU2983197A (en) 1998-01-07

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