EP0362237A1 - Supraleitende materialien, verfahren und davon abgeleitete anordnungen - Google Patents

Supraleitende materialien, verfahren und davon abgeleitete anordnungen

Info

Publication number
EP0362237A1
EP0362237A1 EP88904251A EP88904251A EP0362237A1 EP 0362237 A1 EP0362237 A1 EP 0362237A1 EP 88904251 A EP88904251 A EP 88904251A EP 88904251 A EP88904251 A EP 88904251A EP 0362237 A1 EP0362237 A1 EP 0362237A1
Authority
EP
European Patent Office
Prior art keywords
superconductor
superconducting
oxygen
ionic conductor
oxide
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Withdrawn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
EP88904251A
Other languages
English (en)
French (fr)
Inventor
Jan Edgar Evetts
Derek John Fray
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.)
CAMBRIDGE ADVANCED MATERIALS LIMITED
Original Assignee
CAMBRIDGE ADVANCED MATERIALS 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
Priority claimed from GB878711479A external-priority patent/GB8711479D0/en
Application filed by CAMBRIDGE ADVANCED MATERIALS Ltd filed Critical CAMBRIDGE ADVANCED MATERIALS Ltd
Publication of EP0362237A1 publication Critical patent/EP0362237A1/de
Withdrawn legal-status Critical Current

Links

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
    • H10N60/20—Permanent superconducting devices
    • H10N60/203—Permanent superconducting devices comprising high-Tc ceramic materials
    • 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
    • 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
    • H10N60/0661—Processes performed after copper oxide formation, e.g. patterning

Definitions

  • This invention concerns superconducting materials and their manufacture and is directed to improvements in the design and fabrication of high critical temperature superconducting films, components and wires, whereby highly reactive or chemically unstable superconducting materials can be adjusted in a controlled way to their optimum composition and state of oxidation or valence state and subsequently stabilised and maintained in this optimum condition.
  • these materials are chemically extremely active, in particular exhibiting extreme sensitivity to the presence of oxygen and moisture, and in view of their extreme chemical activity, the components are also susceptible to corrosion and environmental degradation.
  • the present invention provides a superconductor in which the composition and valence state (and therefore the s perconductivity) of the superconducting material is adjusted and maintained by the electrochemical addition or subtraction of material, on the application of electrochemical potential, from or to a donor or receptor control material, located in close proximity thereto.
  • valence controlling material can be controlled very precisely using electrochemical techniques.
  • the addition or removal can be referred to as enhancement and the material transferred can be thought of as the enhancement material.
  • electrochemical techniques allows the chemical activities of chemical constituents of materials to be varied over a wide range. For example, it is possible to generate electrochemically, hydrogen activities equivalent to many tens of thousands of atmospheres of pressure in steel. A further advantage is that if a solid electrolyte is employed it is possible to create these pressures or activities completely in the solid state, without recourse to the gaseous or liquid environments.
  • superconductor as employed herein is intended to mean a material which is capable of superconductivity.
  • an ionic conductor such as an electrolyte is interposed between the superconductivity material and the donor or receptor material.
  • the superconducting material is an oxide
  • the ionic conductor is an electrolyte and oxygen is transported through the electrolyte from a a solid or liquid or gaseous source of oxygen.
  • the ionic conductor may cover certain external surfaces of the superconducting material or may fully encapsulate the superconducting material.
  • the ionic conductor may for example coat some or all of the outside of the wire.
  • the ionic conductor may coat the sides of a passage through 'or hollow channels, cavities or ducts contained within a component or wire.
  • the passages, channels, cavities or ducts may be filled with a solid enhancement material such as an oxide (where the enhancement material is to be oxygen) and if required, a conducting electrode.
  • a solid enhancement material such as an oxide (where the enhancement material is to be oxygen)
  • a conducting electrode if required, it is possible to control the oxygen partial pressure by exposing them to a mixture of metal and metal oxide. If, for example, it is found that the optimum superconductivity is at a partial pressure of 10 -13 atm, this could be achieved by heating the superconductor in a mixture of copper and cuprous oxide at
  • the level of enhancement be adjusted to an optimum value for the material, during fabrication and commissioning of the superconductor, and thereafter maintained at that level.
  • the superconductor can be maintained in its optimum state by control of the electrochemical potential in service or during maintenance of the material.
  • active feed back control of the enhancement or optimum composition of the material may be achieved in superconductors with a sufficiently high superconducting transition temperature.
  • the superconductivity of such materials may depend so critically on the composition or enhancement level that active control of this sort may be essential for practical applications, e.g. the control of oxygen concentration in the superconductor.
  • the ionic conductor may be separated from the superconductor by, a layer of material which is readily permeable by the atoms or ions of the enhancement material which are to combine with or be removed from the superconductor to establish -the superconducting phase - e.g. oxygen, atoms or ions.
  • the superconductor and the ionic conductor may be fabricated as one unit or joined after separate manufacture. Alternatively one component may be deposited or formed onto the other. Thus an oxide film may be deposited onto a substrate which comprises an ionic conductor.
  • the invention also provides a superconductor in which the superconductor material may consist of a compacted powder pellet that has been appropriately pretreated, reacted, graded and possibly magnetically separated prior to compaction, and an encapsulating ionic conductor which may be similarly fabricated from compacted powders, and may be formed and heat treated in conjunction with the first material.
  • the superconductor and the ionic conductor may be in intimate contact or separated by a thin deformable support or spacer, which at a later stage, is rendered oxygen permeable.
  • the support or spacer is preferably an electronic conductor.
  • the invention also envisages an alternative method of
  • the superconductor is formed first as * a metallic alloy and subsequently anodised or oxidised after fabrication to form an oxide superconductor.
  • the superconductor may surround the ionic conductor.
  • a central core may be formed from a conductive metal, surrounded by a source of or sink for enhancement material which itself is separated from a cylindrical layer of superconductor by an ionic conductor also in the form of a cylindrical layer.
  • the superconductor layer may be enclosed within a suitable covering material, to separate the superconductor from the environment.
  • a conductive element may be required at the interface between the covering and the superconductor if the former is not electrically conductive, and the covering may itself be coated, or otherwise covered or incorporate an electrically insulating material.
  • liquid electrolytes can also be used.
  • lithium is required to be inserted this could be achieved by using an aluminium-lithium anode and a liquid lithium ion conductor, either organic or inorganic,
  • the inorganic electrolyte could be molten lithium chloride at 900K.
  • a further possible addition would be to include bismuth oxide containing strontium oxide, calcium oxide or lanthanum oxide as examples of solid electrolytes which conduct oxygen ions.
  • Fig.l illustrates an oxygen ion conductor composite
  • Fig 2 illustrates the layers required in an example based on YBaCuO
  • Fig 3 is a cross section through a wire which is capable of functioning as a superconductor and which is stabilised in accordance with the invention
  • Fig 4a and 4b illustrate the layers required for controlling the oxygen and copper and fluorine levels in a superconducting composite
  • Fig 5 illustrates a pellet-sandwich arrangement by which oxygen or fluorine penetration can be measured.
  • An oxide 10 for example LaSrCuO or YBaCuO, is prepared in contact with a solid state ionic conductor 12 of oxygen ions such as calcia zirconia, or yttria zirconia or any other oxygen ion conductor. Both of these compounds are ionic conductors .
  • a source of oxygen 14 on the other side of the ionic conductor such as oxygen gas or a - 3 - metallic oxide, and by applying a potential, oxygen ions are transported through the ionic conductor from or to the oxide superconductor depending on the polarity, as shown.
  • the composite In order to prevent the oxygen escaping it may be necessary to coat the composite with an oxygen impermeable membrane such as a metal, e.g. Al or Au. If, however, it is necessary to maintain a very low oxygen partial pressure, the voltage and current can be applied in the reverse direction. For a voltage drop of 0.3V in the reverse direction the oxygen partial pressure would be i x
  • the composition of the intercalated oxide will not change. Using this technique, it is possible to stabilise the oxide phase and, secondly, to extend the range of oxygen activities or pressures far in excess of those hitherto investigated.
  • Cu 2+/Cu3+ or alkaline earth composition by utilising an appropriate ion conductor, e.g. a copper ion conductor or an alkaline earth conductor instead of an oxygen ion conductor.
  • an appropriate ion conductor e.g. a copper ion conductor or an alkaline earth conductor instead of an oxygen ion conductor.
  • fluorine may be introduced into materials using a fluorine ion conductor such as LaF- or any other fluorine ion conductor.
  • the invention envisages that the composition of super conductors, may be altered, maintained, and monitored using ionic conductors and appropriate electrical potentials.
  • a layer of YBaCuO 16 which is to form a superconductor is sputtered onto an oxygen ion conductor, substrate 18 for example yttria zirconia and then coated with gold at 20.
  • Oxygen either from the air or copper oxide is transferred electrochemically into the superconductor material.
  • the oxygen source is air, transfer occurs through a porous platinum electrode 22 on the underside of the substra-te, the platinum layer acting as an electronic conductor and a catalyst.
  • the oxygen source is copper oxide, the porous platinum layer is not required, the mixture acting as the conductor.
  • the oxygen activity can be measured after the end of the transfer or intercalation and, due to the fact that the system is sealed, phases and superconduction compositions may be created which are unstable under ambient conditions.
  • the oxygen transfer will most likely take place at temperatures above 673°K but with thin films of ionic conductor it may be possible to attain results at
  • a copper wire (24) is surrounded by. copper oxide (26), within a tube of oxygen ion conductor (28), e.g. yttria zirconia.
  • This is surrounded by an oxide superconductor (30) which is sheathed in copper (32) separated from the superconductor by a tantalum diffusion barrier (34). Passing a current from the outer copper sheath to the inner copper wire will ensure that oxygen atoms pass into the oxide superconductor.
  • potentials may be measured ' etc. as previously mentioned.
  • Figure 4a shows how the invention can enable both oxygen and copper concentrations to be controlled by use of two solid electrolytes, each one monitored and controlled independently, provided the central core is conductive.
  • a ceramic superconductor in the form of a yttria barium copper oxide layer 36 is sandwiched between an oxygen ionic conductor of yttria zirconia 38 and a copper ionic conductor layer 40 of copper beta aluminium.
  • a copper electrode 42 on the other surface, 40 provides copper ions/atoms and a copper/copper oxide oxygen ion/atom source 44 as provided below a porous platinum barrier film 46.
  • FIG. 4b Control of both oxygen and fluorine concentrations by use of two solid electrolytes is shown in Figure 4b.
  • an Yttria Barium Copper Oxide superconductor layer 48 is sandwiched between a lanthanum fluoride layer 50 forming a fluorine ion conductor, and a layer 52 of Yttria Zirconia 52, forming an oxygen ion conductor.
  • Porous platinum electrode layers 54 and 56 provide for the establishment of an electric potential through the junction and a source of fluorine ions/atoms and oxygen ions/atoms are provided beyond both electrodes.
  • Figure 5 shows an arrangement whereby further tests were made to determine the transfer of oxygen and fluorine into a superconductor.
  • Pellets of Cu,Cu 2 0, (58) yttria stabilised zirconia (60) and Y. Ba-Cu-O-, superconductor (62) were pressed together and heated to 750°C. On the application of 2.04V, a current of 15 mA cm flowed. This voltage includes the resistive and polarisation losses as well as the potential difference across the electrodes» After three hours titration it was found that the partial pressure of oxygen given by the superconductor was 1000 atm. The compressi e force was obtained from a spring (64) acting through a rod (66).
  • the invention allows the exact enhancement activity (eg oxygen activity in an oxide superconductivity material) to be monitored by measuring the potential between the superconducting material and the reference across the ionic conductor (electrolyte), without the need for chemical analysis. Connection to the level of activity may be made by eg adjusting the electrochemical potential.
  • exact enhancement activity eg oxygen activity in an oxide superconductivity material
  • Superconducting oxides are themselves very like ionic conductors and may be used in titration configurations without a separate ionic conductive layer, and the invention includes within its scope arrangements of such oxide superconductors in which the latter itself functions in part as an ionic conductor.
  • the invention lies in the control of the conductivity of a mixture of elements so as to produce superconductivity by electrochemically altering the valence state of one of the elements and causing at least one other element to migrate into or out of the mixture to re-establish the charge neutrality of the mixture.

Landscapes

  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Chemical & Material Sciences (AREA)
  • Ceramic Engineering (AREA)
  • Inorganic Compounds Of Heavy Metals (AREA)
  • Superconductors And Manufacturing Methods Therefor (AREA)
  • Compositions Of Oxide Ceramics (AREA)
EP88904251A 1987-05-15 1988-05-13 Supraleitende materialien, verfahren und davon abgeleitete anordnungen Withdrawn EP0362237A1 (de)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
GB878711479A GB8711479D0 (en) 1987-05-15 1987-05-15 Superconducting materials
GB8711479 1987-05-15
GB8714993 1987-06-26
GB878714993A GB8714993D0 (en) 1987-05-15 1987-06-26 Superconducting materials

Publications (1)

Publication Number Publication Date
EP0362237A1 true EP0362237A1 (de) 1990-04-11

Family

ID=26292245

Family Applications (1)

Application Number Title Priority Date Filing Date
EP88904251A Withdrawn EP0362237A1 (de) 1987-05-15 1988-05-13 Supraleitende materialien, verfahren und davon abgeleitete anordnungen

Country Status (5)

Country Link
EP (1) EP0362237A1 (de)
JP (1) JPH02503422A (de)
AU (1) AU614522B2 (de)
FI (1) FI895441A0 (de)
WO (1) WO1988009061A2 (de)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3736301A1 (de) * 1987-10-27 1989-05-11 Basf Ag Verfahren zum einstellen der sprungtemperatur von keramischen supraleitern
FR2626409B1 (fr) * 1988-01-22 1991-09-06 Thomson Csf Dispositif en materiau supraconducteur et procede de realisation
EP0429456A1 (de) * 1988-03-30 1991-06-05 Elmwood Sensors Limited Elektrisch leitfähige keramik, verfahren zu dessen herstellung und leiter daraus
DE102010026098A1 (de) * 2010-07-05 2012-01-05 Forschungszentrum Jülich GmbH Ionisch gesteuertes Dreitorbauelement

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
BE636119A (de) * 1962-08-27
JPS5137667B2 (de) * 1971-11-13 1976-10-16
FR2529384B1 (fr) * 1982-06-25 1986-04-11 Thomson Csf Procede de reduction de compose en couche sur un substrat et son application a la fabrication de structure semi-conductrice a effet de champ
FR2542500B1 (fr) * 1983-03-11 1986-08-29 Thomson Csf Procede de fabrication d'un dispositif semiconducteur du type comprenant au moins une couche de silicium deposee sur un substrat isolant

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO8809061A2 *

Also Published As

Publication number Publication date
FI895441A0 (fi) 1989-11-15
AU614522B2 (en) 1991-09-05
JPH02503422A (ja) 1990-10-18
WO1988009061A3 (en) 1988-12-01
WO1988009061A2 (en) 1988-11-17
AU1720388A (en) 1988-12-06

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