EP0400057A4 - Preparation of superconducting oxides by electrochemical oxidation: anodic superconductors - Google Patents

Preparation of superconducting oxides by electrochemical oxidation: anodic superconductors

Info

Publication number
EP0400057A4
EP0400057A4 EP19890902671 EP89902671A EP0400057A4 EP 0400057 A4 EP0400057 A4 EP 0400057A4 EP 19890902671 EP19890902671 EP 19890902671 EP 89902671 A EP89902671 A EP 89902671A EP 0400057 A4 EP0400057 A4 EP 0400057A4
Authority
EP
European Patent Office
Prior art keywords
anode
superconducting oxide
alloy
superconducting
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Withdrawn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
EP19890902671
Other languages
English (en)
Other versions
EP0400057A1 (de
Inventor
Ronald M. Latanision
Peter C. Searson
Pradnya V. Nagarkar
Thomas P. Moffat
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.)
Massachusetts Institute of Technology
Original Assignee
Massachusetts Institute of Technology
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 Massachusetts Institute of Technology filed Critical Massachusetts Institute of Technology
Publication of EP0400057A1 publication Critical patent/EP0400057A1/de
Publication of EP0400057A4 publication Critical patent/EP0400057A4/en
Withdrawn legal-status Critical Current

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D11/00—Electrolytic coating by surface reaction, i.e. forming conversion layers
    • C25D11/02—Anodisation
    • C25D11/34—Anodisation of metals or alloys not provided for in groups C25D11/04 - C25D11/32
    • 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

Definitions

  • This invention relates to superconducting materials.
  • Superconductors are materials having zero resistance to the flow of electrons below a certain critical temperature, T c . It is known that certain metal oxides, e.g., La 2-x Ba x CuO 4-y , La 2-x Sr x CuO 4-y , Ba 2 YCu 2 O 9-Y , etc. exhibit superconductivity. It is desirable to provide such oxides in forms, e.g., wires or thin films, that permit practical utilization of their superconductive property.
  • the invention features preparing a superconducting oxide by electrochemical oxidation.
  • an electrochemical cell containing an anode made of an alloy of the metallic precursors of the superconducting oxide is provided.
  • a surface of the anode is in contact with the electrolyte of the cell, and the anode is electrochemically oxidized to form the superconducting oxide.
  • the metallic precursors are present in the alloy in the stoicherr.etric proportions of the metals in the oxide.
  • the metallic precursors are La, M, and Cu and the superconducting oxide has the formula La 2-y M x CuO 4-y .
  • M is an alkaline earth element such as Ba, Sr, or Ca.
  • the metallic precursors are rare earth elements (N), Ba, and Cu and the superconducting oxide has the formula NBa 2 Cu 3 O 7-y .
  • rare earth elements are Y, La, Eu, Gd, Tb, Dy, Hu, Er, Tm, Yb, or Lu.
  • the alloy is formed using rapid solidification techniques to provide a homogeneous alloy.
  • Formation of superconducting oxides by electrochemical oxidation allows considerable control over the structure, composition, and thickness of the oxide through adjustment of oxidation conditions, e.g., electrolyte composition, temperature, applied voltage or current and duration of oxidation.
  • oxidation conditions e.g., electrolyte composition, temperature, applied voltage or current and duration of oxidation.
  • the thickness of the superconducting oxide layer formed can be controlled by electrochemically oxidizing until the desired thickness is obtained.
  • the Figure is an electrochemical cell.
  • an electrochemical cell 10 includes a container 12, an anode 14, a reference electrode 16, a counter electrode 17, a power supply 18, and an electrolyte 20.
  • the container 12 is made of an inert material, such as glass.
  • the anode 14 is made of an alloy of the precursor metals of the superconducting oxide.
  • the precursor metals are present in the stoichiometric proportions of the metals in the target oxide.
  • the alloy is homogeneous, i.e., the chemical composition and microstructure of the alley is substantially uniform throughout. Homogeneity is achieved by using standard rapid solidification techniques such as melt spinning or inert gas atomization.
  • the surface of the anode should be smooth to achieve a reproducible surface condition; the smoothness can be generated through conventional abrasion or polishing (e.g., electropolishing) methods.
  • the alloy may also be degassed in a suitable inert solvent, e.g., cyclohexane.
  • the reference electrode 16 provides a reference potential for the applied voltage (or current) used to form the oxide.
  • the preferred reference electrode is a high impedence glass electrode such as a saturated calomel electrode.
  • the counter electrode completes the electrochemical circuit and allows electric current to pass between itself and the anode.
  • Suitable counter electrodes include standard platinum and graphite electrodes.
  • the power supply 18 provides a constant voltage to the cell during the oxidation. Where the oxidation is by galvanostatic techniques, a constant current supply is used. Current and voltage metering instruments are incorporated into the power source configuration.
  • the electrolyte 20, in which the electrodes are immersed may be aqueous, non-aqueous, or a molten salt, depending upon the alloy composition and desired film characteristics.
  • Non-aqueous electrolytes are most preferred.
  • suitable aqueous electrolytes include sulphuric acid and sodium hydroxide solutions.
  • non-aqueous electrolytes which should be used where oxide formation in the absence of water is desired, includes solvents such as ethanol, ammonia, and acetonitrile.
  • the ionic strength of the electrolyte can be increa-rrd by the addition of, e.g., hydrochloric acid.
  • molten salt electrolytes are LiCl and Na 2 SO 4 .
  • the oxidations events are carried out using standard methods well known to those skilled in the art.
  • the potential is kept constant (perferably between 2.5 V and -2.5 V, with respect to the reference electrode), and the current passed by the anode is monitored to follow the rate of oxide formation.
  • the current is kept constant (preferably between 10 -1 A and 10 -6 A/cm 2 ) and the anode potential is monitored to follow the rate of oxide formation.
  • the cell can also contain a means for temperature control of the electrolyte and a means for regulating the gas content of the eiectrolyte.
  • the oxidation can be performed with an open circuit, thereby making a counter electrode unnecessary.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Manufacturing & Machinery (AREA)
  • Inorganic Compounds Of Heavy Metals (AREA)
EP19890902671 1988-01-28 1989-01-25 Preparation of superconducting oxides by electrochemical oxidation: anodic superconductors Withdrawn EP0400057A4 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US14962188A 1988-01-28 1988-01-28
US149621 1988-01-28

Publications (2)

Publication Number Publication Date
EP0400057A1 EP0400057A1 (de) 1990-12-05
EP0400057A4 true EP0400057A4 (en) 1990-12-19

Family

ID=22531132

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19890902671 Withdrawn EP0400057A4 (en) 1988-01-28 1989-01-25 Preparation of superconducting oxides by electrochemical oxidation: anodic superconductors

Country Status (3)

Country Link
EP (1) EP0400057A4 (de)
JP (1) JPH03503548A (de)
WO (1) WO1989007161A1 (de)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2655356B1 (fr) * 1989-12-01 1992-04-30 Rhone Poulenc Chimie Procede de traitement electrochimique d'un materiau sous forme oxyde, application aux supraconducteurs et supraconducteurs ainsi obtenus.
FR2665713A2 (fr) * 1989-12-01 1992-02-14 Rhone Poulenc Chimie Procede de traitement par voie electrochimique d'un materiau sous forme d'oxyde.

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS63291318A (ja) * 1987-05-23 1988-11-29 Fujikura Ltd 酸化物系超電導線の製造方法

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
DATABASE WPIL. accession no. 89-013478, Derwent Publications Ltd, London, GB; & JP-A-63 291 318 (KUJIKURA CABLE WORKS K.K.) 29-11-1988 *

Also Published As

Publication number Publication date
WO1989007161A1 (en) 1989-08-10
EP0400057A1 (de) 1990-12-05
JPH03503548A (ja) 1991-08-08

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Inventor name: MOFFAT, THOMAS, P.

Inventor name: LATANISION, RONALD, M.

Inventor name: NAGARKAR, PRADNYA, V.

Inventor name: SEARSON, PETER, C.

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