[go: up one dir, main page]

WO1991015436A1 - A method of manufacturing superconducting ceramics - Google Patents

A method of manufacturing superconducting ceramics Download PDF

Info

Publication number
WO1991015436A1
WO1991015436A1 PCT/EP1991/000574 EP9100574W WO9115436A1 WO 1991015436 A1 WO1991015436 A1 WO 1991015436A1 EP 9100574 W EP9100574 W EP 9100574W WO 9115436 A1 WO9115436 A1 WO 9115436A1
Authority
WO
WIPO (PCT)
Prior art keywords
thallium
alloy
precursor
precursor alloy
tlba
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.)
Ceased
Application number
PCT/EP1991/000574
Other languages
French (fr)
Inventor
Jean-Louis Jorda
Michel Couach
Marie-Thérèse Cohen-Adad
Robert Abraham
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.)
Moltech Invent SA
Original Assignee
Moltech Invent SA
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 Moltech Invent SA filed Critical Moltech Invent SA
Publication of WO1991015436A1 publication Critical patent/WO1991015436A1/en
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

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
    • C04B35/622—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
    • 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
    • C04B35/4512—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 thallium 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
    • H10N60/0772—Processes including the use of non-gaseous precursors

Definitions

  • the invention relates to methods of manufacturing thallium-based cuprate superconducting ceramics .
  • Superconducting thallium compounds are amongst the most promising known superconducting materials from the point of view of the critical temperatures achieved (T c up to about 120 K) , but it is widely recognized that the toxicity of thallium would cause serious problems in industrial production.
  • Thallium-based superconducting compounds are highly toxic due to the easy vaporization of TI 2 O3 when heated to temperatures higher than 750°C. This makes it impracticable to employ powder-metallurgy methods needing temperatures of 800°C to 900°C or more.
  • Tl-Ba-Ca-Cu-0 superconductors is a chemical method involving co- precipitation - see the article "Processing Ceramic Superconductors" in the January 1989 Journal of Metals, Page 8, Table II. By this method, fine powders can be prepared, but these powders must then be melted and solidified or sintered at high temperature, giving rise to toxicity problems .
  • EP-A-0 283 024, EP-A-0 286 289 and EP-A-0 305 300 describe methods of making superconducting oxides by oxidation of an alloy precursor made from the component metals elements in the appropriate proportions. These publications do not address the problem of thallium toxicity, should thallium be present.
  • the method according to the invention overcomes the problem of thallium toxicity by :
  • the mixture of compounds that are melted to form the precursor alloy can include TlBa, TlCa, TlCu, Tl2Ba, TlBa 2 and l 3 BaCa.
  • the latter may be present as an alloy of the compounds TlCa and Tl 2 Ba, or as a ternary intermetallic compound, or a mixture of these.
  • the starting materials can also include intermetallic compounds of the other metals, such as BaCa, CaCu or the metals Ba, Ca, Cu, or others .
  • Metallic thallium should not be present in the starting materials.
  • the starting materials can include TlCu, TlBa,
  • TlBa2, l2Ba and suitable compounds of thallium with the other metals are suitable compounds of thallium with the other metals.
  • the thallium intermetallic compounds and optionally one or more intermetallic compounds of the other component metals used in the mixture for forming the precursor alloy is/are prepared by. melting thallium and/or the other component metal (s) in an inert atmosphere, for example under Argon at 500-700 millibars.
  • thallium-based intermetallic compounds in the mixture for forming the precursor alloy takes advantage of the relatively high congruent melting point of these compounds, 805°C for BaTl, 980°C for CaTl.
  • the thallium remains tightly bonded during oxidation and there is a direct path formation of complex oxides without any formation of toxic TI2O3.
  • the temperature during oxidation should not exeed 860°C because above this temperature, the stability of the complex oxycompounds is affected and there is a risk of TI 2 O3 formation.
  • TlBa2Cu ⁇ 6 For the compound TlBa2Cu ⁇ 6, it has been found that a temperature less than 700°C or even about 600°C is adequate during oxidation. For other compounds, for instance TlBa2Ca3Cu 4 ⁇ o.5 temperatures close to 860°C can be used. At 860°C, significant weight losses occur leading to release of toxic compounds . This temperature therefore must not be exceeded.
  • the precursor alloy can be formed into a desired shape prior to oxidation, for example it can be rolled into a strip of sheet, or drawn into a wire. This shaped alloy can then be oxidised to form the superconducting material in a desired shape for its intended use.
  • the oxidation is preferably substantially complete, but may be a partial oxidation through the material, or a surface oxidation only. A non-stoichiometry of oxygen may be beneficial for superconductivity.
  • the oxide may be wholly composed of superconducting phases, or may be a mixture of superconducting and non-superconducting phases .
  • Fig. 1 is a graph or thermogram illustrating an example of the conditions during the oxidation step of the method according to the invention
  • Fig. 2 is a graph illustrating the real component of the magnetic susceptibility of a superconduc ing material obtained according to the invention, from which the critical temperatures of the material can be determined;
  • Fig. 3 is a graph similar to Fig. 1 for preparation of another material.
  • Figs. 4a and 4b are graphs similar to Fig. 2 showing the critical temperatures of the material of Fig 3.
  • the ternary metallic Tl-Ba-Cu system with a nominal composition TlBa 2 Cu3 was melted in an arc furnace under an argon atmosphere starting from precursors TlBa, BaCu and 2Cu.
  • the TlBa and BaCu were previously prepared by arc melting Tl ingots (99.995% pure), Ba (99.7%) and Cu (99.999%) shots from Cerac Company.
  • BaTl and BaCu are congruent melting intermediate compounds at 805°C and 570°C respectively.
  • the resultant alloy was extremely brittle and dense.
  • a small piece thereof .(165.4 Mg) was analyzed by Differencial Thermal Analysis coupled with thermo- gravimetry (DTA/TG) under oxygen flow.
  • the thermogram in Fig. 1 indicates a continuous weight increase (curve A) from room temperature to 700°C while violent exothermic reactions (curve B) observed at 350°C and 650°C correspond to the formation of single, binary or ternary oxides. Violent exothermic formation of the mixed oxides favours macroscopic homogeneity.
  • This experiment clearly indicated that for this composition no thallium vaporization nor thallium-oxide decomposition occured up to 700°C during the oxidation treatment.
  • a 700°C isothermal heat treatment was thus performed on a sample of the lBa 2 Cu3 in flowing oxygen for 48 hours to convert it to the oxide.
  • the magnetic susceptibilities of the specimens submitted to DTA/TG and of the annealed sample were measured in order to detect the superconducting transition and the amount of superconducting phase.
  • For the DTA/TG specimen two transition temperatures were observed at 94 K and 20 K, as shown in Fig. 2.
  • the amount of superconducting phase is low (3 %) but 94 K is, to our knowledge, higher than any previously-reported critical temperature measured in ternary thallium-based materials. Increasing the' duration of the oxidising heat treatment beyond 48 hours was found not to improve the superconducting characteristics.
  • Example 2 In a similar way to Example 1, an alloy corresponding to TlBa 2 Cu was prepared starting from an equimolar mixture of TlBa and BaCu. After the DTA/TG and the isothermal oxidizing treatment, a small amount (0.6 % and 0.4 %) of superconducting phase was found at 90K and 20K.

Landscapes

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • Ceramic Engineering (AREA)
  • Materials Engineering (AREA)
  • Structural Engineering (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Inorganic Chemistry (AREA)
  • Inorganic Compounds Of Heavy Metals (AREA)

Abstract

A method of manufacturing a thallium-based cuprate superconducting ceramic corresponding to the formula: TlBa2Can-1CunO2n+3, where 1 « n « 4 or Tl2Ba2Can-1CunO2n+4, where 1 « n « 5, or various derived systems, overcomes the problem of thallium toxicity by forming a precursor alloy of thallium with the other component metals in the stoichiometric amount corresponding to the final ceramic, by melting in an inert atmosphere a mixture of the component metals wherein the thallium is initially present as at least one intermetallic compound with one or two other component metals. The precursor alloy is then heated in an oxidising atmosphere, at a temperature up to 860 °C, to convert the alloy into the desired thallium-based cuprate material. The thallium intermetallic compound in the precursor alloy may be TlBa, TlCa, TlCu, Tl2Ba, TlBa2, Tl3Ca or Tl3BaCu.

Description

A METHOD OF MANUFACTURING SUPERCONDUCTING CERAMICS
Field of the Invention
The invention relates to methods of manufacturing thallium-based cuprate superconducting ceramics .
Background of the Invention
Since the breakthrough in critical temperatures achieved towards the end of 1986 (EP-A-275 343 and EP-A- 274 407) , there has been considerable activity in superconducting materials and their methods of manufacture .
Superconducting thallium compounds are amongst the most promising known superconducting materials from the point of view of the critical temperatures achieved (Tc up to about 120 K) , but it is widely recognized that the toxicity of thallium would cause serious problems in industrial production. Thallium-based superconducting compounds are highly toxic due to the easy vaporization of TI2O3 when heated to temperatures higher than 750°C. This makes it impracticable to employ powder-metallurgy methods needing temperatures of 800°C to 900°C or more.
One proposal for preparing Tl-Ba-Ca-Cu-0 superconductors is a chemical method involving co- precipitation - see the article "Processing Ceramic Superconductors" in the January 1989 Journal of Metals, Page 8, Table II. By this method, fine powders can be prepared, but these powders must then be melted and solidified or sintered at high temperature, giving rise to toxicity problems .
An article presented by Early et Al. at the TMS Symposium on High Temperatures Superconducting Oxides at Las Vegas, February 27th - March 2nd 1989 disclosed the production of high Tc superconducting Y-Ba-CuO oxides by induction melting the metallic elements with silver at 1000°C, then heating at 900°C under oxygen for 36 hours followed by slow cooling. Tests were carried out with ductile precursors containing 90 % silver in order to overcome the problem of brittleness.
To date, all methods of preparing thallium based superconductors by heat-treating at temperatures above 750°C or so have given rise to problems of toxicity, and methods of production involving heat treatments below this temperature have not produced performing superconductors of high quality.
EP-A-0 283 024, EP-A-0 286 289 and EP-A-0 305 300 describe methods of making superconducting oxides by oxidation of an alloy precursor made from the component metals elements in the appropriate proportions. These publications do not address the problem of thallium toxicity, should thallium be present.
Summary of the Invention
The invention relates to a method of manufacturing a thallium based cuprate superconducting ceramic corresponding to the formula lBa2Can_ιCunθ2n+3/ where 1 <. n <. 4, or Tl2Ba2Can-ιCunθ2n+4/ where 1 ≤. n < 5, or the derived systems (Tl, Pb) (Sr, La) 2C Os and (Tl, Pb, Bi)m(Sr Ba) 2CuOm+4, where m = 1 or 2, this method involving the oxidation of an alloy precursor.
The method according to the invention overcomes the problem of thallium toxicity by :
a) forming a precursor alloy of thallium with the other component metals in the stoichiometric amount corresponding to the final ceramic, by melting in an inert atmosphere a mixture of the component metals wherein the thallium is initially present as at least one intermetallic compound with one or two other component metals, and
b) then heating the precursor alloy in an oxidising atmosphere, at a temperature up to 860°C, to convert the alloy into the desired thallium-based cuprate material. This oxidation can take place in static or flowing oxygen, air or another oxidising atmosphere.
The mixture of compounds that are melted to form the precursor alloy can include TlBa, TlCa, TlCu, Tl2Ba, TlBa2 and l3BaCa. The latter may be present as an alloy of the compounds TlCa and Tl2Ba, or as a ternary intermetallic compound, or a mixture of these. The starting materials can also include intermetallic compounds of the other metals, such as BaCa, CaCu or the metals Ba, Ca, Cu, or others . Metallic thallium, however, should not be present in the starting materials. For the above mentioned derived systems, the starting materials can include TlCu, TlBa,
TlBa2, l2Ba and suitable compounds of thallium with the other metals.
Tests have demonstrated that if the process is carried out with metallic thallium in the starting mixture (as opposed to all thallium being part of intermetallic compounds) , not only is there a risk associated with thallium toxicity, but the properties of the resulting superconducting material are also inferior.
The thallium intermetallic compounds and optionally one or more intermetallic compounds of the other component metals used in the mixture for forming the precursor alloy is/are prepared by. melting thallium and/or the other component metal (s) in an inert atmosphere, for example under Argon at 500-700 millibars.
Using thallium-based intermetallic compounds in the mixture for forming the precursor alloy takes advantage of the relatively high congruent melting point of these compounds, 805°C for BaTl, 980°C for CaTl.
By performing the subsequent oxidation below these melting temperatures, the thallium remains tightly bonded during oxidation and there is a direct path formation of complex oxides without any formation of toxic TI2O3. In any event, however, the temperature during oxidation should not exeed 860°C because above this temperature, the stability of the complex oxycompounds is affected and there is a risk of TI2O3 formation.
For the compound TlBa2Cuθ6, it has been found that a temperature less than 700°C or even about 600°C is adequate during oxidation. For other compounds, for instance TlBa2Ca3Cu4θιo.5 temperatures close to 860°C can be used. At 860°C, significant weight losses occur leading to release of toxic compounds . This temperature therefore must not be exceeded.
By selecting the appropriate metallic concentration in the metallic phase, the formation of a BaCuθ2 phase which is detrimental to the superconducting properties is minimized.
After cooling, the precursor alloy can be formed into a desired shape prior to oxidation, for example it can be rolled into a strip of sheet, or drawn into a wire. This shaped alloy can then be oxidised to form the superconducting material in a desired shape for its intended use.
The oxidation is preferably substantially complete, but may be a partial oxidation through the material, or a surface oxidation only. A non-stoichiometry of oxygen may be beneficial for superconductivity. The oxide may be wholly composed of superconducting phases, or may be a mixture of superconducting and non-superconducting phases .
Brief Description of the Drawings
In the accompanying drawings :
Fig. 1 is a graph or thermogram illustrating an example of the conditions during the oxidation step of the method according to the invention; Fig. 2 is a graph illustrating the real component of the magnetic susceptibility of a superconduc ing material obtained according to the invention, from which the critical temperatures of the material can be determined;
Fig. 3 is a graph similar to Fig. 1 for preparation of another material; and
Figs. 4a and 4b are graphs similar to Fig. 2 showing the critical temperatures of the material of Fig 3.
Detailed Description
The invention will be further illustrated in the following Examples.
Example 1
The ternary metallic Tl-Ba-Cu system with a nominal composition TlBa2Cu3 was melted in an arc furnace under an argon atmosphere starting from precursors TlBa, BaCu and 2Cu. The TlBa and BaCu were previously prepared by arc melting Tl ingots (99.995% pure), Ba (99.7%) and Cu (99.999%) shots from Cerac Company. BaTl and BaCu are congruent melting intermediate compounds at 805°C and 570°C respectively.
The resultant alloy was extremely brittle and dense. A small piece thereof .(165.4 Mg) was analyzed by Differencial Thermal Analysis coupled with thermo- gravimetry (DTA/TG) under oxygen flow. The thermogram in Fig. 1 indicates a continuous weight increase (curve A) from room temperature to 700°C while violent exothermic reactions (curve B) observed at 350°C and 650°C correspond to the formation of single, binary or ternary oxides. Violent exothermic formation of the mixed oxides favours macroscopic homogeneity. This experiment clearly indicated that for this composition no thallium vaporization nor thallium-oxide decomposition occured up to 700°C during the oxidation treatment.
A 700°C isothermal heat treatment was thus performed on a sample of the lBa2Cu3 in flowing oxygen for 48 hours to convert it to the oxide. The magnetic susceptibilities of the specimens submitted to DTA/TG and of the annealed sample were measured in order to detect the superconducting transition and the amount of superconducting phase. For the DTA/TG specimen, two transition temperatures were observed at 94 K and 20 K, as shown in Fig. 2. The amount of superconducting phase is low (3 %) but 94 K is, to our knowledge, higher than any previously-reported critical temperature measured in ternary thallium-based materials. Increasing the' duration of the oxidising heat treatment beyond 48 hours was found not to improve the superconducting characteristics. Example 2
In a similar way to Example 1, an alloy corresponding to TlBa2Cu was prepared starting from an equimolar mixture of TlBa and BaCu. After the DTA/TG and the isothermal oxidizing treatment, a small amount (0.6 % and 0.4 %) of superconducting phase was found at 90K and 20K.
Example 3
A preliminary study of the quaternary Tl-Ba-Ca-Cu system was undertaken for the nominal composition TlBa2Ca3Cu4 obtained by melting a mixture of TlBa + BaCu and CaCu in the ratio 1:1:3. Like the ternary system, the DTA/TG diagram in Fig. 3 demonstrates continuous weight increase and a series of exothermic reactions. A long (48 hours) oxidation treatment at 700°C was performed. The susceptibility measurements on two specimens are displayed in Figs. 4a and 4b. Very encouraging results were obtained with transition temperatures of 124K and 110K and amounts of superconducting phases up to 30% (in the DTA/TG sample) . From SEM/EDX and X-ray diffraction investigations it appears that the samples are multiphase, one of the quaternary oxidised compounds being TlBa2CaCu2θ a known compound of the TlBa2Can_ιCun series . The sample was found to melt at 901 ± 5°C. Significant weight losses were found to occur in the premelting range (T ___ 875°C) . A flash anneal up to 865°C drastically increased the amount of superconducting phases up to nearly 100 %. Nevertheless the material remains at least two-phase. Further work is directed to obtain single phase compounds of similar composition.

Claims

C A I M S
A method of manufacturing a thallium-based cuprate superconducting ceramic corresponding to the formula
TlBa2Can-ιCun02n+3 where 1 < n < 4, Tl2BaCan-iCun02n+4 where 1 ≤ n < 5,
or the derived systems
(Tl, Pb) (Sr, La)2 Cu05 and (Tl, Pb, Bi)m(Sr, Ba)2 CuOm+4
where m = 1 or 2,
by oxidation of an alloy precursor, characterized in that the method comprises :
a) forming a precursor alloy of thallium with the other component metals in the stoichiometric amount for the final ceramic, by melting in an inert atmosphere a mixture of the component metals wherein the thallium is initially present in at least one intermetallic compound with one or two other component metals; and
b) heating said precursor alloy in an oxidizing atmosphere at a temperature up to 860°C to convert the alloy into the desired thallium-based cuprate material .
2. The method of claim 1 wherein the thallium is initially present in the mixture for forming the precursor alloy as one or more of the intermetallic compounds TlBa, TlBa2, TlCa, TlCu, Tl2Ba, Tl3Ca or Tl3BaCu.
3. The method of claim 1 or 2 wherein the thallium intermetallic compound and optionally one or more intermetallic compounds of the other component metals used in the mixture for forming the precursor alloy is/are prepared by melting thallium and/or the other component metal (s) in an inert atmosphere, for example under Argon at 500-700 millibars.
4. The method of any preceding claim for manufacturing TlBa2C θ6 wherein the precursor alloy is heated in an oxidising atmosphere at a temperature up to 700°C, possibly up to 600°C.
5. The method of any one of claims 1 to 3 for manufacturing TlBa2Ca3Cu θιo.5 wherein the precursor alloy is heated in an oxidising atmosphere at a temperature close to 860°C.
6. The method of any preceding claim wherein the precursor alloy is rolled into a strip or sheet - or drawn into a wire prior to oxidation.
PCT/EP1991/000574 1990-04-02 1991-03-19 A method of manufacturing superconducting ceramics Ceased WO1991015436A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
EP90810263 1990-04-02
EP90810263.5 1990-04-02

Publications (1)

Publication Number Publication Date
WO1991015436A1 true WO1991015436A1 (en) 1991-10-17

Family

ID=8205916

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP1991/000574 Ceased WO1991015436A1 (en) 1990-04-02 1991-03-19 A method of manufacturing superconducting ceramics

Country Status (2)

Country Link
AU (1) AU7549191A (en)
WO (1) WO1991015436A1 (en)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB9008753D0 (en) * 1990-04-19 1990-06-13 Lynxvale Ltd Superconductors

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0283024A2 (en) * 1987-03-20 1988-09-21 Sumitomo Electric Industries Limited Method of manufacturing a ceramic superconductor
EP0286289A1 (en) * 1987-03-27 1988-10-12 Massachusetts Institute Of Technology A method of preparing a superconducting oxide and superconducting oxide metal composites
EP0305300A2 (en) * 1987-08-28 1989-03-01 Sumitomo Electric Industries Limited A method for producing a superconducting article

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0283024A2 (en) * 1987-03-20 1988-09-21 Sumitomo Electric Industries Limited Method of manufacturing a ceramic superconductor
EP0286289A1 (en) * 1987-03-27 1988-10-12 Massachusetts Institute Of Technology A method of preparing a superconducting oxide and superconducting oxide metal composites
EP0305300A2 (en) * 1987-08-28 1989-03-01 Sumitomo Electric Industries Limited A method for producing a superconducting article

Also Published As

Publication number Publication date
AU7549191A (en) 1991-10-30

Similar Documents

Publication Publication Date Title
EP0286289B1 (en) A method of preparing a superconducting oxide and superconducting oxide metal composites
US4826808A (en) Preparation of superconducting oxides and oxide-metal composites
EP0295023B1 (en) Method of fabricating a superconductive body, and apparatus and systems comprising the body
US6475311B1 (en) Alloy materials
US6284712B1 (en) Processing of oxide superconductors
US5591698A (en) Low temperature (T lower than 950° C.) preparation of melt texture YBCO superconductors
WO1991015436A1 (en) A method of manufacturing superconducting ceramics
US5273959A (en) Alloy for HTSC composite conductors made of Au-Ag-Pd
US5229357A (en) Method of producing superconducting ceramic wire and product
US20090048114A1 (en) Alloy superconductor and methods of making the same
Schartman et al. Supersolidus Phase Investigation of the Bi‐Sr‐Ca‐Cu Oxide System in Silver Tape
Inoue et al. Superconducting properties and microstructure of crystallized Hf-Nb-Si and Hf-V-Si amorphous alloys
JP2566942B2 (en) Method for producing compound superconducting wire
JP3174847B2 (en) Superconducting whisker and manufacturing method thereof
Matsuzaki et al. Preparation of oxide superconductors by oxidation of amorphous Ln-Ce-Cu(Ln= Pr, Nd or Sm) alloy tapes
JP3167316B2 (en) Method for producing Tl-based oxide superconductor
JPH0714818B2 (en) Superconducting fibrous crystal and method for producing the same
JPH04214061A (en) Productionof tl-based oxide superconductor
Concalves et al. Preparation of superconductors of the BiSrCaCuO system by glass crystallization
JPH03112810A (en) Production of oxide superconducting film
CA2083566A1 (en) Alloy for htsc composite conductors
Tachikawa et al. High-Field A15 Superconductors Prepared Via New Routes
Tachikawa et al. High-Field A-15 Superconductors Prepared from Intermediate Compound
JPH0717380B2 (en) Method for producing superconducting fibrous crystal
Grosav et al. Composite superconducting wires obtained by high-rate tinning in molten Bi-Pb-Sr-Ca-Cu-O system

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A1

Designated state(s): AU CA JP KR SU US

AL Designated countries for regional patents

Kind code of ref document: A1

Designated state(s): AT BE CH DE DK ES FR GB GR IT LU NL SE

NENP Non-entry into the national phase

Ref country code: CA