WO1990002421A1 - Treatment of superconducting materials - Google Patents

Treatment of superconducting materials Download PDF

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Publication number
WO1990002421A1
WO1990002421A1 PCT/GB1989/000985 GB8900985W WO9002421A1 WO 1990002421 A1 WO1990002421 A1 WO 1990002421A1 GB 8900985 W GB8900985 W GB 8900985W WO 9002421 A1 WO9002421 A1 WO 9002421A1
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Prior art keywords
titration
oxygen
superconducting
superconducting material
treated
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PCT/GB1989/000985
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French (fr)
Inventor
Jan Edgar Evetts
Derek John Fray
Judith Louise Macmanus
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Cambridge Advanced Materials Limited
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Publication of WO1990002421A1 publication Critical patent/WO1990002421A1/en

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    • 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
    • C04B35/4508—Type 1-2-3
    • 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 the treatment of superconducting materials, and may be used to enhance the current carrying capability of superconducting materials, particularly high critical temperature superconductors based on ceramic materials.
  • a method of treatment of a ceramic based superconducting material wherein a species which is mobile in the material is titrated into or out of the material so as to alter the orientation of the grains within the material in such a way as to enhance the current carrying capabilities of the material.
  • Treatment by the method of the invention results in the formation of an elongated textured microstructure of the treated material.
  • a textured structure those planes in which the current usually flows through the superconducting material are aligned to a greater extent than in the untextured structure, thus allowing current to flow more easily through the material.
  • the textured structure is therefore beneficial for supporting a high critical current density in the superconducting material.
  • the method may be used- to advantage on any ceramic based superconducting material, such as various known oxides, not having a cubic microstructure, eg one having an orthorhombic structure.
  • the method of the present invention is particularly applicable to treatment of materials having oxygen vacancies in their microstructure, and hence a degree of variability in their stoichiometry with regard to any mobile constituent species.
  • materials might include, for example:-
  • x, y and z are any suitable number dictated by the stoichiometry.
  • the currently most preferred materials are those having the general formula YBa 2 Cu_0, 7 _ -. where, typically, x is between 0 and 1 inclusive.
  • superconductor and superconducting material as employed herein are intended to mean materials which are capable of superconductivity
  • the mobile species may comprise, eg, oxygen, fluorine or copper, with oxygen conveniently being titrated out of the material and fluorine conveniently being titrated into the material for instance.
  • Titration of the oxygen or other mobile species may be achieved electrochemically using a solid electrolyte fast ionic conductor in contact with the ceramic superconductor.
  • ionic conductors suitable for oxygen titration are Y ⁇ 3 .Zr0 2 , CaO.ZrO_, with the preferred ionic conductor for use for oxygen titration in the method of the present invention being, Bi ⁇ c .Y ⁇ 0-> .
  • LaF_ and other fluoride ion conductors may be used.
  • the superconducting material to be treated is placed in surface contact with a sample of the ionic conductor, and a source of e f connected across the materials.
  • the voltage applied is typically between 0.5 and 2 V.
  • the temperature used during titration is conveniently such that the mobile species has a suitably high rate of diffusion through the superconducting material.
  • the temperature is preferably above 400°C, more preferably about 600°C. The titration should continue for sufficient time to allow a significant proportion of the mobile species to diffuse in or out as required.
  • This time period naturally depends* on the nature and the volume of the superconducting material being treated, and on the nature of the mobile species itself. Treatment times of up to ten hours, preferably between 3 and 6 hours, have been found to be effective in typical cases.
  • Titration may alternatively be achieved by heating the material to be treated in a pressure gradient of the mobile species, eg with one face of the material exposed to a vacuum or a gas with low a pressure of oxygen and an opposed face exposed to a gas with a high pressure of oxygen, and heating the material to a suitable temperature for a suitable time.
  • the superconducting material can be processed to the required microstructure to give optimum superconducting properties by more than merely one titration step, and a plurality of titration steps may be employed to achieve optimum superconducting properties.
  • a ceramic based superconducting oxide material treated by the method of the invention and a product comprising such a material.
  • the superconducting material may additionally be treated in any required manner and used in the production of any required products.
  • the material may be electroche ically adjusted into its optimum composition and state of oxidation or valence state so as to maximise its superconducting properties, as described in copending International Application No PCT/GB88/00381 (WO88/09061) .
  • the material may form part of a composite with suitable cladding and internal structure, as described in copending International Application No PCT/GB88/00330 (WO88/08618) .
  • the ceramic superconducting material to be treated was of the class of compounds YBa «Cu_o, 7 _ -. where, typically, x is between 0 and 1 inclusive. Techniques for producing such materials are well known to those skilled in the art. After a five-hour equilibration in air, electrochemical titration of oxygen out of this material was achieved as follows.
  • a disc-shaped pellet of the material was placed adjacent to a similar-sized pellet of an ionic conductor, with their adjacent circular faces in surface contact.
  • Any suitable ionic conductor could be used, for instance Bi 2 0 3 .Y 2 0 3 , Y 2 0 3 .Zr0 2 or CaO.Zr0 2 , but in this case the preferred conductor was Bi_ ⁇ - .Y_0_ .
  • the ionic conductor was connected to the positive pole of a source of emf, and the superconducting material to the negative pole, each via a respective platinum electrode.
  • the voltage applied was between 0.5 and 2 V.
  • the application of a potential difference across the two pellets served to impose an oxygen activity gradient across the pellets, causing the diffusion of oxygen out of the superconducting material and through the ionic conductor .
  • This titration process was allowed to continue for five hours, during which time the materials were held at 600°C in a furnace. Since the diffusi'on rate of oxygen through a superconducting material increases with temperature, it is necessary to use a reasonably high temperature for the titration process in order to achieve a significant amount of oxygen diffusion. Thus any temperature above 400°C would be suitable for this material. The maximum temperature which could be used would depend on the melting point of the ionic conductor or of the superconducting material itself.
  • the material was permitted to cool slowly in air back to room temperature, by switching the furnace off and leaving the material to cool overnight in the furnace .
  • the starting sample having its normal oxygen content, was labelled f, and samples after each of the five subsequent treatment steps outlined above re-labelled g, h, i, j and k, respectively.
  • an X-ray diffraction pattern was taken of the sample, and the intensities of key peaks measured. The results are shown in the table below. Each figure represents the intensity of a particular peak (as measured by the area under that peak) relative to the 103/110 peak, which results from X- ray diffraction at a particular set of planes hkl in the superconductor structure.
  • the degree of texturing was strongly dependent on the oxygen flux from the material, as sample g, where the measured current density was approximately 22 mA/cm , had a more highly textured structure than sample i, where the current density was approximately 14 mA/cm .
  • the texturing achieved corresponds to the alignment of the
  • the amount of mechanical working on a brittle superconducting material could also be reduced if samples were initially textured by electrochemical titration in accordance with the present invention.
  • fluorine was electrochemically titrated into a sample of the same ceramic superconducting material as was used in Example 1, ' ie YBa 2Cu 3_0, (-7,-x.)..
  • a disc shaped pellet of the material was placed adjacent to a similarly sized pellet of the fluoride ion conductor LaF_, with adjacent circular faces in surface contact.
  • the silver/silver fluoride was connected to the negative pole of a source of e f , and the superconducting material to the positive pole, each via a respective platinum electrode.
  • a voltage of 1 V was applied, imposing a fluorine activity gradient across the pellets and causing diffusion of fluorine from the silver/silver fluoride, through the ionic conductor and into the superconducting material .
  • the fluorine titration process was allowed to continue for about 1 hour, during which time the materials were held at a temperature of 430°C in a furnace. After the titration treatment, the material was permitted to cool, as described in Example 1.
  • a scanning electron microscopy study of the pellet after treatment revealed elongated grains on the titrated surface of the superconductor.
  • the grains were aligned with the c direction perpendicular to the surface of the pellet.
  • the grains were not of a second phase but still of the superconducting Y 1 Ba 2 Cu 3 O ⁇ or Y*-_Ba 2 Cu 3 O ⁇ F phases.
  • the current density of the material after treatment was 64

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

Abstract

A method of treatment of a ceramic based superconducting material comprises titrating into or out of the material oxygen or any other species which is mobile in the material. The treatment serves to alter the grain orientation within the superconducting material in such a way as to enhance its current carrying capabilities. The method is best suited for treating ceramic based superconducting materials which are non-cubic in their microstructure and which have a degree of variability in their stoichiometry. In particular, compounds of the type YBa2Cu3O(7-x), where x is between 0 and 1 inclusive, can be treated by the method of the invention.

Description

Title: Treatment of Superconducting Materials
Field of the Invention
This invention concerns the treatment of superconducting materials, and may be used to enhance the current carrying capability of superconducting materials, particularly high critical temperature superconductors based on ceramic materials.
Background to the Invention
Although superconducting components and wires have been available for some years they have in general been based on metallic compounds. Examples of existing commercial materials are NbTi alloys and A15 intermetallic compounds such as Nb_Sn. A new class of very high critical temperature, high magnetic field, superconducting oxide phases (known as ceramic superconductors), presents new opportunities for applications of superconductivity but raises new problems associated with the design of components and wires, because of the brittle nature of the material involved. It is likely that other ceramic superconducting materials (such as sulphur nitride, and molybdenum nitride) will present similar problems.
The brittle nature of ceramics makes it difficult to achieve in a controlled way the special microstructures that are essential if these materials are to support the large superconducting current density necessary for most commercial applications. It is therefore desirable to be able to produce a ceramic superconducting material with enhanced current carrying capabilities.
Summary of the Invention
According to a first aspect of the invention there is provided a method of treatment of a ceramic based superconducting material, wherein a species which is mobile in the material is titrated into or out of the material so as to alter the orientation of the grains within the material in such a way as to enhance the current carrying capabilities of the material.
Treatment by the method of the invention results in the formation of an elongated textured microstructure of the treated material. In such a textured structure, those planes in which the current usually flows through the superconducting material are aligned to a greater extent than in the untextured structure, thus allowing current to flow more easily through the material. The textured structure is therefore beneficial for supporting a high critical current density in the superconducting material.
The method may be used- to advantage on any ceramic based superconducting material, such as various known oxides, not having a cubic microstructure, eg one having an orthorhombic structure.
The method of the present invention is particularly applicable to treatment of materials having oxygen vacancies in their microstructure, and hence a degree of variability in their stoichiometry with regard to any mobile constituent species. These materials might include, for example:-
1. Compounds of the type BiSrCaCuO, eg:
Bi2Sr2Ca2Cu2°(8+y) Bi2Sr2Ca2Cu3Oy
Bi4Sr3Ca3Cu4Oy Bi4Sr3Ca3Cu6Oy
(Bi(l-x)Pbx)2Sr2Ca2Cu30(lO+z)
d,„ ce CuO, . . (2-x) x (4-y)
Tl2B 2CaCu208 or Tl2B 2Ca2Cu3θχ
YlBa2Cu3°(7-x) YlBa2Cu408
YlBa2CU3.5°(7+x) YlBa2Cu3OχFy
In the above formulae, x, y and z are any suitable number dictated by the stoichiometry.
The currently most preferred materials are those having the general formula YBa2Cu_0,7_ -. where, typically, x is between 0 and 1 inclusive.
To avoid doubt the expressions superconductor and superconducting material as employed herein are intended to mean materials which are capable of superconductivity,
The mobile species may comprise, eg, oxygen, fluorine or copper, with oxygen conveniently being titrated out of the material and fluorine conveniently being titrated into the material for instance.
Titration of the oxygen or other mobile species may be achieved electrochemically using a solid electrolyte fast ionic conductor in contact with the ceramic superconductor. Examples of ionic conductors suitable for oxygen titration are Y^θ3.Zr02, CaO.ZrO_, with the preferred ionic conductor for use for oxygen titration in the method of the present invention being, Bi^c .Y~0-> . For fluorine titration, LaF_ and other fluoride ion conductors may be used.
Typically, the superconducting material to be treated is placed in surface contact with a sample of the ionic conductor, and a source of e f connected across the materials. The voltage applied is typically between 0.5 and 2 V.
In the case of, for instance, oxygen titration, the application of this voltage across the superconducting material and the ionic conductor serves to impose an oxygen activity gradient across them, thereby causing oxygen to diffuse out of the superconducting material into the ionic conductor.
The temperature used during titration is conveniently such that the mobile species has a suitably high rate of diffusion through the superconducting material. In the case of compounds of the type YBa2cu30 7_x) where oxygen is the species to be titrated out, the temperature is preferably above 400°C, more preferably about 600°C. The titration should continue for sufficient time to allow a significant proportion of the mobile species to diffuse in or out as required.
This time period naturally depends* on the nature and the volume of the superconducting material being treated, and on the nature of the mobile species itself. Treatment times of up to ten hours, preferably between 3 and 6 hours, have been found to be effective in typical cases.
On cooling in air after such treatment, it is found that some oxygen may enter or re-enter the material, possibly decreasing the desired texturing. For this reason, it may be desirable to treat an oxide which contains more than the required amount of oxygen, with the excess oxygen then being titrated out by the method of the invention.
Titration may alternatively be achieved by heating the material to be treated in a pressure gradient of the mobile species, eg with one face of the material exposed to a vacuum or a gas with low a pressure of oxygen and an opposed face exposed to a gas with a high pressure of oxygen, and heating the material to a suitable temperature for a suitable time.
The superconducting material can be processed to the required microstructure to give optimum superconducting properties by more than merely one titration step, and a plurality of titration steps may be employed to achieve optimum superconducting properties.
According to further aspects of the invention there are provided a ceramic based superconducting oxide material treated by the method of the invention, and a product comprising such a material.
Before and/or after treatment in accordance with the present invention, the superconducting material may additionally be treated in any required manner and used in the production of any required products. For instance, the material may be electroche ically adjusted into its optimum composition and state of oxidation or valence state so as to maximise its superconducting properties, as described in copending International Application No PCT/GB88/00381 (WO88/09061) . Further, the material may form part of a composite with suitable cladding and internal structure, as described in copending International Application No PCT/GB88/00330 (WO88/08618) .
The invention will now be further described, by way of illustration, in the following Examples.
Example 1
The ceramic superconducting material to be treated was of the class of compounds YBa«Cu_o,7_ -. where, typically, x is between 0 and 1 inclusive. Techniques for producing such materials are well known to those skilled in the art. After a five-hour equilibration in air, electrochemical titration of oxygen out of this material was achieved as follows.
A disc-shaped pellet of the material, of diameter approximately 10mm and height approximately 3mm, was placed adjacent to a similar-sized pellet of an ionic conductor, with their adjacent circular faces in surface contact. Any suitable ionic conductor could be used, for instance Bi203.Y203, Y203.Zr02 or CaO.Zr02, but in this case the preferred conductor was Bi_θ- .Y_0_ .
The ionic conductor was connected to the positive pole of a source of emf, and the superconducting material to the negative pole, each via a respective platinum electrode. The voltage applied was between 0.5 and 2 V. The application of a potential difference across the two pellets served to impose an oxygen activity gradient across the pellets, causing the diffusion of oxygen out of the superconducting material and through the ionic conductor .
This titration process was allowed to continue for five hours, during which time the materials were held at 600°C in a furnace. Since the diffusi'on rate of oxygen through a superconducting material increases with temperature, it is necessary to use a reasonably high temperature for the titration process in order to achieve a significant amount of oxygen diffusion. Thus any temperature above 400°C would be suitable for this material. The maximum temperature which could be used would depend on the melting point of the ionic conductor or of the superconducting material itself.
After the titration treatment, the material was permitted to cool slowly in air back to room temperature, by switching the furnace off and leaving the material to cool overnight in the furnace .
In this experiment, the effect of cycling oxygen into and out of the same sample of superconducting material was investigated. The sample was accordingly subjected to a series of successive treatment steps as follows:- (i) oxygen removal by electrochemical titration, followed by slow cooling in air;
(ii) annealing in air (ie heating the sample for 5 hours, but without application of a potential) ;
(iii) oxygen removal and cooling as in (i);
(iv) annealing in air as in (ii);
(v) oxygen removal and cooling as in (i).
The starting sample, having its normal oxygen content, was labelled f, and samples after each of the five subsequent treatment steps outlined above re-labelled g, h, i, j and k, respectively. After each treatment, an X-ray diffraction pattern was taken of the sample, and the intensities of key peaks measured. The results are shown in the table below. Each figure represents the intensity of a particular peak (as measured by the area under that peak) relative to the 103/110 peak, which results from X- ray diffraction at a particular set of planes hkl in the superconductor structure.
Figure imgf000011_0001
The results clearly show that after oxygen removal by titration (samples g, i and k) the superconducting material became textured, with significant re-alignment of the "c" axis orientation relative to the circular surface of the pellet of the material . This was evidenced by increases in the intensities of the 014/005 and 020/006 peaks following titration steps. The corresponding intensities for the 113, 200, 123/116 and 213 peaks decreased as expected, these planes being oriented away from the planes of type 001, all of which lie perpendicular to the "c" axis.
The degree of texturing was strongly dependent on the oxygen flux from the material, as sample g, where the measured current density was approximately 22 mA/cm , had a more highly textured structure than sample i, where the current density was approximately 14 mA/cm .
A final X-ray diffraction pattern taken on the sample after slow cooling was almost identical in the peak positions to that taken for sample g, indicating that the final slow cooling step had allowed the sample to re- attain its equilibrium oxygen content after the titration steps.
The texturing achieved corresponds to the alignment of the
"c" axis perpendicular to the circular surface of the sample pellet. Since current flows through this type of superconductor, of orthorhombic structure, in the planes perpendicular to the "c" axis, then alignment of these planes allows current to pass more easily through the superconductor. Thus the texturing demonstrated in this experiment would greatly enhance the current carrying capabilities of the treated material, as measured by an increase in the superconducting critical current density which could be supported by the material. It is thought that increases in critical current density by a factor of
3 up to 10 might be possible using the treatment method of the present invention.
The amount of mechanical working on a brittle superconducting material could also be reduced if samples were initially textured by electrochemical titration in accordance with the present invention.
Example 2
In this example, fluorine was electrochemically titrated into a sample of the same ceramic superconducting material as was used in Example 1, ' ie YBa 2Cu 3_0, (-7,-x.)..
A disc shaped pellet of the material , of diameter approximately 10mm and height approxi ately 3mm was placed adjacent to a similarly sized pellet of the fluoride ion conductor LaF_, with adjacent circular faces in surface contact. A further similarly-sized pellet of silver/silver fluoride, which acts as a source of fluoride ions, was placed in contact with the free circular face of the LaF- pellet, forming a sandwich with the LaF_ pellet in the middle.
The silver/silver fluoride was connected to the negative pole of a source of e f , and the superconducting material to the positive pole, each via a respective platinum electrode. A voltage of 1 V was applied, imposing a fluorine activity gradient across the pellets and causing diffusion of fluorine from the silver/silver fluoride, through the ionic conductor and into the superconducting material .
The fluorine titration process was allowed to continue for about 1 hour, during which time the materials were held at a temperature of 430°C in a furnace. After the titration treatment, the material was permitted to cool, as described in Example 1.
A scanning electron microscopy study of the pellet after treatment revealed elongated grains on the titrated surface of the superconductor. The grains were aligned with the c direction perpendicular to the surface of the pellet. Analysis revealed that these grains were comprised of the elements yttrium, barium and copper in the same molar ratios as the starting material. Hence, the grains were not of a second phase but still of the superconducting Y1Ba2Cu3Oχ or Y*-_Ba2Cu3OχF phases.
The current density of the material after treatment was 64
, 2 mA/cm .

Claims

Claims
1. A method of treatment of a ceramic based superconducting material, wherein a species which is mobile in the material is titrated into or out of the material so as to alter the orientation of the grains within the material -in such a way as to enhance the current carrying capabilities of the material.
2. A method according to Claim 1, wherein the superconducting material is a material having oxygen vacancies in its microstructure, and hence a degree of variability in its stoichiometry.
3. A method according to Claim 1, wherein the superconducting material is selected from the following: bismuth strontium calcium copper oxides, neodymium cerium copper oxides, thallium barium calcium copper oxides and yttrium barium copper oxides, and yttrium barium copper oxide fluoride.
4. A method according to Claim 3, wherein the superconducting material is selected from the group of compounds having the general formula YBa.-.Cu.-.O,., , wherein x is between 0 and 1 inclusive.
5. A method according to Claim 1, wherein oxygen is titrated out of the material.
6. A method according to Claim 1, wherein fluorine is titrated into the material.
7. A method according to Claim 1, wherein the titration of the mobile species out of the' material is achieved electrochemically by applying a potential difference across a solid electrolyte fast ionic conductor in surface contact with the superconducting material.
8. A method according to Claim 7, wherein the titration of the mobile species out of the material is carried out at a temperature of greater than 400°C.
9. A method according to Claim 8, wherein titration of oxygen out of the material is carried out at a temperature of about 600°C.
10. A method according to Claim 7, wherein the electrochemical titration is allowed to continue for up to ten hours .
11. A method according to Claim 1, wherein the superconducting material is treated with more than one titration step.
12. A method according to Claim 1, wherein the material treated comprises excess oxygen.
13. A ceramic based superconducting material treated according to the method of Claim 1.
14. A product comprising a ceramic based superconducting material, which material has been treated according to the method of Claim 1.
PCT/GB1989/000985 1988-08-26 1989-08-24 Treatment of superconducting materials WO1990002421A1 (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110423596A (en) * 2019-08-05 2019-11-08 河源帝诺新材料有限公司 A kind of abrasive media titration moulding process

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Publication number Priority date Publication date Assignee Title
JPS6469580A (en) * 1987-09-09 1989-03-15 Yoshiaki Arata Production of superconductor
EP0313964A2 (en) * 1987-10-27 1989-05-03 BASF Aktiengesellschaft Method for adjusting the threshold temperature, the saturation current in the presence or absence of a magnetic field and proportions of normal conductive phases of superconductive ceramics
EP0325526A2 (en) * 1988-01-22 1989-07-26 Thomson-Csf Device made of superconducting material and method of making the same

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS6469580A (en) * 1987-09-09 1989-03-15 Yoshiaki Arata Production of superconductor
EP0313964A2 (en) * 1987-10-27 1989-05-03 BASF Aktiengesellschaft Method for adjusting the threshold temperature, the saturation current in the presence or absence of a magnetic field and proportions of normal conductive phases of superconductive ceramics
EP0325526A2 (en) * 1988-01-22 1989-07-26 Thomson-Csf Device made of superconducting material and method of making the same

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Title
Applied Physics Letters, Vol. 51, No. 8, 24 August 1987, American Institute of Physics (New York, N.Y., US), R. BEYERS et al.: "Annealing Treatment Effects on Structure and Superconductivity in Y1Ba2Cu3O9-x", pages 614-616 *
Applied Physics Letters, Vol. 52, No. 17, 25 April 1988, American Institute of Physics (New York, N.Y., US), E.J.M. O'SULLIVAN et al.: "Study of Oxygen Transport in Ba2YCu3O7-Delta using a Solid-state Electrochemical Cell", pages 1441-1443 *
PATENT ABSTRACTS OF JAPAN, Vol. 13, No. 273 (C-609) (3621), 22 June 1989; & JP-A-64 069580 (Yoshiaki Arata) 15 March 1989 *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110423596A (en) * 2019-08-05 2019-11-08 河源帝诺新材料有限公司 A kind of abrasive media titration moulding process

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