US5474976A
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Production of oxide superconductors having large magnetic levitation force
Assignee: HOKURKU ELECTRIC POWER Co
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Filing: 1993-03-29
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Granted: 1995-12-12
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Expires: 2013-03-29
Abstract
Abstract A method for producing an REBaCuO oxide superconductor having large magnetic levitation force, where RE is a rare earth element selected from the group consisting of Y, Sm, Eu, Gd, Dy, Ho, Er, and Yb, involves the steps of using a raw material mixture as the starting feed, heating the raw material mixture for partial melting, followed by cooling and solidification, pulverizing and mixing the resulting solid, shaping the resulting mixture into a given shape, placing or embedding nucleates on or in the resulting shape, followed by heating for partial melting, and cooling the resulting partial melt to a substantial temperature at which a superconducting phase starts to form, followed by slow cooling, whereby the superconducting phase is preferentially formed and grown from a nucleation site.
Inventors
- 👤 Akihiro Kondoh
- 👤 Masato Murakami
- 👤 Hiroshi Takaichi
- 👤 Naoki Koshizuka
- 👤 Shoji Tanaka
- 👤 Shoichi Kagiya
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 05:39
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/622; C04B35/653; C04B35/01; C04B35/45; C04B35/4504; H; H10; H10N; H10N60/00; H10N60/01; H10N60/0268; H10N60/0828; H10N60/80; H10N60/85; H10N60/855; H10N60/857
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
166 words
A method for producing an RE--Ba--Cu--O oxide superconductor having large magnetic levitation force, where RE is a rare earth element selected from the group consisting of Y, Sm, Eu, Gd, Dy, Ho, Er, and Yb, which involves: providing a starting feed comprising a raw material mixture in powdered form, heating said raw material mixture for partial melting, followed by cooling and solidification of the partially melted raw material mixture to a solid, pulverizing said solid to achieve pulverized powders, mixing said pulverized powders to achieve mixed powders, shaping said mixed powders into a given shape, heating said shape for partial melting to achieve a partial melt, cooling said partial melt to a temperature at which a superconducting phase starts to form, followed by slow cooling, whereby a superconducting phase is formed and grown from a nucleation site, wherein the method further comprises placing or embedding nucleants on or in said shape at any point between completion of said sharing and just prior to said slow cooling.
Claim 2
Independent Claim
166 words
A method for producing an RE--Ba--Cu--O oxide superconductor having large magnetic levitation force, where RE is a rare earth element selected from the group consisting of Y, Sm, Eu, Gd, Dy, Ho, Er, and Yb, which involves: providing a starting feed comprising a raw material mixture in powdered form, heating said raw material mixture for partial melting, followed by cooling and solidification of the partially melted raw material mixture to a solid, pulverizing said solid to achieve pulverized powders, mixing said pulverized powders to achieve mixed powders, shaping said mixed powders into a given shape, heating said shape for partial melting to achieve a partial melt, cooling said partial melt to a temperature at which a superconducting phase starts to form, followed by slow cooling, whereby a superconducting phase is formed and grown from a nucleation site, wherein the method further comprises placing or embedding nucleants on or in said shape at any point between completion of said sharing and just prior to said slow cooling.
Claim 3
Dependent Claim
26 words
A method according to claim 1, wherein said nucleants are placed or embedded in the shape prior to said heating of said shade for partial melting.
Claim 4
Dependent Claim
111 words
A method according to claim 1, wherein said nucleants are a rare earth element-containing oxide selected from the group consisting of Y 2 O 3 , Nd 2 O 3 , Sm 2 O 3 , Eu 2 O 3 , La 2 O 3 , Gd 2 O 3 , DY 2 O 3 , Ho 2 O 3 , Er 2 O 3 , Yb 2 O 3 , Y 2 BaCuO 5 , Sm 2 BaCuO 5 , Eu 2 BaCuO 5 , Gd 2 BaCuO 5 , DY 2 BaCuO 5 , Ho 2 BaCuO 5 , Er 2 BaCuO 5 and Yb 2 BaCuO 5 .
Claim 5
Dependent Claim
33 words
A method according to claim 1, wherein said nucleates are selected from the group consisting of CeO 2 , ZrO 2 , BaSnO 3 , BaZrO 3 , MgO, and SrTiO 3 .
Claim 6
Dependent Claim
23 words
A method according to claim 1, wherein said nucleates are selected from the group consisting of Pt, Pd, Rh, Ir, Os, and Ru.
Claim 7
Dependent Claim
16 words
A method according to claim 1, wherein the nucleates used are a powder or single crystal.
Claim 8
Dependent Claim
18 words
A method according to claim 1, wherein platinum or platinum compound powders are added to said pulverized powders.
Claim 9
Dependent Claim
27 words
A method according to claim 7, wherein said platinum or platinum compound powders are added in an amount of 0.1 to 2% by weight, calculated as platinum.
Claim 10
Dependent Claim
42 words
A method according to claim 1, wherein said shaping is carried out after silver or silver oxide powders have been added to and mixed with said pulverized powders in an amount of 1 to 25% by weight of said raw material mixture.
Claim 11
Dependent Claim
42 words
A method according to claim 1, wherein said slow cooling starts from a temperature somewhat higher than the temperature at which a superconducting phase forms from RE 2 BaCuO 5 and liquid phases that coexist at a time of the partial melting.
Claim 12
Dependent Claim
22 words
A method according to claim 1, wherein a temperature for the partial melting of said shape ranges from 950 to 1,250° C.
Claim 13
Dependent Claim
21 words
A method according to claim 1, wherein a rate of said slow cooling ranges from 0.2° to 20° C. per hour.
Claim 14
Dependent Claim
23 words
A method according to claim 1, wherein a temperature for the partial melting of said starting feed ranges from 950° to 1,500° C.
Claim 15
Dependent Claim
27 words
A method according to claim 1, wherein the starting feed is cooled at a rate that equals or exceeds that of air cooling after the partial melting.
Claim 16
Dependent Claim
43 words
A method according to claim 1, wherein said slow cooling takes place with a temperature gradient of 1° C./cm or more around a location of the shape where the nucleants are located so that the temperature of said location is at a low.
Claim 17
Dependent Claim
63 words
A method according to claim 1, wherein a buffer is located between the shape and a table on which the shape is placed at the step of forming the superconducting phase after the shaping, said buffer having a bulk or shape comprising an RE element that is lower than said shape in terms of the temperature at which the superconducting phase starts to.
Claim 18
Dependent Claim
17 words
A method according to claim 16, wherein the table used is well wettable by said liquid phase.
Claim 19
Dependent Claim
67 words
A method according to claim 1, wherein after the superconducting phase has been grown by said slow cooling, it is retained in a temperature range of 650° to 300° C. for 2 to 500 hours in an oxygen-enriched atmosphere, or it is cooled from a high of 650° C. to a low of 300° C. over 2 to 500 hours, thereby adding oxygen to the superconducting phase.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1998-12-11 | 1999-06-12 | 1999-12-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-12-11 | 2003-06-12 | 2003-12-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-12-11 | 2007-06-12 | 2007-12-12 | $7700.00 | Window Closed / Lapsed |