US5318745A
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Oxide superconductor and manufacturing method thereof via HIP and controlling the oxygen partial pressure
Assignee: International Superconductivity Technology Center
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Filing: 1991-09-20
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Granted: 1994-06-07
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Expires: 2011-09-20
Abstract
Abstract PCT No. PCT/JP91/01248 Sec. 371 Date Jul. 8, 1992 Sec. 102(e) Date Jul. 8, 1992 PCT Filed Sep. 20, 1991 PCT Pub. No. WO92/05126 PCT Pub. Date Apr. 2, 1992.A method of manufacturing an oxide superconductor having a composition expressed by formula La2-XSrXCaCu2O6 (0<X</=0.6), comprising the steps of: preliminarily burning a raw powder having a predetermined composition, and sintering the powder to obtain a sintered body; and subjecting the sintered body to hot isostatic pressing at a temperature falling within a range of from 940 DEG -1600 DEG C. under total pressure of 10 MPa or more and oxygen partial pressure of 2 MPa or more. By virtue of the step of subjecting the sintered body to hot isostatic pressing, a superconductor can be manufactured at a temperature and under a pressure within respective wide ranges. Further, the composition of the superconductor can be selected within a wide range of 0<X</=0.6. Moreover, the superconductor can be manufactured by performing quenching after the hot isostatic pressing.
Inventors
- 👤 Takeshi Sakurai
- 👤 Toru Yamashita
- 👤 Hisao Yamauchi
- 👤 Shoji Tanaka
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 03:36
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/01; C04B35/45; C04B35/4504; H; H10; H10N; H10N60/00; H10N60/01; H10N60/0268; C04B35/622; C04B35/64; C04B35/645; C04B35/6455; H10N60/0661; H10N60/80; H10N60/85; H10N60/855; H10N60/857; Y; Y10; Y10S; Y10S505/00; Y10S505/725; Y10S505/742
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
163 words
A method of manufacturing an oxide superconductor having a composition of the formula La 2-x Sr X CaCu 2 O 6 wherein 0<x≦0.6, comprising: preliminarily burning a raw powder having a predetermined composition, and sintering the powder at a sintering temperature to obtain a sintered body; and hot isostatic pressing the sintered body at a hot isostatic pressing temperature of 940° to 1220° C., said hot isostatic pressing temperature in an oxygen atmosphere being higher than the sintering temperature, under a total pressure of 10 MPa or more and an oxygen partial pressure of 2 MPa or more controlling a relationship between the total pressure and the oxygen partial pressure such that the oxide superconductor satisfies the following formula: Tc on (R)-Tc on (mag)≧3.0K wherein Tc on (R) is an onset temperature point obtained by measuring electrical resistance at a time of lowering temperature, Tc on (mag) is the superconduction critical temperature obtained by measuring magnetic susceptibility during cooling in a magnetic field.
Claim 2
Independent Claim
163 words
A method of manufacturing an oxide superconductor having a composition of the formula La 2-x Sr X CaCu 2 O 6 wherein 0<x≦0.6, comprising: preliminarily burning a raw powder having a predetermined composition, and sintering the powder at a sintering temperature to obtain a sintered body; and hot isostatic pressing the sintered body at a hot isostatic pressing temperature of 940° to 1220° C., said hot isostatic pressing temperature in an oxygen atmosphere being higher than the sintering temperature, under a total pressure of 10 MPa or more and an oxygen partial pressure of 2 MPa or more controlling a relationship between the total pressure and the oxygen partial pressure such that the oxide superconductor satisfies the following formula: Tc on (R)-Tc on (mag)≧3.0K wherein Tc on (R) is an onset temperature point obtained by measuring electrical resistance at a time of lowering temperature, Tc on (mag) is the superconduction critical temperature obtained by measuring magnetic susceptibility during cooling in a magnetic field.
Claim 3
Dependent Claim
32 words
The method according to claim 1, wherein the hot isostatic pressing is performed at a total pressure of 100 MPa or more and an oxygen partial pressure of 20 MPa or more.
Claim 4
Dependent Claim
30 words
The method according to claim 1, wherein the raw powder is selected from the group consisting of La 2 O 3 , CaCO 3 , SrCO 3 , and CuO.
Claim 5
Dependent Claim
24 words
The method according to claim 1, wherein the preliminary burning is repeated in an oxygen atmosphere at a temperature of 850° to 950° C.
Claim 6
Dependent Claim
22 words
The method according to claim 1, wherein the sintering is performed in a flow of oxygen at a temperature of 925°-1200° C.
Claim 7
Dependent Claim
19 words
The method according to claim 1, wherein the hot isostatic pressing is performed at a temperature of 1070°-1220° C.
Claim 8
Dependent Claim
25 words
The method according to claim 1, further comprising quenching at a cooling rate of 400° C. or more per hour after the hot isostatic pressing.
Claim 9
Dependent Claim
85 words
An oxide superconductor having a composition of the formula La 2-x Sr x CaCu 2 O 6 wherein 0<x≦0.6, wherein Ca≦0.25 and Sr≦0.15 in 2a sites, and La≦0.2 and Sr ≦0.2 in 4e sites, the oxide superconductor satisfying the following formula: Tc on (R)-Tc on (mag)≧3.0K wherein Tc on (R) is an onset temperature point obtained by measuring electrical resistance at a time of lowering temperature, Tc on (mag) is the superconduction critical temperature obtained by measuring magnetic susceptibility during cooling in a magnetic field.
Claim 10
Dependent Claim
85 words
An oxide superconductor having a composition of the formula La 2-x Sr x CaCu 2 O 6 wherein 0<x≦0.6, wherein Ca≦0.25 and Sr≦0.15 in 2a sites, and La≦0.2 and Sr ≦0.2 in 4e sites, the oxide superconductor satisfying the following formula: Tc on (R)-Tc on (mag)≧3.0K wherein Tc on (R) is an onset temperature point obtained by measuring electrical resistance at a time of lowering temperature, Tc on (mag) is the superconduction critical temperature obtained by measuring magnetic susceptibility during cooling in a magnetic field.
Claim 11
Dependent Claim
16 words
The oxide superconductor according to claim 8, having a superconductive critical temperature of 50K or more.
Claim 12
Dependent Claim
55 words
The method according to claim 2, wherein the raw powder comprises La 2 O 3 , CaCO 3 , SrCO 3 and CuO; the preliminary burning is carried out at a temperature of 850° to 950° C. and the sintering is carried out in an oxygen atmosphere at a temperature of 925° to 1200° C.
Claim 13
Dependent Claim
21 words
The method according to claim 10, wherein hot isostatic pressing is carried out at a temperature of 1070° to 1220° C.
Claim 14
Dependent Claim
26 words
The method according to claim 11, which further comprises quenching at a cooling rate of 400° C. or more per hour after the hot isostatic pressuring.
Claim 15
Dependent Claim
64 words
The oxide superconductor according to claim 8 selected from the group consisting of La 2 CaCu 2 O 6 , La 1 .95 Sr 0 .05 CaCu 2 O 6 , La 1 .6 Sr 0 .4 CaCu 2 O 6 , La 1 .4 Sr 0 .6 CaCu 2 O 6 and La 1 .3 Sr 0 .7 CaCu 2 O 6 .
Claim 16
Dependent Claim
23 words
The oxide superconductor according to claim 1, wherein the hot isostatic pressing temperature is at least 40° C. higher than the sintering temperature.
Claim 17
Dependent Claim
23 words
The oxide superconductor according to claim 1, wherein x is 0.4 to 0.6 and the sintering temperature is not less than 950° C.
Claim 18
Dependent Claim
31 words
The oxide superconductor according to claim 1, wherein x is 0.4 to 0.6 and the hot isostatic pressing temperature, Ta, and the sintering temperature, Ts, satisfy the following formula; (Ta-Ts)≦200° C.
Claim 19
Dependent Claim
29 words
The oxide superconductor according to claim 1, wherein x is 0.4 to 0.6 and the hot isostatic pressing temperature in an oxygen atmosphere is not higher than 1200° C.
Claim 20
Dependent Claim
30 words
The oxide superconductor according to claim 1, wherein x is 0.4 and the hot isostatic pressing temperature, Ta, and the sintering temperature, Ts, satisfy the following formula: (Ta-Ts) ≦100° C.
Claim 21
Dependent Claim
24 words
The oxide superconductor according to claim 1, wherein the hot isostatic pressure is carried out at a total pressure of 50 atm or higher.
References Cited (Backward Citations)
JPS63288912A
Cited
JPH01160876A
Cited
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