# US 5,344,816 A · Stable high oxidation state superconducting oxides

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 5,344,816 A
- Document ID: US5344816A
- Status: Granted
- Kind: A
- Application number: 08/023,749
- Filed: 1993-02-24
- Granted: 1994-09-06
- Earliest claimed: 1991-10-23
- Assignees: Hughes Aircraft Company
- Inventors: Ricardo C. Pastor; Antonio C. Pastor, deceased; Luisa E. Gorre, deceased; Keith C. Fuller
- Web page: https://patentgrep.com/patent/US5344816A

## CPC

- H10N 60/0661: {Processes performed after copper oxide formation, e.g. patterning}
- C04B 35/45: based on copper oxide or solid solutions thereof with other oxides
- C04B 35/64: Burning or sintering processes (C04B33/32 takes precedence {; powder metallurgy B22F})
- Y10S 505/725: Process of making or treating high tc, above 30 k, superconducting shaped material, article, or device
- Y10S 505/742: Annealing
- H10N: ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- C04B: LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE {(roofing granules E04D7/005)}; CERAMICS (devitrified glass-ceramics C03C10/00); REFRACTORIES; TREATMENT OF NATURAL STONE
- Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS

## Abstract

High temperature superconducting oxide materials can be taken to a higher, but stable, state of oxidation by removing H-impurities, such as OH.sup.-, using I.sub.2 /O.sub.2 mixtures in a reactive atmosphere process. A higher T.sub.c and a narrower .DELTA.T-transition result.

## Claims

### Claim 1

A process for increasing the superconducting transition temperature and narrowing the .DELTA.T-transition in a high critical temperature (T.sub.c) superconducting oxide comprising:
(a) heating a superconducting oxide selected from the group consisting of YBa.sub.2 Cu.sub.3 O.sub.7-x, Bi.sub.4 Ca.sub.3 Sr.sub.3 Cu.sub.4 O.sub.16+x, and La.sub.2 CuO.sub.4, wherein x is the variation in oxygen stoichiometry, to a temperature ranging from about 850.degree. C. to below the melting point of said oxide; and
(b) treating said oxide with a flowing gas reactive mixture consisting of oxygen and iodine at said temperature to increase the oxidation state of said oxide to a higher oxidation state and avoid absorption of iodine by said oxide, said gas reactive mixture comprising about 1 to 5 mm of Hg of iodine and the balance oxygen in a total atmosphere of about one atm.

### Claim 2 (depends on 1)

The process of claim 1 wherein said temperature is less than about 1,100.degree. C.

### Claim 3 (depends on 2)

The process of claim 2 wherein said temperature ranges from about 900.degree. C. to less than about 1,000.degree. C.

### Claim 4 (depends on 1)

The process of claim 1 wherein said oxide is exposed at said temperature for a period of time of at least about 2 hours.

### Claim 5 (depends on 4)

The process of claim 4 wherein said period of time ranges from about 4 to 15 hours.

### Claim 6 (depends on 1)

The process of claim 1 wherein said superconducting oxide is in powder form.

### Claim 7 (depends on 1)

The process of claim 1 wherein said superconducting oxide is in pellet form and said treatment follows a sintering step to form said pellet.

### Claim 8 (depends on 1)

The process of claim 1 wherein said gas mixture is flowed over said superconducting oxide at a rate of about 60 cm.sup.3 /min.

### Claim 9 (depends on 1)

The process of claim 1 wherein said superconducting oxide is in powder form.