US 4,959,346 AGrant
Composite With Y-Ba-Cu-O Superconductive Film
Issue Date:1990-09-25
•21 Claims
Abstract
A composite is produced comprised of Y--Ba--Cu--O superconductive film having a zero resistance transition temperature of at least about 38 K, a zirconium dioxide film and a substrate wherein the zirconium dioxide film is intermediate the superconductive film and the substrate.
Metadata
Assignee
- General Electric Company
Inventors
- Antonio Mogro-Campero
- Larry G. Turner
Application Information
Application Number:US 3545695
Filing Date:1989-05-22
Priority Date:1988-05-09
Art Unit:158
Classifications
IPC:
B32B 900
Field of Search:
5054281;701-704209;426;432;433;688;698-701;930;446;447;901
Patent Drawings
This patent does not have any drawings.
Description
Example 1
The substrate was oxidized silicon.
ZrO.sub.2, Y, Ba, and Cu were used as evaporation sources.
The chamber was evacuated to produce an evacuated chamber with a residual pressure no greater than about 10.sup.-5 torr and such residual pressure was maintained throughout all of the vapor depositions.
The zirconium dioxide was evaporated onto the substrate to produce a film with a thickness of about 0.4 microns. The film covered the entire face of the substrate and from other work it was known that it was microscopically pore-free.
Sequential layers of Cu, Ba and Y of 21.4, 77 and 20 nanometers thickness, respectively, were evaporated on the zirconium dioxide film and this sequence of metals was repeated six times to form an 18-layer stack with a total thickness of 0.6 micron. The 18-layer stack of another specimen prepared simultaneously in the same manner was determined to have the overall composition of YBa.sub.1.9 Cu.sub.3.5.
The resulting structure was annealed immediately after deposition in an oxygen ambient at atmospheric pressure at 800.degree. C. for five minutes and cooled at 2.degree. C. per minute.
The superconductive film had a zero resistance transition temperature of 38 K. The presence of the orthorhombic structure was inferred from resistance measurements. The superconductive film was comprised of a single layer which was continuous, appeared to be pore-free, and had a thickness of about 0.6 microns.
Further annealing for five minutes at 850.degree. C. and cooling at the same rate increased the transition temperature to 47 K.
Example 2
This example was carried out in substantially the same manner as Example 1 except as noted herein.
Barium fluoride was used instead of barium as the evaporation source. A controlled leak of oxygen was introduced into the chamber, which raised the residual pressure to about 10.sup.-5 torr.
Before annealing, the 18-layer stack of another specimen prepared simultaneously in the same manner was determined to have the overall composition of YBa.sub.1.8 Cu.sub.3.0.
The annealing atmosphere was at about atmospheric pressure. It was comprised of oxygen until the annealing temperature of 850.degree. C. was reached. Wet oxygen was then introduced, i.e. oxygen which had been saturated with water at room temperature, and the specimen was annealed in the wet atmosphere at 850.degree. C. for 3.5 hours. It was then cooled only in oxygen at a rate of about 5.degree. C. per minute to about 550.degree. C. where it was held for about 30 minutes and then cooled to room temperature at about 2.degree. C. per minute.
The superconductive film had a zero resistance transition temperature of 83 K. The presence of the orthorhombic crystal structure was inferred from resistance measurements. The superconductive film was comprised of a single layer which was continuous, appeared to be essentially pore-free, and had a thickness of about 0.5 microns.
An elemental depth profile by x-ray photoelectron spectroscopy of another specimen prepared simultaneously in the same manner showed no interdiffusion between the superconductive film and the substrate, and the superconductive film contained about 4 atomic % fluorine throughout the film thickness.
Claims
What is claimed is:
1. A composite consisting essentially of a crystalline superconductive film, a microscopically pore-free zirconium dioxide film and a substrate, said superconductive film having a composition represented by the formula YBa.sub.x Cu.sub.y O.sub.z where x ranges from about 1.7 to about 2.3, where y ranges from about 2.7 to about 3.3 and where z ranges from about 6.5 to about 7.0, said superconductive film having a zero resistance transition temperature of at least about 38 K and a thickness at least sufficient to be continuous ranging from about 0.3 micron to about 1 micron, said substrate being selected from the group consisting of monocrystalline elemental silicon, polycrystalline elemental silicon, oxidized monocrystalline elemental silicon, oxidized polycrystalline element silicon, amorphous silicon dioxide, monocrystalline aluminum oxide and polycrystalline aluminum oxide, said zirconium dioxide film being intermediate said superconductive film and said substrate, said zirconium dioxide film having a thickness ranging from about 2000 Angstroms to about 4000 Angstroms.
2. The composite according to claim 1 wherein said substrate is monocrystalline elemental silicon.
3. The composite according to claim 1 wherein said superconductive film contains fluorine ranging from about 1 to about 7 atomic %.
4. The composite according to claim 1 wherein said superconductive film has a thickness ranging from about 0.4 micron to about 0.5 micron.
5. The composite according to claim 1, wherein said substrate has a thickness ranging from about 300 microns to about 500 microns.
6. The composite according to claim 1, wherein said substrate is polycrystalline elemental silicon.
7. The composite according to claim 1, wherein said substrate is oxidized monocrystalline elemental silicon.
8. The composite according to claim 1, wherein said substrate is oxidized polycrystalline elemental silicon.
9. The composite according to claim 1, wherein said substrate is amorphous silicon dioxide.
10. The composite according to claim 1, wherein said substrate is monocrystalline aluminum oxide.
11. The composite according to claim 1, wherein said substrate is polycrystalline aluminum oxide.
12. A composite consisting essentially of a crystalline superconductive film, a microscopically pore-free zirconium dioxide film and a substrate, said superconductive film having a composition represented by the formula YBa.sub.x Cu.sub.y O.sub.z, where x ranges from about 1.9 to about 2.1, where y ranges from about 2.9 to about 3.1, and where z ranges from about 6.9 to about 7.0, said superconductive film having a zero resistance transition temperature of at least about 38 K and a thickness at least sufficient to be continuous ranging from about 0.4 micron to about 0.5 micron, said substrate being selected from the group consisting of monocrystalline elemental silicon, polycrystalline elemental silicon, oxidized monocrystalline element silicon, oxidized polycrystalline elemental silicon, amorphous silicon dioxide, monocrystalline aluminum oxide and polycrystalline aluminum oxide, said zirconium dioxide film being intermediate said superconductive film and said substrate, said zirconium dioxide film having a thickness ranging from about 2000 Angstroms to about 4000 Angstroms.
13. The composite according to claim 12, wherein said substrate is monocrystalline elemental silicon.
14. The composite according to claim 12, wherein said superconductive film contains fluorine ranging from about 1 to about 7 atomic %.
15. The composite according to claim 12, wherein said substrate has a thickness ranging from about 300 microns to about 500 microns.
16. The composite according to claim 12, wherein said substrate is polycrystalline elemental silicon.
17. The composite according to claim 12, wherein said substrate is oxidized monocrystalline element silicon.
18. The composite according to claim 12, wherein said substrate is oxidized polycrystalline elemental silicon.
19. The composite according to claim 12, wherein said substrate is amorphous silicon dioxide.
20. The composite according to claim 12, wherein said substrate is monocrystalline aluminum oxide.
21. The composite according to claim 12, wherein said substrate is polycrystalline aluminum oxide.
Patent Citations (1)
| Patent | Date | Inventor | Cited By |
|---|---|---|---|
| US4882312 | 1989-11-01 | Mogro-Campero et al. |
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