Copper-based high-temperature superconducting material

Details Copper-based high-temperature superconducting material Copper-based high-temperature superconducting material

1999-09-13

2001-10-09

Kopec, Mark (Department: 1751)

Superconductor technology: apparatus, material, process

High temperature , per se

Copper containing

C505S120000, C505S121000

Reexamination Certificate

active

06300284

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a copper-based high-temperature superconducting material in which the critical current density (Jc) and irreversible field (Hirr) are improved without a major decrease in the high superconducting transition temperature (Tc).
2. Description of the Prior Art
In conventional superconductors having a layered structure such as, for example, Y, Bi, Tl, and Hg based copper-oxide superconductors, as shown in
FIG. 2
, because overdoping was used to produce a major decrease in the Tc, even if the superconducting anisotropy &ggr; &ggr; being the coherence length ratio, defined as &xgr;ab/&xgr;c) was decreased, in overall terms there was no improvement in the superconducting characteristics. As a result, at 77 K, it has not been possible to achieve a high Jc and a high Hirr under a high magnetic field condition, which made it difficult to practically apply the superconducting material as wire, in bulk form or as a device material.
With previous high-temperature superconductors having a layered structure, it was difficult to adequately increase the carrier concentration and maintain a high Tc in the overdoped region with the somewhat increased carrier concentration, particularly impossible to achieve a high Jc and a high Hirr under a high magnetic field condition, posing problems with respect to the practical use of the superconducting material as wire, in bulk form or as a device material.
Thus, an object of the present invention is to provide an overdoped high-temperature superconducting material having a high superconducting transition temperature Tc, a high critical current density Jc and a high irreversible field Hirr.
SUMMARY OF THE INVENTION
In order to resolve the above problems, the copper oxide based superconducting material according to the present invention incorporates sufficient oxygen in the carrier supply layer or incorporates cations able to supply holes to thereby effect overdoping of carriers. And, the electron structure (band structure) is utilized for selective doping to overdope part of the CuO
2
plane and maintain the remaining CuO
2
plane in an optimally doped condition, whereby in overall terms a high superconducting transition temperature Tc is maintained at or over 116 K. The critical current density Jc and irreversible field Hirr can be enhanced to not less than 5×10
6
A/cm
2
and to not less than 7 T, respectively, by increasing this carrier concentration.
Further features of the invention, its nature and various advantages will be more apparent from the accompanying drawings and following detailed description of the invention.


REFERENCES:
patent: 5906965 (1999-05-01), Rao
patent: 5919735 (1999-07-01), Ihara et al.
patent: 7-118014 (1995-05-01), None
Ihara et al. “Ca1−xTlxBa2Ca3Ca4O12−y(Cu1−xTlx−1234) Superconductor with Tc2126K” International Conf. on Materials & Mech. of Supercon. High Temp Superconductors, Oct. 1997.*
Ihara et al “New High-Tc Superconductor Ag1−xCuxBa2Can−1CunO2n+3−&dgr;”JJAPvol. 33 (1994) pp. L300-L303, Part 2, No. 3A, Mar. 1994.*
H. Yamauchi, et al., International Symposium of Processing & Critical Current of High Temperature Superconductors, Symposium Handbook, Held at Charles Sturt University, pp. 21, “Realization of Strongly Over-Doped States in M-1223 [M=Hg (Cu,C)] Superconducting Cuprates”, Feb. 2-4, 1998 Abstract.
H. Yamauchi, et al., Institute of Physics Publishing, Superconductor Science and Technology, vol. 11, No. 10, pp. 1006-1010, “Strongly Overdoped States and Irreversibility-Field Characteristics of the Hg-1223 and Cu-1223:P Superconducting Cuprates”, Oct. 1998.
T. Ito, et al., Physica C, vol. 308, No. 1&2, pp. 9-15, “Optimization of the Synthesis and Tuning the Oxygen Content of the CuBa2Ca2Cu3O8+&dgr;(Cu-1223:P) Superconductor”, Nov. 1, 1998.
H. Ihara, et al., Physica C, vol. 282-287, part IV, pp. 1973-1974, “How to Make Superconducting-Anisotropy Least in High-Tc Cuprate Superconductors”, Aug. 1997.

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