R-Ce-Cu-O superconducting oxide material wherein R is at least o

Details R-Ce-Cu-O superconducting oxide material wherein R is at least o R-Ce-Cu-O superconducting oxide material wherein R is at least o

1990-01-25

1992-09-01

Lieberman, Paul

Superconductor technology: apparatus, material, process

High temperature , per se

Having tc greater than or equal to 150 k

252518, 252521, 505779, C01F 1700, C01G 302, H01L 3912

Patent

active

051438950

ABSTRACT:
The disclosed superconducting oxide material has a crystal structure of either Nd.sub.2 CuO.sub.4 type or oxygen-deficient perovskite type and mainly consists of a composition having a general chemical formula of (R.sub.1-x A.sub.x).sub.m+1 Cu.sub.m O.sub.3m+1-y, R being at least one rare earth element selected from the group consisting of Pr, Nd, Sm, Eu, Gd, Dy, Tb, Ho, Er, Tm, Yb, and Lu, A being Ce or Th, m being an integer of 1, 2, 3, . . . .infin. (m=.infin. standing for (R.sub.1-x A.sub.x)CuO.sub.3-y), 0.ltoreq.x.ltoreq.1, 0.ltoreq.y.ltoreq.m, Cu in the material having an average valence of not larger than +2 for all R, A, m, x, and y.
The disclosed superconducting oxide material may have a general chemical formula of Nd.sub.2-x-z Ce.sub.x Sr.sub.z CuO.sub.4-y, 0.ltoreq.x.ltoreq.1, 0.ltoreq.y.ltoreq.1, and 0.ltoreq.z.ltoreq.1.
The above superconducting oxide material can be made by mixing powdery starting materials for the composition, sintering the mixture at 1,000.degree. to 1,100.degree. C. in air, and heat treating the sintered mixture at 900.degree. to 1,100.degree. C. in a reducing atmosphere (with an oxygen partial pressure of less than 10.sup.-2 atm.)

REFERENCES:
Tokura et al., "A Superconducting Copper Oxide Compound with Electrons as the Charge Carriers," Nature vol. 337, Jan. 26, 1989.
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Izumi et al., "Crystal Structure of the Superconductor Ba.sub.1.8 Nd.sub.1.2 Cu.sub.3 O.sub.7 " Jap. Jnl. Appl. Phys. v. 26(10) Oct. 1987, pp. L1616-L1619.
N. Takagi et al., "Superconductivity Produced by Electron Doping in CuO.sub.2 -Layered Compounds", Physical Review Letters, vol. 62, No. 10, Mar. 6, 1989, pp. 1197-1200.
H. Takagi et al., "Electron-Doped Superconductivity in CuO.sub.2 Layered Compounds with Nd.sub.2 CuO.sub.4 -structure", Mat. Res. Soc. Symp. Proc., vol. 156, 1989, pp. 389-395.
A. Khurana, "Electron Superconductors Challenge Theories, Start a New Race" Physics Today, Apr., 1989, pp. 17-19.

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