Superconductor technology: apparatus – material – process – High temperature – per se – Copper containing
Patent
1998-06-03
2000-05-16
Kopec, Mark
Superconductor technology: apparatus, material, process
High temperature , per se
Copper containing
505126, 505500, 505742, 505785, C04B 35505, C04B 3564
Patent
active
060637358
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a superconductor premixture prepared for fusion processing, a method for the production thereof, and a YBa.sub.2 Cu.sub.3 O.sub.7-x powder which can be used in preparing the premixture.
YBa.sub.2 Cu.sub.3 O.sub.7-x powder (x=0 to 0.5) is used for the preparation of technical superconductors. The powder is advantageously mixed with stabilizing additives which form sticking or pinning centers. The resulting premixture is pressed into compacts and heat treated, preferably by fusion processing. In fusion processing the surfaces of the powder particles of the premixture are heat-softened, so that in the cooling that follows the particles are bonded tightly to one another. The flow of the electric current through the grain boundaries is thus improved. The stabilizing additives usually have the effect of reducing the melting temperature of the premixture, so that the softening of the bodies that are to formed and the escape of molten material otherwise observed at higher fusion texturizing temperatures, can be prevented. The additives, which form sticking or pinning centers, permit increasing the critical current density in the superconductors. The pinning centers provide for an anchoring of the magnetic lines of flux, so that high critical currents can also be achieved in the magnetic field. Flux pinning additives for superconductors composes of copper oxide are disclosed, for example, in European Patent Applications EP-A-0 292 126 and 296 380.
The bodies obtained by fusion processing from high-temperature superconductor material can be used, for example, in the manufacture of electric motors and in the production of the so-called "flywheel." The flywheel rotates under superconducting conditions in the magnetic field and serves to store kinetic energy.
SUMMARY OF THE INVENTION
It is the object of the present invention to provide an improved premixture composed of YBa.sub.2 Cu.sub.3 O.sub.7-x powders with stabilizing additives or those producing flux pinning. This object is achieved by the premixture described below.
The invention is based on the knowledge that premixtures which comprise the YBa.sub.2 Cu.sub.3 O.sub.7-x powders and stabilizing or flux pinning additives are especially well suited for the preparation of fusion-processed bodies if they have a small content of carbon combined with a small content of free copper oxide not bound in the YBa.sub.2 Cu.sub.3 O.sub.7-x phase.
The superconductor premixture according to the invention, which is designed for fusion processing, comprises additives which produce flux pinning as well as YBa.sub.2 Cu.sub.3 O.sub.7-x powder, this YBa.sub.2 Cu.sub.3 O.sub.7-x powder containing less than 0.6 wt.-% of free copper oxide not bound in the YBa.sub.2 Cu.sub.3 O.sub.7-x phase and less than 0.1 wt.-% carbon, relative to the YBa.sub.2 Cu.sub.3 O.sub.7-x powder.
The stabilizing or flux pinning additives can basically be added in any amount in which they result in the desired effect. The stabilizing action lies, for example, in the fact that the melting temperature of the particles in the superconductor premixture is lowered. The additives that produce the flux pinning cause the magnetic flux lines to be anchored in the superconducting material, and consequently high critical currents become possible. Any customary stabilizing or flux pinning additives can be used. There are additives, such as Y.sub.2 BaCuO.sub.5, of which it is assumed that they have both a stabilizing and a flux pinning action. Especially well suited as additives are Y.sub.2 O.sub.3, Y.sub.2 BaCuO.sub.5, PtO.sub.2, Ag.sub.2 O, CeO.sub.2, SnO.sub.2, ZrO.sub.2, BaCeO.sub.3 and BaTiO.sub.3.
Preferred superconductor premixtures according to the invention contain 0.1 to 50 wt.-% of stabilizing additives or additives that produce flux pinning, relative to the YBa.sub.2 Cu.sub.3 O.sub.7-x powder taken as 100%.
A content of Y.sub.2 O.sub.3, Y.sub.2 BaCuO.sub.5, PtO.sub.2, Ag.sub.2 O, CeO.sub.2, SnO.sub.2, ZrO.sub.2, BaCeO.sub.3 and/or BaTiO.sub.3 is preferred as
REFERENCES:
patent: 5413981 (1995-05-01), Egawa et al.
Aldrich Chemicals .fwdarw. Products for Superconductivity Research, p. 17, 1991.
Stecura, "Superconducting YBa.sub.2 Cu.sub.3 O.sub.7 Powder . . . " J. Mater. Bynth. Process, 2(3) pp. 169-177 (Abstract Only), 1994.
Osamura et al "Improvement of Critical Current Density in YBa.sub.2 Cu.sub.3 O.sub.7 . . . " JJAP, vol. 29, No. 9, Sep. 1990 pp. L 1621-1623.
Todt et al., "Melt-processing of YBa.sub.2 CU.sub.3 O.sub.x and Bi.sub.2 Sr.sub.2 CaCu.sub.2 O.sub.y : Influence of Processing Parameters on Microstructure and Magnetization Behavior", IEEE Transactions on Applied Superconductivity, vol. 5, No. 2, Jun. 1995, pp. 1623-1626.
Baliga et al., "Enhanced Grain Growth in Yba.sub.2 Cu.sub.3 O.sub.7 Doped with Ag, Cu, and CuO", Applied Physics A: Solids and Surfaces, A49 (Aug. 1989), No. 2, pp. 139-140.
Fischer Klaus
Gawalek Wolfgang
Goernert Peter
Habisreuther Tobias
Hardinghaus Ferdinand
Institut fuer Physikalische Hochtechnologie e.V.
Kopec Mark
Solvay Barium Strontium GmbH
LandOfFree
Superconductor mixture does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Superconductor mixture, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Superconductor mixture will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-258789