Superconducting material

#1. Field of the Invention

#The present invention relates to an oxide ceramic superconducting material, and more particularly to a composition wherein the temperature of a superconducting material at which electrical resistance becomes zero (which is referred to as Tco hereinafter) approaches a room temperature as much as possible.

#2. Background of the Invention

#These and other objects, features, and advantages of the present invention will become more apparent from the following description of the preferred embodiments taken in conjunction with the accompanying drawings, in which:

#FIG. 1 is a graph showing the characteristics of the superconducting material made according to the present invention.

#To satisfy these objects of the present invention, a ceramic superconducting material is made to essentially consist copper, oxygen and at least one element selected from the group of Groups 11a and 111a of the Periodic Table. One example of a general formula representing the molecule of this ceramic superconducting material is (A.sub.1-x B.sub.x).sub.y Cu.sub.z O.sub.w, where x=0 to 1, y=2.0 to 4.0 or preferably 2.5 to 3.5, z=1.0 to 4.0 or preferably 1.5 to 3.5, and w=4.0 to 10.0 or preferably 6 to 8. A is one element selected from the group of the yttrium group and other lanthanides. The yttrium group is defined in "Physic and Chemistry Dictionary" (published Apr. 1, 1963, Iwanami Shoten) as the group includes Y(yttrium), Gd(gadolinium), Yb(ytterbium), Eu(europium), Tb(terbium), Dy(dysprosium), Ho(holnium), Er(erbium), Tm(thulium), Lu(lutetium), Sc(scandium), and other lanthanides. Also, B is at least one element selected from the group of Ra(radium), Ba(barium), Sr(strontium), Ca(calcium), Mg(magnesium), and Be(beryllium).

#The composition of the present invention contains copper in a layered configuration, with one layer within one unit cell, or in a symmetric two-layer structure, and is based on a model in which superconductivity is obtained from the orbit of the furthest exterior nucleus electron.

#For this reason, raw materials of 99.99% (4N) purity or higher are used rather than the conventionally-used 99(2N) to 99. 95% purity as a starting material. Then, an oxygen atmosphere of a purity in excess of 4N is used rather than air for oxidation, and the material is fired in 5N oxygen and 5N argon, or under vacuum for reduction.