Abstract: Provided is an Hg--Ba--Ca--Cu--O oxide superconductor having a high superconductivity transition temperature Tc and a method which can prepare the same in excellent reproducibility. This oxide superconductor consists essentially of Hg, Ba, Ca, Cu and O, and is expressed in a chemical formula (Hg.sub.1-X Cu.sub.X)Ba.sub.2 Ca.sub.2 Cu.sub.3 O.sub.y, wherein X=0.05 to 0.7 and Y=8 to 8.75. A method of preparing the oxide superconductor comprises a step of mixing raw materials of Hg, Ba, Ca and Cu with each other so that (Hg+Ba):Ca:Cu =b:1:C and Hg:Ba=(1-a):a, wherein 0.625.ltoreq.a.ltoreq.0.714, 1.ltoreq.b.ltoreq.3 and 1.667.ltoreq.c.ltoreq.3.444, in mole ratio, and compression-molding the mixture, and a step of heat treating a compact obtained by the compression molding. This oxide superconductor has a superconductivity transition temperature Tc of 134 K, which is the highest at present.

Abstract: Provided is an Hg-Ba-Ca-Cu-O oxide superconductor having a high superconductivity transition temperature Tc and a method which can prepare the same in excellent reproducibility. This oxide superconductor consists essentially of Hg, Ba, Ca, Cu and O, and is expressed in a chemical formula (Hg.sub.1-X Cu.sub.X)Ba.sub.2 Ca.sub.2 Cu.sub.3 O.sub.Y, wherein X=0.05 to 0.7 and Y=8 to 8.75. A method of preparing the oxide superconductor comprises a step of mixing raw materials of Hg, Ba, Ca and Cu with each other so that (Hg+Ba):Ca:Cu=b:1:C and Hg:Ba=(1-a):a, wherein 0.625.ltoreq.a.ltoreq.0.714, 1.ltoreq.b.ltoreq.3 and 1.667.ltoreq.c.ltoreq.3.444, in mole ratio, and compression-molding the mixture, and a step of heat treating a compact obtained by the compression molding. This oxide superconductor has a superconductivity transition temperature Tc of 134 K., which is the highest at present.

Abstract: The oxide superconductor according to the present invention is represented by (Hg.sub.1-x Pb.sub.x)Ba.sub.2 Ca.sub.2 Cu.sub.3 O.sub..delta. (0.08.ltoreq.x.ltoreq.0.41, 7.625.ltoreq..delta..ltoreq.9.15), and has a crystal structure in which a lamination unit of (Hg, Pb)O.sub.z -BaO-CuO.sub.2 -Ca-CuO.sub.2 -Ca-CuO.sub.2 -BaO is laminated in a c-axial direction of the crystal structure (0.625.ltoreq.z.ltoreq.2.15). Further, the method of manufacturing an oxide superconductor, according to the present invention, includes the steps of: mixing material powders of HgO, PbO, BaO, CaO and CuO at a mole ratio of (Hg.sub.1-x Pb.sub.x):Ba:Ca:Cu=a:2:b:c (1.ltoreq.a.ltoreq.2.5, 2.ltoreq.b.ltoreq.3, 2.5.ltoreq.c.ltoreq.4) and compression-molding the mixture powder into a compact; and subjecting the compact to a thermal treatment at 600.degree.-750.degree. C.