Oxide superconductor and method for manufacturing the same

A method for manufacturing an oxide superconductor comprising:

• heating raw materials of an oxide superconductor at a temperature of 800.degree. to 1200.degree. C. under a superhigh pressure of 2 to 8 GPa;
• to prepare an oxide superconductor comprising a composition of the formula:
• (Pb.sub.1-x-y M.sub.x (A1).sub.y)(A2).sub.2 (A3).sub.n-1 (Cu).sub.n (O).sub.2n+3+z
• wherein
• 0.ltoreq.x.ltoreq.0.6,
• 0.ltoreq.y.ltoreq.0.6,
• x+y.ltoreq.0.6,
• n is an integer of 3 or 4,
• -0.6.ltoreq.z.ltoreq.0.5
• M is Cu or Cd and
• A1, A2 and A3 are each independently one element selected from the group consisting of Ba, Sr and Ca,
• the oxide superconductor having a crystal structure comprising stacked layers in the following order:
• a first rock salt structure portion, an infinite layer structure stacked on the first rock salt structure portion and a second rock salt structure portion stacked on the infinite layer structure, the first rock salt structure portion and the second rock salt structure portion each comprising a (Pb, M, A1)-oxygen layer stacked on an A2-oxygen layer, said (Pb, M, A1)-oxygen layer having a ratio of the total number of atoms of Pb, M and A1 to the number of oxygen atoms of 1:0.5 to 1.5, said A2-oxygen layer having a ratio of the number of A2 atoms to the number of oxygen atoms of 1:1 or less, the infinite layer structure comprising a Cu-oxygen layer stacked on a layer of A3, the Cu-oxygen layer having a ratio of the number of copper atoms to the number of oxygen atoms of 1:2.

An oxide superconductor comprising a composition of the formula:

• (Pb.sub.1-x-y M.sub.x (A1).sub.y)(A2).sub.2 (A3).sub.n-1 (Cu).sub.n (O).sub.2n+3+z
• wherein
• 0.ltoreq.x.ltoreq.0.6,
• 0.ltoreq.y.ltoreq.0.6,
• x+y.ltoreq.0.6,
• n is an integer of 3 or 4,
• -0.6.ltoreq.z.ltoreq.0.5,
• M is Cd and x is defined as follows:
• 0.1.ltoreq.x.ltoreq.0.6,
• A1, A2 and A3 are each independently one element selected from the group consisting of Ba, Sr and Ca,
• the oxide superconductor having a crystal structure comprising stacked layers in the following order:
• a first rock salt structure portion, an infinite layer structure stacked on the first rock salt structure portion and a second rock salt structure portion stacked on the infinite layer structure, the first rock salt structure portion and the second rock salt structure portion each comprising a (Pb, M, A1)-oxygen layer stacked on an A2-oxygen layer, said (Pb, M, A1)-oxygen layer having a ratio of the total number of atoms of Pb, M and A1 to the number of oxygen atoms of 1:0.5 to 1.5, said A2-oxygen layer having a ratio of the number of A2 atoms to the number of oxygen atoms of 1:1 or less, the infinite layer structure comprising a Cu-oxygen layer stacked on a layer of A3, the Cu-oxygen layer having a ratio of the number of copper atoms to the number of oxygen atoms of 1:2.