An oxide superconductor of an embodiment includes an oxide superconductor layer having a continuous Perovskite structure containing rare earth elements, barium (Ba), and copper (Cu). The rare earth elements contain a first element which is praseodymium (Pr), at least one second element selected from the group consisting of neodymium (Nd), samarium (Sm), europium (Eu), and gadolinium (Gd), at least one third element selected from the group consisting of yttrium (Y), terbium (Tb), dysprosium (Dy), and holmium (Ho), and at least one fourth element selected from the group consisting of erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu).

An oxide superconductor of an embodiment includes an oxide superconducting layer including a first superconducting region containing barium, copper, and a first rare earth element, having a continuous perovskite structure, and extending in a first direction, a second superconducting region containing barium, copper, and a second rare earth element, having a continuous perovskite structure, and extending in the first direction, and a non-superconducting region disposed between the first and the second superconducting region, containing praseodymium, barium, copper, and a third rare earth element, a ratio of the number of atoms of the praseodymium to a sum of the number of atoms of the third rare earth element and the number of atoms of the praseodymium which is 20% or more, having a continuous perovskite structure continuous with the perovskite structure of the first superconducting region and the perovskite structure of the second superconducting region, and extending in the first direction.

A process for producing a cube textured foil is described. The process includes providing a cube textured metal foil M. The process further includes electroplating an epitaxial layer of an alloy on the foil M, whereby the epitaxial layer substantially replicates the cube texture of the metal foil M. The process further includes electroplating a non-epitaxial layer of an alloy on the epitaxial layer. The process further includes separating the electroplated alloy from the cube textured metal foil M to obtain an electro-formed alloy with one cube textured surface.

An oxide superconductor of an embodiment includes an oxide superconducting layer including at least one superconducting region containing barium (Ba), copper (Cu), and a first rare earth element, having a continuous perovskite structure, and having a size of 100 nm100 nm100 nm or more, and a non-superconducting region in contact with the at least one superconducting region, containing praseodymium (Pr), barium (Ba), copper (Cu), and a second rare earth element, having a ratio of a number of atoms of the praseodymium (Pr) to a sum of a number of atoms of the second rare earth element and the number of atoms of the praseodymium (Pr) being 20% or more, having a continuous perovskite structure continuous with the continuous perovskite structure of the superconducting region, and having a size of 100 nm100 nm100 nm or more.

An oxide superconductor of an embodiment includes an oxide superconducting layer including a first superconducting region containing barium, copper, and a first rare earth element, having a continuous perovskite structure, and extending in a first direction, a second superconducting region containing barium, copper, and a second rare earth element, haying a continuous perovskite structure, and extending in the first direction, and a non-superconducting region disposed between the first and the second superconducting region, containing praseodymium, barium, copper, and a third rare earth element, a ratio of the number of atoms of the praseodymium to a sum of the number of atoms of the third rare earth element and the number of atoms of the praseodymium which is 20% or more, having a continuous perovskite structure continuous with the perovskite structure of the first superconducting region and the perovskite structure of the second superconducting region, and extending in the first direction.

The superconductive wire includes a superconductive layer containing REBa.sub.2Cu.sub.3O.sub.x. RE represents a rare earth element. The superconductive layer contains halogen. The concentration of halogen in the superconductive layer is less than 2000 ppm by mass.