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 includes: REBa.sub.2Cu.sub.3O.sub.7-x (RE being one element selected from a RE element group of Pr, Nd, Sm, Eu, Gd, Y, Tb, Dy, Ho, Er, Tm, Yb, and Lu). The RE includes at least three, types of metallic elements (M1, M2, and M3), and the three types of metallic elements are any element of the RE element group selected in order. In an oxide system satisfying R(1)20 mol % and R(M2)60 mol % and R(M3)20 mol %, R(M1) being an average metallic element ratio of M1 in M1+M2+M3, SD(Ms)>0.15 is satisfied at a position at 50% of an average film thickness of a cross section including the c-axis, Ms being the metallic element of not larger of R(M1) and R(M3), SD(Ms) being a standard deviation/average value of a concentration of Ms.

An oxide superconductor of an embodiment includes an oxide superconductor layer having a continuous Perovskite structure including rare earth elements, barium (Ba), and copper (Cu). The rare earth elements include a first element which is praseodymium, at least one second element selected from the group consisting of neodymium, samarium, europium, and gadolinium, at least one third element selected from the group consisting of yttrium, terbium, dysprosium, and holmium, and at least one fourth element selected from the group consisting of erbium, thulium, ytterbium, and lutetium. When the number of atoms of the first element is N(PA), the number of atoms of the second element is N(SA), and the number of atoms of the fourth element is N(CA), 1.5(N(PA)+N(SA))N(CA) or 2(N(CA)N(PA))N(SA) is satisfied.

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).

According to an embodiment, a superconductor includes a base member, and a superconducting layer provided on the base member. The superconducting layer has a first surface on the base member side, and a second surface on the side opposite to the first surface. The lattice constant of the base member substantially matches the lattice constant of the superconducting layer. The superconducting layer includes REA.sub.1-xREB.sub.xBa.sub.2Cu.sub.3O.sub.7-z. The x is not less than 0.01 and not more than 0.40. The z is not less than 0.02 and not more than 0.20. The REA includes at least one of Y, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, or Lu. The REB includes at least one of Nd or Sm. The superconducting layer includes a first surface-side region including a portion of the first surface. The first surface-side region includes a first region having an orientation property, and a second region.

A superconducting coil of an embodiment includes a superconducting wire including an oxide superconductor layer. The oxide superconductor layer has a continuous Perovskite structure including rare earth elements, barium (Ba), and copper (Cu). The rare earth elements include 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).

A superconducting layer joint structure of embodiments includes: a first superconducting layer; a second superconducting layer; and a joint layer provided between the first superconducting layer and the second superconducting layer and containing a plurality of crystal particles containing a rare earth element (RE), barium (Ba), copper (Cu), and oxygen (O). The plurality of crystal particles includes at least one first particle. The at least one first particle has a first inner region and a first outer region. The first inner region is disposed inside the first superconducting layer. The first outer region is disposed outside the first superconducting layer.

An oxide superconducting thin film material includes: a metal substrate having a surface with a biaxially oriented crystal orientation structure; an intermediate layer biaxially oriented and formed on the metal substrate; and an oxide superconducting thin film formed on the intermediate layer and composed of a RE123-based oxide superconductor represented by REBa.sub.2Cu.sub.3O.sub.y. The oxide superconducting thin film includes Br (bromine).

The present invention is in the field of nanoparticles, their preparation and their use as pinning centers in superconductors. In particular the present invention relates to nanoparticles comprising an oxide of Sr, Ba, Y, La, Ti, Zr, Hf, Nb, or Ta, wherein the nanoparticles have a weight average diameter of 1 to 30 nm and wherein an organic compound of general formula (I), (II) or (III) or an organic compound containing at least two carboxylic acid groups on the surface of the nanoparticles (I) (II) (III) wherein a is 0 to 5, b and c are independent of each other 1 to 14, n is 1 to 5, f is 0 to 5, p and q are independent of each other 1 to 14, and e and f are independent of each other 0 to 12. ##STR00001##

According to an embodiment, a superconductor includes a base member, and a superconducting layer provided on the base member. The superconducting Layer has a first surface on the base member side, and a second surface on the side opposite to the first surface. The lattice constant of the base member substantially matches the lattice constant of the superconducting layer. The superconducting layer includes REA.sub.1-xREB.sub.xBa.sub.2Cu.sub.3O.sub.7-z. The x is not less than 0.01 and not more than 0.40. The z is not less than 0.02 and not more than 0.20. The REA includes at least one of Y, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, or Lu. The REB includes at least one of Nd or Sm. The superconducting layer includes a first surface-side region including a portion of the first surface. The first surface-side region includes a first region having an orientation property, and a second region.