According to the present invention, a piezoelectric film having a single crystal structure is able to be formed, from various piezoelectric materials, on a film structure of the present invention. A film structure according to the present invention includes: a substrate; a buffer film which is formed on the substrate and has a tetragonal crystal structure containing zirconia; a metal film containing a platinum group element, which is formed on the buffer film by means of epitaxial growth; and a film containing Sr(Ti.sub.1−x, Ru.sub.x)O.sub.3 (wherein 0≤x≤1), which is formed on the metal film by means of epitaxial growth.

A superconductor wire can achieve a J.sub.e of at least 600 A/mm.sup.2 at 4.2 K, 20 T applied magnetic field, which is greater than J.sub.e previously reported in the literature. The superconductor wire can include superconductor tape stands that have I.sub.c per total strand width of at least 125 A/mm at 4.2 K, 20 T applied magnetic field. In an embodiment, the superconductor wire can have superconductor film with a modified REBCO composition, where (Ba+M)/Cu is at least 0.72. In the same or different embodiment, the superconductor film can have a thickness of at least 3 microns. The superconductor tape strands can have a stabilizer layer, where the thickness of the stabilizer is selected so that the neutral plane of the strands is near or passes through the superconductor film. A superconductor cable can be made from superconductor wires.

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).

Methods and devices for producing a superconductive conductor are disclosed. The method includes providing a plurality of conductive strips by means of a strip provision device, applying liquid soldering agent onto the plurality of conductive strips, stacking the conductive strips wetted with soldering agent, and forming a superconductive body by machining the strip stack.

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.

Provided is a superconducting wire. The superconducting wire comprises a substrate, a superconducting film on the substrate and a pinning center in the superconducting film. The superconducting film includes Y.sub.1-xRE.sub.xBCO and the pinning center has an additive of Ba.sub.2YNbO.sub.6.

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.

The invention relates to a (RE,Y)-123 superconducting film containing mixed artificial pinning centers and a preparation method thereof, wherein a stoichiometric ratio of Cu in a parent phase of the (RE,Y)-123 superconducting film is 3.05-5; the mixed artificial pinning centers include a perovskite structure BaMO3 and a double-perovskite structure oxide Ba2(RE,Y)NO6; and a total mole percentage of Ba2(RE,Y)NO6 in the superconducting film is not less than 2.5%. The mixed artificial pinning centers form well-aligned column structures along the thickness direction in the superconducting film. The invention is intended not only to solve the problem that a single secondary phase cannot be well aligned along the thickness direction of (RE,Y)-123 when using the high-speed pulsed laser deposition technique, but also to effectively overcome the film thickness effect of the (RE,Y)-123 superconducting film containing mixed artificial pinning centers, hence the in-field current carrying capacity of the superconducting film is significantly improved in industrialized high-speed production.

An ultra-thin film superconducting tape and method for fabricating same is disclosed. Embodiments are directed to a superconducting tape being fabricated by processes which include removing a portion of the superconducting tape's substrate subsequent the substrate's initial formation, whereby a thickness of the superconducting tape is reduced to 15-80 μm.

A method of producing polycrystalline Y.sub.3Ba.sub.5Cu.sub.8O.sub.y (Y-358) whereby powders of yttrium (III) oxide, a barium (II) salt, and copper (II) oxide are pelletized, calcined at 850 to 950° C. for 8 to 16 hours, ball milled under controlled conditions, pelletized again and sintered in an oxygen atmosphere at 900 to 1000° C. for up to 72 hours. The polycrystalline Y.sub.3Ba.sub.5Cu.sub.8O.sub.y thus produced is in the form of elongated crystals having an average length of 2 to 10 μm and an average width of 1 to 2 μm, and embedded with spherical nanoparticles of yttrium deficient Y.sub.3Ba.sub.5Cu.sub.8O.sub.y having an average diameter of 5 to 20 nm. The spherical nanoparticles are present as agglomerates having flower-like morphology with an average particles size of 30 to 60 nm. The ball milled polycrystalline Y.sub.3Ba.sub.5Cu.sub.8O.sub.y prepared under controlled conditions shows significant enhancement of superconducting and flux pinning properties.