A superconducting bulk magnet comprising a plurality of superconducting bulk materials combined, in which breakage of superconducting bulk materials is prevented and a strong magnetic field can be generated, that is, a superconducting bulk magnet comprising a plurality of superconducting bulk materials, each comprising a single-crystal formed RE.sub.1Ba.sub.2Cu.sub.3O.sub.y (RE is one or more elements selected from Y or rare earth elements, where 6.8y7.1) in which RE.sub.2BaCuO.sub.5 is dispersed and each provided with a top surface, a bottom surface, and side surfaces, combined together, in which superconducting bulk magnet, bulk material units, each comprising a superconducting bulk material and a bulk material reinforcing member arranged so as to cover a side surface of the same, are arranged facing the same direction and contacting each other to form an assembly, a side surface of the assembly is covered by an assembly side surface reinforcing member, a top surface and bottom surface of the assembly are respectively covered by an assembly top reinforcing member and an assembly bottom reinforcing member, and the assembly side surface reinforcing member, the assembly top reinforcing member, and the assembly bottom reinforcing member are joined into an integral unit, is provided.

An oxygen sensor element that can achieve electric power saving without losing sensor characteristics has a structure in which an outer surface of a ceramic sintered body as a sensing layer made of a composition LnBa.sub.2Cu.sub.3O.sub.7?? (Ln denotes rare earth element) is covered with heat insulating layers. A heat insulating material having a composition Ln.sub.2BaCuO.sub.5 is used for the heat insulating layers, and that composition Ln.sub.2BaCuO.sub.5 is added with 20 mol % of LnBa.sub.2Cu.sub.3O.sub.7??. This allows a sintering behavior of the heat insulating layers to come close to a sintering behavior of the sensing layer, and can thus prevent the occurrence of separation of the layers and cracks. The oxygen sensor element has a sandwich structure where the sensing layer is sandwiched between the heat insulating layers, thereby reducing the amount of heat dissipated from the sensing layer, and making it possible to achieve electric power saving.

A superconducting wire according to an embodiment includes: a substrate; a first region provided on the substrate and containing a first rare earth element, Ba, Cu, and O; a second region provided on the substrate and containing a second rare earth element, Ba, Cu, and O; and a third region provided on the substrate, provided between the first region and the second region, and containing a third rare earth element, Pr, Ba, Cu, and O. A surface density of particles having an aspect ratio of 3 or more present on a surface of the third region is larger than a surface density of particles having an aspect ratio of 3 or more present on surfaces of the first region and the second region.

A superconducting composition of matter including overlapping first and second regions. The regions comprise unit cells of a solid, the first region comprises an electrical insulator or semiconductor, and the second region comprises a metallic electrical conductor. The second region extends through the solid and a subset of said second region comprise surface metal unit cells that are adjacent to at least one unit cell from the first region. The ratio of the number of said surface metal unit cells to the total number of unit cells in the second region being at least 20 percent.

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.

A solid oxide fuel cell comprises a solid electrolyte layer, a barrier layer, and a cathode. The cathode includes a cathode current collecting layer and a cathode active layer. The cathode active layer includes a plurality of micro-cracks in a surface region within a predetermined distance from the interface between the barrier layer and the cathode active layer.

A solid oxide fuel cell comprises a solid electrolyte layer, a barrier layer, and a cathode. The cathode includes a cathode current collecting layer and a cathode active layer. The cathode active layer includes a plurality of micro-cracks in an interface region within a predetermined distance from the interface between the cathode current collecting layer and the cathode active layer.

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 m and an average width of 1 to 2 m, 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.

A superconducting composition of matter including overlapping first and second regions. The regions comprise unit cells of a solid, the first region comprises an electrical insulator or semiconductor, and the second region comprises a metallic electrical conductor. The second region extends through the solid and a subset of said second region comprise surface metal unit cells that are adjacent to at least one unit cell from the first region. The ratio of the number of said surface metal unit cells to the total number of unit cells in the second region being at least 20 percent.

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.