A process for the fabrication of high-quality and near-net-shaped superconducting specimens of (Y-123) with uniformly distributed fine (Y-211) is discussed. The process involves the fabrication of 211 preforms by conventional ceramic routes such as uniaxial and isostatic pressing, injection moulding and slip casting, and pressureless infiltration basically from a reservoir containing liquid phases. A compact of 123 or 123 rich in liquid phases(s), acting as a source of liquid phases, is placed in contact with the 211 preform, and heated above the peritectic temperature of 123. The liquid from the source compact infiltrates the 211 filler and the peritectic reaction occurring between the preform material (211) and the matrix (liquid phases) during slow cooling from the peritectic temperature results in the growth of 123 with uniformly distributed fine 211 particles. We have also demonstrated that the present process can be extended to the fabrication of other rare earth (RE) superconductors where a solid solution of the kind occurs due to comparable size of the RE and Ba atoms, by choosing the RE = Gd system as an example. Herein the advantages and bounds of the process are reviewed; the effect of various cooling rates on the growth kinetics of 123 and the resulting macro- and microstructures are discussed. Fabrication of composites containing fine and very uniformly distributed Ag is also demonstrated by the process. Comparisons are made between the characteristics of the samples produced in the present process and the existing melt texturing process. The utility of the process is demonstrated by the fabrication of a three-dimensional component - a hollow cylinder.

The development of foams from a variety of substances such as polymers, glasses, metals and ceramics has led to many important applications of foam structures. A large open porosity, along with a high surface area and good mechanical properties, brings about novel properties and makes foams attractive for various applications. In addition to conventional applications such as filters, shock absorbers, heat exchangers, catalysts or lightweight constructions, porous structures are increasingly being considered for advanced functional materials, such as piezoelectrics revealing novel and improved properties. Until now, superconducting materials have not been processed in foam structures. However, a superconducting foam reveals properties which are highly interesting both for applications such as efficient heat extraction from superconducting components, e.g. in fault current limiters, and for fundamental investigations of e.g. surface pinning. We detail a manufacturing process for superconducting, pseudo-single crystalline foams of YBa2Cu3O7−x (Y123) based on a combination of standard ceramic foam processing and an infiltration method.

Non-destructive magneto-strain analysis of YB2Cu3Oy superconducting magnets using neutron diffraction in the time-of-flight mode J. Appl. Phys. 112, 063923 (2012) Thermoelectric properties of YBa2Cu3O7−δ-La2/3Ca1/3MnO3 superlattices Appl. Phys. Lett. 101, 131603 (2012) Analog of the susceptibility spectrum for levitation forces between a superconductor and a permanent magnet J. Appl. Phys. 112, 033908 (2012) Effect of thermal inhomogeneity for terahertz radiation from intrinsic Josephson junction stacks of Bi2Sr2CaCu2O8+δ Appl. Phys. Lett. 100, 242603 (2012) Recycling failed bulk YBCO superconductors using the NdBCO/YBCO/MgO film-seeded top-seeded melt growth method Second-phase, nanoscale inclusions of composition Y 2 Ba 4 CuM O y (M ϭU, Nb, Ta, W, Mo, and Re͒, which form artificial pinning centers, have been introduced into large, single-grain ͓rare-earth ͑RE͔͒-Ba-Cu-O superconductors. A significant improvement in critical current density is observed in these samples, due presumably to various combinations of normal conducting, paramagnetic, and geometrical properties of the Y 2 Ba 4 CuM O y particles in the superconducting (RE͒Ba 2 Cu 3 O 7Ϫ␦ ͑RE-123͒ phase matrix. These Y 2 Ba 4 CuM O y phase particles are chemically stable in the Ba-Cu-O liquid during peritectic solidification, unlike Y 2 BaCuO 5 ͑Y-211͒ phase particles in Y-Ba-Cu-O, which opens a processing window for the fabrication of nanostructured large, single-grain ͑RE͒-Ba-Cu-O superconductors with enhanced flux pinning for high-field engineering applications.

No abstract