A liquid phase processing method for the fabrication of bulk YBa2Cu3Ox superconductors with large current carrying capacity has been developed. Slow cooling through the peritectic transformation (1030–980 °C) has been shown to control the microstructure of these superconductors. A cooling rate of 1 °C/h in this temperature range has yielded a microstructure with long plate type, thick grains oriented over a wide area. Current density up to 18 500 A/cm2 has been obtained by continuous direct current measurements and in excess of 62 000 A/cm2 with pulse current of 10 ms duration and 75 000 A/cm2 using 1 ms pulse. The strong magnetic field dependence observed in sintered bulk 1-2-3 superconductors is also minimized to a large extent where a current density in excess of 37 000 A/cm2 is obtained in a field of 6000 G.

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Thin film growth by a non-vacuum deposition technique, namely, the chemical solution deposition (CSD) method, is reviewed with emphasis on the growth of various oxide films and their properties. Various aspects of the solution chemistries for the different routes are discussed, and the effects of solution precursor properties on the conversion of the as-deposited film to the desired phase are also discussed. Crystal structures and functional properties common to many oxide materials are briefly reviewed.

Melt processing is the most prominent method utilized in the fabrication of bulk YBa2Cu30x(123) because of the superior transport and magnetic properties of this material. Due to the Y-diffusion-controlled growth mechanism of 123, the maximum allowable growth rate is sensitive to the size and distribution of the Y2BaCuOS precipitates. In addition, a slow cooling rate and a slow growth rate have to be employed to maintain the stability of the 123 planar growth front. Among the many melt-texturing methods and modifications, seeded directional solidification has the potential to produce long single-domained samples of large cross-sectional area with the strongly superconducting a-b planes aligned along the sample axis. Steady progress has also been achieved in flux-pinning enhancement through defect engineering. This includes the introduction and modification of defects such as twins, irradiation damage and second-phase inclusions. In particular, high-temperature mechanical deformation has been shown to be effective in increasing the dislocation density and results in improved Jc as well as reduced J, anisotropy.

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Iron-clad MgB2 superconducting tapes with a MgB2 core cross-section area of 1.07×10−3 cm2 were fabricated using the standard powder-in-tube method. The starting precursor was ultrafine Mg and B mixture powder prepared by high-energy ball milling. Very good grain connections as well as grain refinement were obtained in tapes annealed at 850 °C. Under a 1.5-T external magnetic field, Jc is 1.07×105 and 6.54×103 A/cm2 at 20 and 30 K, respectively. An extrapolation to zero field at 20 K gives a Jc of 3.0×105 A/cm2.

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