The work reported in this paper aims at a better understanding of doping effects on high temperature superconducting YBa2Cu3O7−δ (YBCO or M-doped YBCO), in the form of large grains, fabricated by the top seeded melt-growth process. The study focused on the performance of YBCO large grains doped with Co, Ga, Ni and Zn substituting for the Cu site. The rate of Tc suppression with dopant concentration varies significantly among different dopants. Zn doping shows the highest depression rate, followed by Ni, Ga and Co doping. This we attribute to the fact that Zn and Ni substitute at Cu (2) sites on CuO2 planes in the lattice, whereas Co and Ga occupy Cu (1) sites along CuO chains and they have different magnetic moments. Trapped field, levitation force and Jc are enhanced due to pinning caused by local suppressed superconducting regions, and the enhancement effects are the highest in the case of Zn doping.

Ni and Ni-based alloys have received considerable attention as the substrates for HTS coated conductors. A critical step in the successful fabrication of coated conductor composites on metal substrates is to produce cube texture by mechanical deformation using the rolling assisted biaxial textured substrate (RABiTS) approach. In this paper, we investigated the effects of mechanical deformation and heat treatment on the growth of texture in nickel and nickel–tungsten alloys with the objective of understanding mechanisms of mechanical texturing in coated conductor substrates. The results show that the sharpest cube texture is obtained by cold rolling nickel and nickel tungsten alloys in passes of less than 5% deformation followed by annealing at high temperature.

SrTiO3 buffer layers have been deposited on rolled Ni substrates using metal organic deposition (MOD) for HTS-coated conductors. The MOD process is based on the formation of the SrTiO3 layer coated on the surface of a Ni substrate using dip-coating as well as spin-coating techniques from a solution-based precursor, which is prepared by dissolving strontium acetate and titanium (IV) butoxide in acetic acid and methanol. The films were annealed at 950 °C for 2 h under 5% H2–Ar gas flow. X-ray diffraction (XRD) shows that the buffer layers on the Ni tape are highly oriented. The pole figure indicates a single cube-on-cube texture in addition to SEM and AFM observations revealing a continuous, dense, smooth and crack-free microstructure for the coated buffer. These results offer the potential of further manufacturing coated conductors with high current density.

There are several motivations for increasing the diameter of melt textured single domain discs. The maximum magnetic field produced by a trapped field magnet is proportional to the radius of the sample. Furthermore, the availability of trapped field magnets with large diameter could enable their use in applications that have traditionally been considered to require wound electromagnets, such as beam bending magnets for particle accelerators and electric propulsion. We have investigated the possibility of using large area epitaxial growth instead of the conventional point nucleation growth mechanism. This process involves the use of large Y123 seeds for the purpose of increasing the maximum achievable Y123 single domain size. The hot seeding technique using large Y-123 seeds was employed to seed Y-123 samples. Trapped field measurements indicate that single domain samples were indeed grown by this technique. Microstructural evaluation indicates that growth can be characterized by a rapid nucleation followed by the usual peritectic grain growth which occurs when large seeds are used. Critical temperature measurements show that no local Tc suppression occurs in the vicinity of the seed. This work supports the suggestion of using an iterative method for increasing the size of Y-123 single domains that can be grown.

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