We have studied the sintering parameters of YBa2Cu3O7-x (YBCO) coatings produced by electrophoretic deposition (EPD) on Ag and Ni substrates. The maximal sintering temperature is ∼ 930°C due to partial melting and chemical contamination for Ag and Ni substrates respectively. Increasing the sintering duration does not improve significantly the densification. When Ar sintering atmosphere is used, the coating density is strongly increased on Ag substrates while adhesion is poor on Ni substrates. The Ar-sintered YBCO coating deposited on planar Ag substrate displays a significant magnetic shielding effect for low frequency applied magnetic induction.

Metal organic deposition (MOD) is one of the attractive processes for coated conductor applications because it is a non-vacuum cost-effective process. Many research groups have successfully fabricated high-JC YBCO coated conductor on the RABiTS and IBAD-YSZ or GZO template with the MOD process. Reports on MOD-processed YBCO coated conductors prepared on the IBAD-MgO template, however, are hardly found. The precursor solution was coated on the CeO2 capped IBAD-MgO template using the slot-die coating method, calcined at a temperature of 550oC, and fired at high temperatures for 2 h 30 min in a reduced oxygen atmosphere. Optimal processing resulted in YBCO coated conductors exhibiting JC value of 0.75 MA/cm2 at 77 K in self-field. The JC values of YBCO coated conductors were found very sensitive to their microstructure, critical temperature, and in-plane texture.

Coated conductor samples, prepared by reactive co-evaporation, are investigated with respect to the hole-doping dependence of the critical current density. The samples are annealed in an atmosphere of variable oxygen content after which critical currents, critical temperature and the c-axis lattice spacing are measured. The lattice spacing increases with decreasing oxygen content, consistent with literature data. These co-evaporated samples show hole overdoped behavior with respect to the maximum Tc. The achievable range of hole doping in these samples seems to depend on surface coverage. Both self-field and in-field Jc at 75.5 K have a maximum in the overdoped region but at less than maximum oxygen content. The reason for the overdoping of these samples is discussed briefly in terms of Y-Ba disorder.

Certain practical applications of YBCO coated conductors (CC) involve superconducting tapes wound in coils. In such a configuration the superconducting tape is arranged as closely packed turns, leading to an increase of the magnetic field generated by the current in the tapes and, consequently, a significant increase in the AC losses, with respect to an ‘isolated’ tape. In order to predict and reduce the refrigeration requirements of applications, it is therefore very important to be able to quantify the magnitude of such AC losses, both experimentally and by means of numerical calculations.

We examine the influence of various substrate preparation procedures for ion-beam assist deposition (IBAD) texturing of MgO. IBAD-MgO nano-texturing is very sensitive to the nucleation surface, and surface roughness has an important influence on the texture of the MgO layer. We studied Hastelloy C-276 metal alloy as the substrate. The untreated substrate is leveled by either electropolishing, mechanical polishing or solution deposition. All three methods are applied to continuously moving tapes in long lengths. The RMS surface roughness decreases from 20-50 nm for the untreated substrate to 0.5 nm, 0.3 nm and 1 nm respectively. The in-plane and out-of plane crystalline alignment of the MgO layer improves as the roughness is decreased below 2 nm.

We present a new reel-to-reel method for growth of high temperature super-conducting (HTS) films by reactive co-evaporation on flexible metal tapes. We have demonstrated proof of principle for this method with a small laboratory-scale setup using 8 cm long tape pieces. YBa2Cu3O7-δ is deposited on ion-beam assisted deposition textured MgO layers on top of flexible polycrystalline metal tapes. Critical current densities at 75.5 K of over 2 MA/cm2 have been achieved in HTS films with over 2 μm in thickness, yielding a self field critical current of 450 A/cm-width. A 4.5 μm thick film had a self field critical current of 590 A/cm. We discuss some practical possibilities for manufacturing of superconducting wire using this process and present new areas of research that are still needed.

We present a time-resolved magneto-optical imaging study of YBa2Cu3O7-δ coated conductors in alternating current regime. The evolution of the magnetic flux density distribution in the superconducting samples is imaged at small steps of the phase of the applied AC current. The flux penetration during the phase evolution is inhomogeneous due to the grain structure of the coated conductor. A quantitative analysis of the images show how grain boundary network affects the overall behavior of the flux and current density evolution.

YBa2Cu3O7-x (Y123) superconducting thin films can maintain high critical current densities in applied magnetic fields up to a few Tesla at 77 K. Even so, this does not preclude the intentional addition of alternate flux pinning centers in the Y123 films to further optimize their in-field Jc. Unfortunately, many methods to incorporate flux pinning centers into Y123 thin films introduce additional steps and/or re-optimization of the deposition parameters for a given addition. Identifying potential additions that can optimize the performance of YBCO films without changing the deposition conditions would be ideal. The work presented here is an extension of earlier work and demonstrates new dopants and possibilities for introducing pinning centers by the route of minute doping or nanodoping. Preliminary results of a study to determine if minute doping can be performed with smaller lanthanide atoms (Tm, Lu), non-lanthanide atoms (Sc) and Ba-site substitution (Sr) are presented. All samples were deposited under identical conditions as pure YBCO. The new dopants will be discussed in addition to those previously presented (Tb, Pr, Ce, Nd, and La). Critical current density data will be presented for 65 K and 77 K in fields up to 9T in addition to new structural data obtained by cross-sectional TEM.