The current transport capability of YBa 2 Cu 3 O 7 −x (YBCO) based coated conductors (CCs) is mainly limited by two features: the grain boundaries of the used textured template, which are transferred into the superconducting film through the buffer layers, and the ability to pin magnetic flux lines by incorporation of defined defects in the crystal lattice. By adjusting the deposition conditions, it is possible to tailor the pinning landscape in doped YBCO in order to meet specific working conditions (T, B) for CC applications. To study these effects, we deposited YBCO layers with a thickness of about 1-2 μm using pulsed laser deposition on buffered rolling-assisted biaxially textured Ni-W substrates as well as on metal tapes having either an ion-beam-textured YSZ buffer or an MgO layer textured by inclined substrate deposition. BaHfO 3 and the mixed double-perovskite Ba 2 Y(Nb/Ta)O 6 were incorporated as artificial pinning centers in these YBCO layers. X-ray diffraction confirmed the epitaxial growth of the superconductor on these templates as well as the biaxially oriented incorporation of the secondary phase additions in the YBCO matrix. A critical current density J c of more than 2 MA/cm² was achieved at 77 K in self-field for 1-2 μm thick films. Detailed TEM (transmission electron microscopy) studies revealed that the structure of the secondary phase can be tuned, forming c-axis aligned nanocolumns, ab-oriented platelets, or a combination of both. Transport measurements show that the J c anisotropy in magnetic fields is reduced by doping and the peak in the J c (θ) curves can be correlated to the microstructural features.Index Terms-Alternating beam assisted deposition (ABAD), coated conductors, inclined substrate deposition (ISD), pinning, pulsed laser deposition, RABiTS, YBa 2 Cu 3 O 7 −x (YBCO).

GdBa 2 Cu 3 O 7−x (GdBCO) films doped with up to 13.6 mol.% BaHfO 3 (BHO) have been grown by electron beam physical vapor deposition (EB-PVD). A critical current density J c at 30 K, 3 T of 2.34 MA/cm 2 has been achieved for a doping level of 10.6 mol.%. This is the first report of artificial pinning centers being successfully incorporated into REBa 2 Cu 3 O 7−x (REBCO, RE = Y, Gd, Dy . . .) via EB-PVD. The samples were grown on Hastelloy tapes coated with a MgO buffer layer deposited by inclined substrate deposition. The J c of the samples was characterized at 77 K, 1 T and at 30 K, 3 T. An increase in J c (30 K, 3 T) upon Hf addition has been observed in the whole angular range α. The level of Hf addition was found to heavily influence the kind of nanoprecipitate formed, with low levels of Hf causing a reduction in the anisotropy of J c (77 K, 1 T) and higher levels of Hf resulting in the formation of nanoprecipitates elongated parallel to the GdBCO ab-plane, causing an increase in the anisotropy of J c (77 K, 1 T). The largest J c (77 K, sf) measured was 0.63 MA/cm −2 .

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We grow BaHfO 3 (BHO) nanorods in REBa 2 Cu 3 O 7−x (REBCO, RE: Gd or Y) thin films on metal tapes coated with the inclined substrate deposited (ISD)-MgO template by both electron beam physical vapour deposition and pulsed laser deposition. In both cases the nanorods are inclined by an angle of 21°-29°with respect to the sample surface normal as a consequence of the tilted growth of the REBCO film resulting from the ISD-MgO layer. We present angular critical current density (J c ) anisotropy as well as fieldand temperature-dependant J c data of the BHO nanorod-containing GdBCO films demonstrating an increase in J c over a wide range of temperatures between 30 and 77 K and magnetic fields up to 8 T. In addition, we show that the angle of the peak in the J c anisotropy curve resulting from the nanorods is dependent both on temperature and magnetic field. The largest J c enhancement from the addition of the nanorods was found to occur at 30 K, 3 T, resulting in a J c of 3.0 MA cm −2 .

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