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).

Recent efforts in the development of YBa2Cu3O7-x (YBCO) coated conductors are devoted to the increase of the critical current Ic in magnetic fields. This is typically realized by growing thicker YBCO layers as well as by the incorporation of artificial pinning centers. We studied the growth of doped YBCO layers with a thickness of up to 7 µm using pulsed laser deposition with a growth rate of about 1.2 nm/s. Industrially fabricated ion-beam textured YSZ templates based on metal tapes were used as substrates for this study. The incorporation of BaHfO3 (BHO) or Ba2Y(Nb0.5Ta0.5)O6 (BYNTO) secondary phase additions leads to a denser microstructure compared to undoped films. A purely c-axis-oriented YBCO growth is preserved up to a thickness of about 4 µm, whereas misoriented texture components were observed in thicker films. The critical temperature is slightly reduced compared to undoped films and independent of film thickness. The critical current density Jc of the BHO-and BYNTO-doped YBCO layers is lower at 77 K and self-field compared to pure YBCO layers; however, Ic increases up to a thickness of 5 µm. A comparison between films with a thickness of 1.3 µm revealed that the anisotropy of the critical current density Jc() strongly depends on the incorporated pinning centers. Whereas BHO nanorods lead to a strong B||c-axis peak, the overall anisotropy is significantly reduced by the incorporation of BYNTO forming a mixture of short c-axis-oriented nanorods and small (a-b)oriented platelets. As a result, the Jc values of the doped films outperform the undoped samples at higher fields and lower temperatures for most magnetic field directions.

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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 .