Characteristics of High-Jc GdBCO Coated Conductors Fabricated by the RCE-DR Process

We report the characteristics of GdBa2Cu3O7-delta (GdBCO) coated conductors (CCs) on LaMnO3 (LMO)-buffered IBAD MgO template, produced by the Reactive Co-Evaporation Deposition & Reaction (RCE-DR) process. The transport and magnetic critical current density (J(c)) values of GdBCO CC samples were 3.7 and 2.92 MA/cm(2) at 77 K in self-field for B//c, respectively. Analyses by transmission electron microscopy revealed that a large amount of elongated round Gd2O3 particles with 70-150 nm size and a small amount of the Cu-O phase were trapped in the GdBCO matrix, and a thick layer of the Cu-O phase was also found on the top surface of the GdBCO film, suggesting that the GdBCO film must be grown by the peritectic recombination reaction between Gd2O3 and a liquid phase. While both the GdBCO film and some Gd2O3 particles grown on the LMO-buffer layer were biaxially textured, the Gd2O3 particles fully trapped in the GdBCO matrix were randomly oriented. The GdBCO film by RCE-DR possessed slightly degraded value of exponent alpha similar to 0.84 in the power-law relationship J(c) similar to H-alpha and rather large anisotropy in field-orientation dependence of J(c), J(c)(theta), and thus refinement of Gd2O3 particles may be required for stronger flux pinning.