Nanostructural characterization of Y123 and Gd123 with BaZrO3 rods fabricated by pulsed-laser deposition

Abstract

Both YBa2Cu3O7−x (Y123) and GdBa2Cu3O7−x (Gd123) layers with BaZrO3 (BZO) rods were deposited on Hastelloy tapes with textured buffer layers (CeO2/Gd2Zr2O7) using pulsed-laser deposition (PLD). Two volume percent of YSZ–Y123 and 2vol%YSZ–Gd123 were used as target materials. The critical current density (Jc) values of these layers in a magnetic field parallel to the substrate normal were enhanced compared with those of Y123 layers without BZO rods. In the entire incident angle of magnetic fields, the Jc reduction of the Gd123 layer with BZO rods were improved compared to that of the Y123 layer with BZO rods. Transmission electron microscopy was used to characterize the nanostructures of the specimens prepared by both focused ion beam and standard ion milling. The Y123 layer with BZO rods and the Gd123 layer with BZO rods were composed of c-axis oriented grains, in which BZO rods aligned in the [001] of Y(Gd)123 ware distributed homogeneously. The diameter of the BZO rods was about 5nm and the rods grew from the CeO2 interface to the surface. The orientation relationships between Y(Gd)123 and BZO were as follows: (001)Y(Gd)123//(001)BZO and (100)Y(Gd)123//(100)BZO. In the Gd123 with BZO rods, a high density of stacking faults in the (001) plane and distorted (001) planes were found. The formation of the BZO rods in the Y(Gd)123 and a high density of defects with respect to the (001) plane in the Gd123 were considered to enhance the Jc values in high magnetic fields.