Structural and transport properties of biaxially aligned YBa2Cu3O7−x films on polycrystalline Ni-based alloy with ion-beam-modified buffer layers

Abstract
Biaxially aligned YBa2Cu3O7−x (YBCO) thin films were produced on polycrystalline Ni‐based alloy, by using biaxial yttria‐stabilized‐zirconia (YSZ) intermediate layers formed by off‐normal ion‐beam‐assisted deposition. Most explicit in‐plane alignment was obtained when the YSZ layer formed with the beam‐incident angle of 55° from substrate normal. JcB characteristics and angular dependence of Jc on the magnetic field were measured. 5.0×105 and 5.5×104 A/cm2 were obtained at 77 K with 0 and 8 T, respectively. The distribution of misorientation angles of in‐plane a and b axes between YBCO grains was evaluated by both x‐ray pole figure measurement and planar observations of transmission electron microscopy. 50% of the grains had the misorientation angles restricted within ±5°. From the image of dislocations, the elastic strains at grain boundaries were estimated to be relaxed with lower misorientation angle. The high‐Jc properties are understood to be obtained by the current paths through low‐angle grain boundaries.