Microstructural characterization of GdBa2Cu3Oy superconductive layer fabricated by in-plume pulsed laser deposition

Abstract

A GdBa2Cu3Oy (GdBCO) layer was fabricated on Hastelloy with a textured CeO2/LaMnO3/MgO/Gd–Zr–O buffer layer by in-plume pulsed laser deposition using a reel-to-reel tape transfer system. The microstructures of the coated conductor were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and a focused ion beam (FIB)–SEM dual beam system. Numerous outer-growth grains form on the GdBCO surface. Their shapes of these grains can be broadly categorized into three types: rectangular, pyramidal and circular. Cross-sectional TEM images of the GdBCO layer indicate that it is predominantly composed of grains with their c-axis aligned normal to the substrate. The circular grains were identified as being oriented along the c-axis, but rotated 45° in-plane relative to the matrix grains, while the rectangular grains were identified as those with their a-axis parallel to the substrate normal, and the pyramidal grains with their c-axis tilted away from the substrate normal. In addition, TEM revealed that CuO grains formed under the tilted grains and the rotated grains. A 3D reconstructed image of the GdBCO layer using an FIB–SEM dual-beam system clearly shows the distribution of those outer-growth grains and the CuO.