Nanostructural Evolution of Intermediate Grown Superconducting Joint Layers Between GdBa2Cu3Oy Coated Conductors

We have fabricated GdBa2Cu3Oy (GdBCO) jointed coated conductors (CCs) using a method in which intermediate grown superconductive (iGS) layers of (Y,Gd)Ba2Cu3Oy ((Y,Gd)BCO) are formed from an YBa2Cu3Oy precursor material to investigate their growth mechanism in the superconducting joint. We characterized the nanostructural evolution of the iGS layers by in-plane x-ray diffraction, transmission electron microscopy, and scanning transmission electron microscopy. The iGS layers contained Gd elements and were mainly composed of (Y,Gd)BCO grains. The c-axis oriented (Y,Gd)BCO grains nucleated on the GdBCO layers of both a joining strap and a CC. The thickness of the c-axis oriented (Y,Gd)BCO grains grew with time during the joining process at 800 °C, and finally both of the GdBCO layers were jointed together by the c-axis oriented (Y,Gd)BCO grains, resulting in a well-defined superconducting joint.