Jc in high magnetic field of bi-layer and multi-layer structures for high temperature superconductive materials

To improve the chemical stability, as well as the critical current density (J.sub.C) of a superconductive material in an external magnetic field, copper-oxide coating materials have been developed. In some embodiments, these coating materials include a composition with the formula R.sub.1-x Ca.sub.x Ba.sub.2-y La.sub.y Cu.sub.3-z M.sub.z O.sub.7-.delta., where R is a rare-earth element (e.g., La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, or Y), M is a transition metal (e.g., Mn, Re, Fe, Os, Co, Rh, Ir, Ni, Pd, Pt, Ag, Au, Zn, Cd, or Hg), 0.ltoreq.x.ltoreq.0.4, 0.ltoreq.y.ltoreq.0.4, and 0.ltoreq.z.ltoreq.1.0. These coating materials are preferably used as a surface layer on superconductive materials to impart corrosion resistance and an improved critical current density when the layers are exposed to magnetic fields