摘要 |
<p>A corrosion resistant high temperature superconductor and a method of preparing said superconductors involving substitution of ions in the lattice to relieve stress and strain caused by mismatches bond lengths. Specific examples of such superconductors are Y1-yCayBa2-yLayCu3O7-d where O < y < 1.0 and O < d < 1 and YBa2-ySryCu3O7-d where O < y < 2 and O < d < 1. In YBa2Cu3O7-d structure, the internal stresses estimated from the difference between the bond valence sum and the formal oxidation state for Ba and Cu ions indicate that the Ba atom is too large for Cu-O cage at oxygen stoichiometric d = 0 and too small at d = 1. Therefore, the Ba (1.52 Å) is substituted by La (1.27 Å) and for keeping the same oxidation state of Cu as in the prototype material the Ca (1.12 Å) equivalent to La replaces the Y (1.019 Å). Various geometries for the stable superconductor formulations are described including monolithic bulk ceramic, encapsulated ceramic, monolithic film, encapsulated film and superlattice forms.</p> |