Superconductive aluminum/YBa2Cu3O<i>x</i> composites stabilized by oxygen/fluorine donors

Abstract

A fabrication technique for producing bulk and irregular-shaped aluminum/high Tc superconductor composites by traditional powder metallurgy method is reported. During the course of fabrication, the oxygen stoichiometry can be maintained at the desired level in order to retain superconductivity by addition of certain metal oxides or metal carbonates with low oxidation tendency, e.g., Ag2O, Ag2CO3, and CdO. Moreover, replacement of oxygen with fluorine is also possible by addition of certain unstable fluorides like AgF. Superconductivity measurements of Al/YBa2Cu3Ox random composites with additions of different oxygen or fluorine donors show a similiar or improved Tc in comparison to the pure 123 compound. The concept of oxygen/fluorine donor can also be used in other fabrication techniques of metal/123 composites to stabilize the oxygen/fluorine stoichiometry.