Superconductivity in the Bi-Sr-Ca-Cu-O Compounds with Noble Metal Additions.

The Bi-Sr-Ca-Cu-O superconductors have been doped with various noble metals and their superconducting properties have been investigated. The resistivity and magnetic susceptibility measurements on sintered Bi sub 4 Sr sub 2 Ca sub 2 Cu sub 4 O sub (16+x) containing 20% by weight of Au, Ag, or Pt-group metals indicate that Au and the Pt-group metals significantly suppress or eliminate the superconducting transition in Br- Sr-Ca-Cu-O. Only Ag is found to be benign, maintaining both the 115K and 85K transitions in the compound. This nonpoisoning behavior of silver is of significant technical importance because of the need for a proper stabilizing normal metal for composite superconductor wire, nonreactive crucible materials for melt processing or crystal growth, and suitable nonpoisonous substrates or barriers for thin or thick film superconducting devices.