Bismuth-lead-strontium-calcium-cuprate superconductors
AssigneeAmerican Telephone and Telegraph Company, AT&T Bell Laboratories
InventorsRobert J. Cava, Steven A. Sunshine
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Abstract
Novel superconductive Pb-substituted oxides are disclosed. The oxides all have layered perovskite-like crystal structure, and manifest superconductivity (R=o) above about 77K. The materials are described by the nominal formula X.sub.2+x M.sub.3-x Cu.sub.2 O.sub.8.+-..delta., where X is Bi and Pb, M is Sr and Ca, 0.ltoreq..times..ltoreq.0.3, 0.ltoreq..delta..ltoreq.0.5, the Pb/Bi ratio is between about 0.2 and about 0.5, and the Sr/Ca ratio is between 0.5 and 2.
Claims2
A superconductive element comprising an effective amount of material nominally of perovskite structure and of nominal composition X.sub.2+x M.sub.3-x Cu.sub.2 O.sub.8.+-..delta., where X is Bi and Pb, M is Sr and Ca, x is equal to or greater than 0 and less than about 0.3, .delta. is greater than about 0 and less than about 0.5, the Pb/Bi ratio is between about 0.2 and about 0.5, the Sr/Ca ratio is between about 0.5 and about 2, and the element manifesting a transition temperature T.sub.c (R=o) of at least 77 K.
Dependencies are inferred from the claim text.