The Influence and Control of Oxygen Stoichiometry in High T sub c Superconductors

There are now several different layered cuprate structures or systems which exhibit high temperature superconductivity. Each seems to have a unique relationship between its properties and oxygen content. A number of the systems, e.g., Ba sub 2 LnCu sub 3 O sub 7-x and Pb sub 2 Sr sub 2 Y sub 1-x Ca sub x Cu sub 3 O sub 8+y, preserve this general structure over exceptionally wide ranges of oxygen stoichiometry.