Characterization of the Europium Substituted Superconducting Bi sub 2 Sr sub 2 CaCu sub 2 O sub 8+y Phase

Effects of Eu substitution on the stoichiometry, structure and superconductivity of the Bi sub 2 Sr sub 2 CaCu sub 2 O sub 8+y phase have been investigated. Partial replacement of Ca by Eu promotes the single-phase formation and leads to an uptake of extra O into the structure. Oxygen content in the Bi sub 2 Sr sub 2 Ca sub 1--x Eu sub x Cu sub 2 O sub 8+y materials was determined by the thermogravimetric hydrogen reduction method. In an attempt to locate the intercalated O atoms, X-ray, neutron and electron diffraction techniques were used. In addition, the samples were characterized by ac magnetic susceptibility measurements and by exp 151 Eu Mossbauer spectroscopy. The applicability of these methods and the results obtained thereby are discussed.