Structural architecture of superconducting oxides

Abstract

The crystal structures of Ba 2YCu 3O 7, La n+1Cu nO 3n+1, Bi 2Sr 2Ca n−1Cu n O 2n+4 and TlBa 2Ca n−1Cu nO 2n+3 ( n=1−3) can be considered as a combination of structural subunits with (Ca, Sr) CuO 2, CaTiO 3 and VH structure. The VH and (Ca, Sr) CuO 2 units are linked to CaTiO 3 units in symmetrical combinations. The oxygen content and formal valence of metal atoms vary with the number of CaTiO 3 structural units. Eight different formulas M xO y ( x⩽8) with twenty-three different crystal structures and formal valence of M atoms are suggested for possible candidates in addition to the fifteen experimental structures.