New series of compounds Bi 2ALaCuO 6.5 (A = Ca, Sr or Ba) isostructural to the superconducting phase Bi 2Sr 2CuO 6

Abstract

The basic structure of the new superconducting phases in the Bi or Tl/Ca, Sr and or Ba/Cu/O systems appears to be based on alternating Bi 2O 2 or Tl 2O 2 double layers and perovskite (Ca, Sr, Ba)OCuO 2 sheets. The discovery of the new series of compounds with the general formula Bi 2ALaCuO 6.5 with A = Ca, Sr or Ba isostructural to the n = 1 member sets the problem to the exact localization of the oxygen atoms in the sub-lattice. The excess of oxygen in such compounds cannot be explained by a structural type based on the intergrowth of rocksalt layers and stoichiometric perovskite sheets in the case of the n=1 member.