A NEUTRON DIFFRACTION STUDY OF A SUPERCONDUCTING CUPRATE OF THE Bi–Ca–Sr–Cu–O SYSTEM CONTAINING TWO Cu-O SHEETS

The structure of a nominally Ca-rich composition of the n = 2 member of the Bi 2 (Ca, Sr) n+1 Cu n O 2n+4 series has been investigated by neutron diffraction profile analysis. The results suggest that the Amaa space group may be more appropriate than the Fmmm space group.