Detailed structure of a Pb-doped Bi2Sr2CuO6 superconductor

Abstract

The crystal structure of (Bi1.82Pb0.18) (Sr1.84Pb0.16) CuO6 was determined from single-crystal intensity data measured on a four-circle diffractometer. The structure is orthorhombic, space group Cccm (No. 66); the lattice parameters: a=5.392(3) Å, b=24.603(5) Å, c=5.300(3) Å, V=703.2 (5) Å3 (the space group can be denoted as Amaa by a cyclic transformation of the cell constants). The R value was 0.048 for 418 unique reflections with I>3.00 σ(I). One of the O atoms bonded to Bi ions is disordered at two sites with a half occupancy and Beq=3.6(6) Å2; although the thermal parameter is not so large as that reported by Torardi et al. [Phys. Rev. B 38, 225 (1988)], the disorder suggests that the crystal has a lower symmetry. The valence state of the Cu ion in the present compound was evaluated to be trivalent based on the Cu-O distances [Asbrink and Norrby, Acta Crystallogr. B 26, 8 (1970)] and the valence of Bi was estimated in comparison with that in other compounds. The O(3) sublattice dynamics in these types of superconductors is discussed based on the structural investigations.

Source-reported materials — not catalogue approval

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