Neutron powder-diffraction studies of superconducting oxygenated and fluorinated Hg-1201 phases

E. V. Antipov, A. M. Abakumov, V. L. Aksenov, A. M. Balagurov, S. N. Putilin, M. G. Rozova

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Abstract

Neutron powder-diffraction (NPD) experiments were carried out for monophasic oxygenated HgBa2CuO4+δ (Tc = 71,98 and 83 K) and fluorinated HgBa2CuO4Fδ (Tc = 97 and ∼ 80 K) samples with different oxygen or fluorine contents. The NPD refinements revealed a stoichiometric cation composition and extra anions were found to be located only in the middle of the Hg mesh. In both series the dependencies of Tc versus δ exhibit parabolic-shaped behavior, but these curves are shifted away from each other along the δ axis. NPD showed twice the amount of extra fluorine (δ ≈ 0.24 and 0.32) in comparison with those for the oxygenated Hg-1201 phases with comparable Tc's (δ = 0.12 and 0.19). This supports an ionic model of hole doping in Hg-1201: two holes per extra oxygen and one hole per extra fluorine. The structural data showed that the apical distances in Hg-1201 depend strongly on the number of dopant atoms rather than on their charge. The exchange of extra oxygen for a double amount of fluorine causes an enhanced shortening of the apical Cu-O bond distances, while the in-plane distances, as well as Tc, do not vary,

Original languageEnglish
Pages (from-to)773-779
Number of pages7
JournalPhysica B: Condensed Matter
Volume241-243
DOIs
Publication statusPublished - Jan 1 1997

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Keywords

  • Fluorination
  • Hg-1201
  • Neutron powder diffraction

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Electrical and Electronic Engineering

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