Jp. Hedges et al., SYNTHESIS, STRUCTURE, AND PROPERTIES OF THE HIGH-TEMPERATURE SUPERCONDUCTOR HGBA2CUO4+DELTA, Physical review. B, Condensed matter, 55(18), 1997, pp. 12776-12783
We report here the attempted synthesis of (Hg1-xCuy)Ba2CuO4+delta (0 l
ess than or equal to x less than or equal to 0.2, 0 less than or equal
to y less than or equal to 0.2, y less than or equal to x) and the re
sults of a detailed characterization of the structural and superconduc
ting properties of the resulting samples. Rietveld refinement of powde
r x-ray-diffraction data collected on all 15 samples synthesized found
no partial Cu occupancy of the Hg site. We therefore conclude that fo
r these samples no solid solution exists and the superconducting phase
is simply HgBa2CuO4+delta. Only one interstitial oxygen position O(3)
was found, located exactly at the center of the Hg plane. An analysis
of the structural refinements has produced a number of correlations b
etween the exact location of the Ba2+ cation within the unit cell and
a number of important superconducting parameters; these include the oc
cupancy of the O(3) site, the extent of oxidation of the CuO2 planes,
and the magnetic penetration depth.