Abstract
Structural properties of homogeneous orthorhombic and tetragonal powder samples (6.1≤x≤7.0), prepared by a careful absorption-desorption procedure, were investigated by elastic neutron scattering. With decreasing oxygen content the distance between Cu(2)-O(2,3) planes and Cu(1)-O(4)-Cu(1) chains increases and the oxygen 2q(0,0,z) apex atoms O(1) move closer to the Cu-O-Cu chains. The copper-oxygen (1) distances do not vary continuously in the z direction but seem to change more rapidly when x<6.5. The change of these distances can be correlated to the suppression of superconductivity in orthorhombic . A distinction between the large anisotropic vibrational amplitudes of the Cu(1)-O(4)-Cu(1) broken-chain oxygen atoms and a split-site model for O(4) is not possible on the basis of the present data.
- Received 20 March 1989
DOI:https://doi.org/10.1103/PhysRevB.40.4472
©1989 American Physical Society