The Crystal Structure of Superconducting La2CuO4.032 by Neutron Diffraction

Abstract

The structure of superconducting La₂CuO_4.032 has been determined by single-crystal neutron diffraction data. The excess oxygen, O4, is located between two adjacent LaO1 layers. The presence of O4 distorts the apical-oxygen O1 sublattice in such that each O4 forms a short bond (1.64 Å) with one O1, which indicates the formation of a strong covalent bond between these two atoms. The Cu and O2 sublattices as well as that of La are not affected by O4, however, 1.6% of the La cations increase their coordination from 9 to 10.