Neutron Diffraction Study of the Ferromagnetic Copper Oxide La_1.8Ba_1.2CuO₅

抄録

The crystal structure of the ferromagnetic copper oxide La_2−xBa_1+xCuO₅ (x=0.2) has been refined by Rietveld analysis of TOF neutron powder diffraction data taken at room temperature. It is tetragonal with space group P4/mbm, and its lattice parameters are a=0.68652(1) nm and c=0.58698(1) nm. La³⁺ and Ba²⁺ ions form LaO₈ and BaO₁₀ polyhedra, respectively. The La site is 11% occupied by excess Ba atoms, and 2.5% of the Ba site are substituted by La atoms. No deficiencies could be detected in a Cu site or two O sites.