Structure of La₅Cu₅O_13.35 by high-resolution synchrotron X-ray diffraction

The structure of La5Cu5O13.35 was refined from high-resolution synchrotron X-ray diffraction data using the Rietveld method. The unit cell is monoclinic, space group P 2/m-C12h (No. 10), with a = 8.62884(5) Å, b = 3.83076(2) Å, c = 8.65148(5) Å, β = 90.2166(4)°, V = 285.973(4) Å3, Z = 1, Dx = 7.085 g/cm3 at T = 300 K. 265 independent reflections were included in the refinement and a reasonably good fit was obtained with final R values RI = 9.28%, Rp = 14.51%, Rwp = 19.60%, and goodness-of-fit Swp = 1.573. The structure is of the oxygen-defect Perovskite type and is composed of one distorted CuO6 octahedron and four distorted CuO5 square pyramids per crystallographic unit cell. The polyhedra of La5Cu5O13+δ display a three-dimensional connectivity with a unique oxygen ordering which creates one-dimensional channels of vacancies along the b-axis. © 1995 Academic Press. All rights reserved.