Structure of La 5Cu 5O 13.35 by High-Resolution Synchrotron X-Ray Diffraction

Abstract

The structure of La 5Cu 5O 13.35 was refined from high-resolution synchrotron X-ray diffraction data using the Rietveld method. The unit cell is monoclinic, space group P 2/ m- C 12 h (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) Å 3, Z = 1, D x = 7.085 g/cm 3 at T = 300 K. 265 independent reflections were included in the refinement and a reasonably good fit was obtained with final R values R I = 9.28%, R p = 14.51%, R wp = 19.60%, and goodness-of-fit S wp = 1.573. The structure is of the oxygen-defect Perovskite type and is composed of one distorted CuO 6 octahedron and four distorted CuO 5 square pyramids per crystallographic unit cell. The polyhedra of La 5Cu 5O 13+δ display a three-dimensional connectivity with a unique oxygen ordering which creates one-dimensional channels of vacancies along the b-axis.