Crystal structure of Nd2BaCu3O7.3 determined from X-ray and neutron powderdiffraction data

In the present paper we report crystal structure of insulating compound Nd1 .9Ba1.1Cu3O7.28-the Nd-rich terminating point of Nd1+xBa2-xCu3Oz solid solu tions. This phase has an orthorhombic lattice with alpha = 3.8565(1) Angstr om, b = 7.7724(3) Angstrom, c 22.9862(8) Angstrom. The space group Ammm was determined on the basis of IR and Raman spectroscopic data and electron di ffraction analysis. The crystal structure was solved and refined from the p owder XRD and time-of-flight neutron diffraction data. Neodymium atoms on t he barium site compared to conventional NdBa2Cu3O7 crystal are ordered and form a face-centered supercell, while additional oxygen atoms occupy vacant chain sites in the vicinity of barium atoms.