Neutron-diffraction study ofNdBa2Cu3O

Abstract

Two samples of NdBa2Cu307+"with zero-resistance transition temperatures of 85 K (x 0.06) and 90 K (x 0.18), respectively, were studied by using neutron-diffraction powder profile analysis. The compounds crystallize in the same orthorhombic, oxygen-deficient perovskite structure with space group Pmmm, in which both le (0, -, ', 0) and lb (-, ', 0,0) sites are occupied partially by oxygen atoms, with a majority of atoms being located in the le sites. The final refinements converge to weighted profile R factors, R~, of 7.05% and 7.58% for the 90and 85-K samples, respectively. The significant diff'erences between the two samples are the oxygen content and the regular changes of all the Cu -0 bond distances in the structures.

Crystal Structure of Nd2BaCu3O7.3 Determined from X-ray and Neutron Powder Diffraction Data

“…The crystal structures of Nd 1+ x Ba 2 - x Cu 3 O z solid solutions with x up to 0.5 were investigated using powder X-ray diffraction, neutron diffraction, − and X-ray data collected on single crystals . It was established that solid solutions have a crystal structure similar to NdBa 2 Cu 3 O 7 phase in which Ba atoms can be substituted by Nd and additional oxygen atoms occupy normally vacant sites between Cu−O chains.…”