Crystal Structure of Tetragonal YBa2Cu3-δCoδO7-γ (δ=0, 0.3)

Abstract
Crystal structures of tetragonal YBa2Cu2.7Co0.3O7-γ and tetragonal YBa2Cu3O7-γ are determined by X-ray and TOF neutron powder diffractometries. Structural parameters are obtained by the Rietveld profile refinement method. In YBa2Cu2.7Co0.3O7-γ', cobalt atoms preferentially occupy one of the copper sites at 1a(0 0 0) rather than the 2g(0 0 z) site with z∼0.36. The lattice constants are a = 3.8644(2)Å and c = 11.7881(9)Å for the quenched YBa2Cu3O6.15 and a = 3.8752(2)Å and c = 11.6851(9)Å for the furnace-cooled YBa2Cu2.7Co0.3O6.81.