Crystal structure of the high-TcsuperconductorBa2YCu3O7+xusing neutron diffraction

The crystal structure of the high-$T_c$ superconductor ${\mathrm{Ba}}_2\mathrm{Y}{\mathrm{Cu}}_3{\mathrm{O}}_{7+x}$ has been studied using neutron diffraction. This compound has an orthorhombic structure with space group Pmmm and lattice parameters $a=3.8132\mathrm{}$ Å, $b=3.8774\mathrm{}$ Å, and $c=11.653\mathrm{}$ Å. We found an occupancy of 0.1 for oxygen atoms at the $1b$ site and a total number of oxygen atom per unit cell of 7.1. The high quality of the sample used may be associated with the partial occupation at the $1b$ site by oxygen atoms.