Acta Crystallographica Section C

Crystal Structure Communications

Volume 64, Part 8 (August 2008)

inorganic compounds

Acta Cryst. (2008). C64, i76-i78 [ doi:10.1107/S0108270108020386 ]

Partial Cu occupancy in uranium copper diantimonide, UCu_0.60(4)Sb₂

E. Ringe and J. A. Ibers

Abstract: The title compound, UCu_0.60(4)Sb₂, crystallizes in the tetragonal space group P4/nmm. The U atom and one independent Sb atom have 4mm site symmetry, whereas the Cu atom and the other Sb atom have $\overline{4}$ 2m site symmetry. Zigzag USb sheets stack perpendicular to the c axis. These sheets are separated by square-planar nets of Sb atoms and Cu atoms. The length of the a axis for UCu_xSb₂ is invariant to x, whereas there is a linear relationship between Cu occupancy and the length of the c axis (following Vegard's Law) that holds for x between 0 and 1. This is explained in terms of the crystal structure.

Formula: UCu_0.60(4)Sb₂ at 100 and 120 K