Acta Crystallographica Section A

Foundations of Crystallography

Volume 60, Part 4 (July 2004)

research papers

Acta Cryst. (2004). A60, 318-321 [ doi:10.1107/S0108767304012188 ]

U₄O₉: atoms in general sites giving the hkl extinctions of special sites

N. C. Popa and B. T. M. Willis

Abstract: In U₄O₉, most of the atoms are in general 48-fold [48(e)] sites of the space group I $\bar4$ 3d and yet the hkl reflections obey the extinction rules for atoms occupying special 12-fold [12(b)] sites. An explanation is given for this effect, which can be generalized to any space group.

Keywords: special reflection conditions; uranium oxide; systematic absences.