Space group of the spinel structure: A neutron diffraction study of MgAl₂O₄

It has been suggested that the crystal structure of cubic spinel compounds should be referred to the non-centrosymmetric space group F43m instead of the customary space group Fd3m. The need for the new assignment arises from the possibility of an off-centre displacement of the octahedrally coordinated cations. The authors have examined MgAl2O4 carefully by powder neutron diffraction and find no evidence for such a displacement: it is concluded that the correct space group for this material is Fd3m.