Topotaxy in the oxidation of valentinite,Sb2O3, to cervantite,Sb2O4

The oxidation of orthorhombic Sb₂O₃, valentinite, to orthorhombic Sb₂O₄, cervantite, has been shown by single crystal x-ray diffraction techniques to be a topotactic reaction. The orientation relationships between the two lattices have been determined by making use of a hybrid crystal. It has been found that the individual axes in the two oxides are parallel. The two crystal structures have been compared in the appropriate orientation and their close similarity has been established. The shifts of the individual atoms in valentinite during the process of oxidation have been calculated to be not more than 0·6 Å. It has been established that the reduction of cervantite to valentinite also takes place topotactically.