Crystal Structure by Neutron Diffraction and the Antiferroelectric Phase Transition in Copper Formate Tetrahydrate

Abstract

The hydrogen positions in the crystal structure of copper formate tetrahydrate have been determined, and some new data on the antiferroelectric phase transition at −38.9°C are presented. It is shown that the orientation of the water molecules is disordered in such a way as to permit all possible short 0–0 contacts to be hydrogen bonded all of the time. The disorder is similar to that observed in ice. The phase transition probably occurs because of hydrogen motion.