NEUTRON POWDER DIFFRACTION STUDY ON HIGHLY DEUTERATED CA(IO3)(2).D2O

Neutron powder diffraction experiments were performed on highly deuter ated calcium iodate monohydrate (bruggenite) to examine possible H/D e nrichment effects. The title compound is built up of distorted CaO8 qu adratic antiprisms. The iodate ions form layers parallel to (100), rev ealing relatively short interionic I ... O distances of 3.02 and 2.90 Angstrom. The water molecules are trigonally planar coordinated (2 IO3 -, 1 Ca2+, site symmetry C-1), forming asymmetric hydrogen bonds of di fferent strengths to adjacent iodate ions. Deviation from random distr ibution of the H atoms has been established.