Time-of-flight neutron diffraction studies on the different phases of CsOH, H₂O

Neutron diffraction studies on the two dimensional ice CsOH, H₂O were performed at the High Resolution Powder Diffractometer at the spallation source ISIS in England. The structure at the highest temperature comprises an O (and H) disorder perpendicular to the O₂H₃^- nets as well as an H disorder along an O-O connection line within the nets. The room temperature phase comprises ordered, corrugated nets, very likely built of ordered groups of OH^- and H₂O. The O order disorder transition can be assigned to the phase transition at 340 K. For a deuterated sample the different behavior of the OD^- and the D₂O group is determined. The OD^- group must be described by a model with O off the threefold axis. O-D⋯O bridges of different strengths result.