title: A tetragonal polymorph of caesium hydroxide monohydrate, CsOH x H2O, from X-ray powder data.
abstract: Tetragonal caesium hydroxide monohydrate, CsOH x H(2)O, a clathrate hydrate, is a polymorph of three known hexagonal or pseudo-hexagonal modifications. It was obtained as a by-product in a high-pressure experiment. Whether it is a high-pressure polymorph, however, remains to be verified. The Cs atoms are situated in cavities of the form of a bicapped pentagonal prism, within an infinite three-dimensional hydrogen-bonded oxygen framework that is locally identical to layers found in the hexagonal modifications. The Cs atom and one of the two H atoms are at sites with (macro)4m2 symmetry, the O atom has mm site symmetry and the second H atom has 2/m symmetry.
authors.affiliation: Laboratoire de Cristallographie, Université de Genève, 24, quai Ernest-Ansermet, CH-1211 Genève 4, Switzerland. radovan.cerny@cryst.unige.ch
authors.forename: Radovan
authors.initials: R
authors.lastname: Cerný
authors.forename: Vincent
authors.initials: V
authors.lastname: Favre-Nicolin
authors.forename: Bernard
authors.initials: B
authors.lastname: Bertheville