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Delphine Phanon, Bachir Bentria, Erwann Jeanneau, Djamal Benbertal, Alain Mosset, Isabelle Gautier-Luneau
Crystal structure of M(IO3)2 metal iodates, twinned bypseudo-merohedry, with MII: MgII, MnII, CoII, NiII and ZnII
Keywords: Twinning by pseudo-merohedry, Iodate, NLO materials, X-ray diffraction, Single crystal structure analysis
The non-centrosymmetric materials Zn(IO3)2, Mn(IO3)2, Co(IO3)2, Mg(IO3)2 and β-Ni(IO3)2 have been synthesised by evaporation of nitric acid solutions of metal salts and lithium iodate. All these compounds are isostructural and their structures were characterised both by X-ray diffraction on powder and single crystals. They crystallise in the monoclinic crystal system, space-group type P21 (no. 4) with a pseudo-hexagonal lattice, as shown by the lattice parameters of Mn(IO3)2 for example: a = 11.247(1) Å, b = 5.045(1) Å, c = 11.246(1) Å, β = 120.02(1)°, V = 552.5(1) Å3, Z = 4. This monoclinic symmetry with a ∼ c and β ∼ 120° leads to a three-individual pseudo-hexagonal twin by pseudo-merohedry. The structure reveals a three-dimensional network in which each octahedrally coordinated cation is linked to ten others via iodate bridges. All these metal iodates generate second harmonics.
Zeitschrift für Kristallographie, Oldenbourg Wissenschaftsverlag
Print ISSN: 0044-2968
Volume: 221, 09/2006
Pages: 635 - 642