Acta Cryst. (2009). E65, i49-i50  [ doi:10.1107/S1600536809020467 ]

Y_0.76Ho_0.24FeGe₂O₇: a new member of thortveitite-like layered compounds

I. Rosales, E. Chavira, E. Orozco and L. Bucio

Abstract: Y_0.76Ho_0.24FeGe₂O₇ (yttrium holmium iron digermanate) was synthesized by solid-state reaction at 1573 K. This thortveitite-like compound presents a crystallographic group-subgroup isotranslational (klassengleiche) relation with some other pyrogermanates, such as FeInGe₂O₇, In_1.08Gd_0.92Ge₂O₇ and InYGe₂O₇, which are configurationally isotypic with the Sc₂Si₂O₇ thortveitite structure first reported by Zachariasen [(1930). Z. Kristallogr. 73, 1-6]. Holmium cations share with yttrium the 4f Wyckoff position at the center of a seven-coordinated pentagonal bipyramid, while Fe atoms also occupy one site with Wyckoff position 4f at the center of the octahedron. All these sites have the point symmetry C₁. Two types of Ge₂O₇ diorthogroups with point symmetry C_1h are present in the structure, each one of them defining a layer type which alternates with the other. These diorthogroups have their tetrahedral groups in an eclipsed conformation.

Online 6 June 2009

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