Materials Data on MgU2(AsO8)2 by Materials Project

Abstract

MgO4(UAsO6)2 crystallizes in the monoclinic C2/m space group. The structure is two-dimensional and consists of two MgO4 clusters and two UAsO6 sheets oriented in the (1, 0, 0) direction. In each MgO4 cluster, Mg is bonded in a distorted square co-planar geometry to four equivalent O atoms. All Mg–O bond lengths are 2.03 Å. O is bonded in a single-bond geometry to one Mg atom. In each UAsO6 sheet, U is bonded to seven O atoms to form distorted UO7 pentagonal bipyramids that share corners with three equivalent AsO4 tetrahedra, edges with two equivalent UO7 pentagonal bipyramids, and an edgeedge with one AsO4 tetrahedra. There are a spread of U–O bond distances ranging from 1.79–2.54 Å. As is bonded to four O atoms to form AsO4 tetrahedra that share corners with three equivalent UO7 pentagonal bipyramids and an edgeedge with one UO7 pentagonal bipyramid. There are a spread of As–O bond distances ranging from 1.69–1.74 Å. There are five inequivalent O sites. In the first O site, O is bonded in a single-bond geometry to one U atom. In the second O site, O is bonded in a single-bond geometry to one As atom. In the third O site, O is bonded in a 3-coordinate geometry to two equivalent U and one As atom. In the fourth O site, O is bonded in a single-bond geometry to one U atom. In the fifth O site, O is bonded in a bent 150 degrees geometry to one U and one As atom.