Materials Data on MgU2Si2O17 by Materials Project
MgU2Si2O17 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. Mg is bonded to six O atoms to form MgO6 octahedra that share corners with two equivalent SiO4 tetrahedra. There are two shorter (1.91 Å) and four longer (2.10 Å) Mg–O bond lengths. U is bonded in a 5-coordinate geometry to five O atoms. There are two shorter (1.81 Å) and three longer (2.25 Å) U–O bond lengths. Si is bonded to four O atoms to form SiO4 tetrahedra that share a cornercorner with one MgO6 octahedra. The corner-sharing octahedral tilt angles are 9°. There are a spread of Si–O bond distances ranging from 1.61–1.66 Å. There are seven 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 U atom. In the third O site, O is bonded in a linear geometry to one Mg and one Si atom. In the fourth O site, O is bonded in a bent 150 degrees geometry to one U and one Si atom. In the fifth O site, O is bonded in a 2-coordinate geometry to one U and one Si atom. In the sixth O site, O is bonded in a 2-coordinate geometry to one Mg and two O atoms. There is one shorter (1.35 Å) and one longer (1.73 Å) O–O bond length. In the seventh O site, O is bonded in a distorted rectangular see-saw-like geometry to four equivalent O atoms.