Materials Data on U2CuSi2O17 by Materials Project

Abstract

U2CuSi2O17 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. U is bonded to seven O atoms to form distorted UO7 pentagonal bipyramids that share a cornercorner with one CuO6 octahedra, corners with three equivalent SiO4 tetrahedra, edges with two equivalent UO7 pentagonal bipyramids, and an edgeedge with one SiO4 tetrahedra. The corner-sharing octahedral tilt angles are 49°. There are a spread of U–O bond distances ranging from 1.82–2.53 Å. Cu is bonded to six O atoms to form distorted CuO6 octahedra that share corners with two equivalent UO7 pentagonal bipyramids. There are a spread of Cu–O bond distances ranging from 1.76–2.44 Å. Si is bonded to four O atoms to form SiO4 tetrahedra that share corners with three equivalent UO7 pentagonal bipyramids and an edgeedge with one UO7 pentagonal bipyramid. There are a spread of Si–O bond distances ranging from 1.60–1.76 Å. There are nine inequivalent O sites. In the first O site, O is bonded in a distorted single-bond geometry to one U and one Cu atom. In the second O site, O is bonded in a single-bond geometry to one U and one O atom. The O–O bond length is 1.75 Å. In the third O site, O is bonded in a 1-coordinate geometry to two equivalent U and one Si atom. In the fourth O site, O is bonded in a 1-coordinate geometry to two equivalent U and one Si atom. In the fifth O site, O is bonded in a distorted bent 120 degrees geometry to one Si and one O atom. The O–O bond length is 1.35 Å. In the sixth O site, O is bonded in a bent 150 degrees geometry to one U and one Si atom. In the seventh O site, O is bonded in a single-bond geometry to one Cu atom. In the eighth O site, O is bonded in a distorted bent 120 degrees geometry to one Cu and one O atom. In the ninth O site, O is bonded in a linear geometry to two equivalent O atoms.