Materials Data on CaU2Si2O17 by Materials Project

Abstract

(CaU2(SiO8)2)2O2 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional and consists of four water molecules and one CaU2(SiO8)2 framework. In the CaU2(SiO8)2 framework, Ca is bonded in a 4-coordinate geometry to six O atoms. There are a spread of Ca–O bond distances ranging from 2.25–3.02 Å. There are two inequivalent U sites. In the first U site, U is bonded to seven O atoms to form distorted UO7 pentagonal bipyramids that share corners with three SiO4 tetrahedra, edges with two equivalent UO7 pentagonal bipyramids, and an edgeedge with one SiO4 tetrahedra. There are a spread of U–O bond distances ranging from 1.81–2.54 Å. In the second U site, U is bonded to seven O atoms to form distorted UO7 pentagonal bipyramids that share corners with three SiO4 tetrahedra, edges with two equivalent UO7 pentagonal bipyramids, and an edgeedge with one SiO4 tetrahedra. There are a spread of U–O bond distances ranging from 1.87–2.51 Å. There are two inequivalent Si sites. In the first Si site, Si is bonded to four O atoms to form SiO4 tetrahedra that share corners with three UO7 pentagonal bipyramids and an edgeedge with one UO7 pentagonal bipyramid. There are a spread of Si–O bond distances ranging from 1.58–1.87 Å. In the second Si site, Si is bonded to four O atoms to form SiO4 tetrahedra that share corners with three UO7 pentagonal bipyramids and an edgeedge with one UO7 pentagonal bipyramid. There are a spread of Si–O bond distances ranging from 1.65–1.67 Å. There are sixteen inequivalent O sites. In the first O site, O is bonded in a bent 150 degrees geometry to one Ca and 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 bent 150 degrees geometry to one Ca and one U atom. In the fourth O site, O is bonded in a distorted bent 150 degrees geometry to one Ca and one U atom. In the fifth O site, O is bonded in a 1-coordinate geometry to two U and one Si atom. In the sixth O site, O is bonded in a 1-coordinate geometry to two U and one Si atom. In the seventh O site, O is bonded in a 1-coordinate geometry to two U and one Si atom. In the eighth O site, O is bonded in a 1-coordinate geometry to two U and one Si atom. In the ninth O site, O is bonded in a bent 150 degrees geometry to one U and one Si atom. In the tenth O site, O is bonded in a bent 150 degrees geometry to one U and one Si atom. In the eleventh 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 1.28 Å. In the twelfth O site, O is bonded in a distorted bent 150 degrees geometry to one Ca and one Si atom. In the thirteenth O site, O is bonded in a distorted bent 120 degrees geometry to one Ca and one O atom. The O–O bond length is 1.23 Å. In the fourteenth O site, O is bonded in a single-bond geometry to one O atom. In the fifteenth O site, O is bonded in a distorted single-bond geometry to one Ca and one O atom. The O–O bond length is 1.23 Å. In the sixteenth O site, O is bonded in a single-bond geometry to one O atom.