DOI: 10.17188/1676867
title: Materials Data on Na7U5(SiO6)4 by Materials Project

description: Na7U5(SiO6)4 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. there are four inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded to six O2- atoms to form NaO6 octahedra that share corners with four UO7 pentagonal bipyramids, corners with two equivalent SiO4 tetrahedra, and edges with two equivalent UO6 octahedra. There are a spread of Na–O bond distances ranging from 2.35–2.64 Å. In the second Na1+ site, Na1+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Na–O bond distances ranging from 2.40–3.00 Å. In the third Na1+ site, Na1+ is bonded in a 4-coordinate geometry to four O2- atoms. There are a spread of Na–O bond distances ranging from 2.41–2.49 Å. In the fourth Na1+ site, Na1+ is bonded in a 4-coordinate geometry to four O2- atoms. There are a spread of Na–O bond distances ranging from 2.32–2.43 Å. There are three inequivalent U5+ sites. In the first U5+ site, U5+ is bonded to six O2- atoms to form UO6 octahedra that share corners with two equivalent UO7 pentagonal bipyramids, corners with four SiO4 tetrahedra, and edges with two equivalent NaO6 octahedra. There are a spread of U–O bond distances ranging from 2.18–2.26 Å. In the second U5+ site, U5+ is bonded to seven O2- atoms to form distorted UO7 pentagonal bipyramids that share a cornercorner with one NaO6 octahedra, a cornercorner with one UO6 octahedra, corners with three SiO4 tetrahedra, edges with two equivalent UO7 pentagonal bipyramids, and an edgeedge with one SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 48–61°. There are a spread of U–O bond distances ranging from 1.92–2.55 Å. In the third U5+ site, U5+ is bonded to seven O2- atoms to form distorted UO7 pentagonal bipyramids that share a cornercorner with one NaO6 octahedra, corners with three SiO4 tetrahedra, edges with two equivalent UO7 pentagonal bipyramids, and an edgeedge with one SiO4 tetrahedra. The corner-sharing octahedral tilt angles are 58°. There are a spread of U–O bond distances ranging from 1.91–2.57 Å. There are two inequivalent Si4+ sites. In the first Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share a cornercorner with one NaO6 octahedra, a cornercorner with one UO6 octahedra, corners with three UO7 pentagonal bipyramids, and an edgeedge with one UO7 pentagonal bipyramid. The corner-sharing octahedra tilt angles range from 43–68°. There are a spread of Si–O bond distances ranging from 1.63–1.65 Å. In the second Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share a cornercorner with one UO6 octahedra, corners with three UO7 pentagonal bipyramids, and an edgeedge with one UO7 pentagonal bipyramid. The corner-sharing octahedral tilt angles are 50°. There are a spread of Si–O bond distances ranging from 1.62–1.66 Å. There are twelve inequivalent O2- sites. In the first O2- site, O2- is bonded in a 4-coordinate geometry to two Na1+, one U5+, and one Si4+ atom. In the second O2- site, O2- is bonded in a 1-coordinate geometry to two U5+ and one Si4+ atom. In the third O2- site, O2- is bonded in a 1-coordinate geometry to two U5+ and one Si4+ atom. In the fourth O2- site, O2- is bonded in a 3-coordinate geometry to two Na1+, one U5+, and one Si4+ atom. In the fifth O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Na1+, one U5+, and one Si4+ atom. In the sixth O2- site, O2- is bonded in a 1-coordinate geometry to one Na1+, two U5+, and one Si4+ atom. In the seventh O2- site, O2- is bonded in a 4-coordinate geometry to two Na1+, one U5+, and one Si4+ atom. In the eighth O2- site, O2- is bonded in a 1-coordinate geometry to two U5+ and one Si4+ atom. In the ninth O2- site, O2- is bonded in a 4-coordinate geometry to two Na1+ and two U5+ atoms. In the tenth O2- site, O2- is bonded in a 3-coordinate geometry to two Na1+ and one U5+ atom. In the eleventh O2- site, O2- is bonded in a 4-coordinate geometry to three Na1+ and one U5+ atom. In the twelfth O2- site, O2- is bonded in a 3-coordinate geometry to two Na1+ and one U5+ atom.