DOE OSTI2020
Rb3U2Ge2O11 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are three inequivalent Rb1+ sites. In the first Rb1+ site, Rb1+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Rb–O bond distances ranging from 2.87–3.40 Å. In the second Rb1+ site, Rb1+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Rb–O bond distances ranging from 2.81–3.49 Å. In the third Rb1+ site, Rb1+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Rb–O bond distances ranging from 2.90–3.42 Å. There are three inequivalent U+5.50+ sites. In the first U+5.50+ site, U+5.50+ is bonded to six O2- atoms to form UO6 octahedra that share corners with two UO6 octahedra and corners with four GeO4 tetrahedra. The corner-sharing octahedra tilt angles range from 37–43°. There are a spread of U–O bond distances ranging from 2.03–2.25 Å. In the second U+5.50+ site, U+5.50+ is bonded to six O2- atoms to form UO6 octahedra that share corners with two equivalent UO6 octahedra and corners with two equivalent GeO4 tetrahedra. The corner-sharing octahedral tilt angles are 43°. There are a spread of U–O bond distances ranging from 1.89–2.28 Å. In the third U+5.50+ site, U+5.50+ is bonded to six O2- atoms to form UO6 octahedra that share corners with two equivalent UO6 octahedra and corners with two equivalent GeO4 tetrahedra. The corner-sharing octahedral tilt angles are 37°. There are a spread of U–O bond distances ranging from 1.88–2.27 Å. There are two inequivalent Ge4+ sites. In the first Ge4+ site, Ge4+ is bonded to four O2- atoms to form GeO4 tetrahedra that share corners with three UO6 octahedra and a cornercorner with one GeO4 tetrahedra. The corner-sharing octahedra tilt angles range from 44–56°. There are a spread of Ge–O bond distances ranging from 1.76–1.81 Å. In the second Ge4+ site, Ge4+ is bonded to four O2- atoms to form GeO4 tetrahedra that share corners with three UO6 octahedra and a cornercorner with one GeO4 tetrahedra. The corner-sharing octahedra tilt angles range from 47–57°. There are a spread of Ge–O bond distances ranging from 1.76–1.80 Å. There are eleven inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to one Rb1+, one U+5.50+, and one Ge4+ atom. In the second O2- site, O2- is bonded in a 2-coordinate geometry to one Rb1+ and two U+5.50+ atoms. In the third O2- site, O2- is bonded in a distorted single-bond geometry to three Rb1+ and one U+5.50+ atom. In the fourth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two Rb1+ and two Ge4+ atoms. In the fifth O2- site, O2- is bonded in a 2-coordinate geometry to two Rb1+ and two U+5.50+ atoms. In the sixth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to three Rb1+, one U+5.50+, and one Ge4+ atom. In the seventh O2- site, O2- is bonded in a distorted single-bond geometry to three Rb1+ and one U+5.50+ atom. In the eighth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Rb1+, one U+5.50+, and one Ge4+ atom. In the ninth O2- site, O2- is bonded in a 2-coordinate geometry to two Rb1+, one U+5.50+, and one Ge4+ atom. In the tenth O2- site, O2- is bonded in a 2-coordinate geometry to two Rb1+, one U+5.50+, and one Ge4+ atom. In the eleventh O2- site, O2- is bonded in a 4-coordinate geometry to two Rb1+, one U+5.50+, and one Ge4+ atom.