Materials Data on K2UAs2O9 by Materials Project

Abstract

K2UAs2O9 crystallizes in the orthorhombic Pmmn space group. The structure is three-dimensional. there are two inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a 10-coordinate geometry to ten O2- atoms. There are a spread of K–O bond distances ranging from 2.79–3.29 Å. In the second K1+ site, K1+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of K–O bond distances ranging from 2.94–3.23 Å. U6+ is bonded to six O2- atoms to form UO6 octahedra that share corners with four AsO4 tetrahedra. There are a spread of U–O bond distances ranging from 1.82–2.31 Å. There are two inequivalent As5+ sites. In the first As5+ site, As5+ is bonded to four O2- atoms to form AsO4 tetrahedra that share corners with two equivalent UO6 octahedra and a cornercorner with one AsO4 tetrahedra. The corner-sharing octahedral tilt angles are 50°. There are a spread of As–O bond distances ranging from 1.66–1.81 Å. In the second As5+ site, As5+ is bonded to four O2- atoms to form AsO4 tetrahedra that share corners with two equivalent UO6 octahedra and a cornercorner with one AsO4 tetrahedra. The corner-sharing octahedral tilt angles are 47°. There are a spread of As–O bond distances ranging from 1.67–1.82 Å. There are seven inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two equivalent K1+ and two equivalent As5+ atoms. In the second O2- site, O2- is bonded in a distorted single-bond geometry to one K1+ and one U6+ atom. In the third O2- site, O2- is bonded in a 2-coordinate geometry to two K1+, one U6+, and one As5+ atom. In the fourth O2- site, O2- is bonded in a distorted single-bond geometry to three K1+ and one As5+ atom. In the fifth O2- site, O2- is bonded in a 2-coordinate geometry to two K1+, one U6+, and one As5+ atom. In the sixth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two equivalent K1+ and two equivalent As5+ atoms. In the seventh O2- site, O2- is bonded in a distorted single-bond geometry to three K1+ and one As5+ atom.