Materials Data on Rb(GeAs)3 by Materials Project

Abstract

Rb(GeAs)3 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. Rb1+ is bonded in a 6-coordinate geometry to six As3- atoms. There are a spread of Rb–As bond distances ranging from 3.46–3.93 Å. There are three inequivalent Ge+2.67+ sites. In the first Ge+2.67+ site, Ge+2.67+ is bonded to four As3- atoms to form corner-sharing GeAs4 tetrahedra. There are a spread of Ge–As bond distances ranging from 2.45–2.50 Å. In the second Ge+2.67+ site, Ge+2.67+ is bonded in a distorted trigonal non-coplanar geometry to three As3- atoms. There are one shorter (2.52 Å) and two longer (2.53 Å) Ge–As bond lengths. In the third Ge+2.67+ site, Ge+2.67+ is bonded in a water-like geometry to two equivalent As3- atoms. Both Ge–As bond lengths are 2.56 Å. There are three inequivalent As3- sites. In the first As3- site, As3- is bonded to three equivalent Rb1+ and three Ge+2.67+ atoms to form distorted AsRb3Ge3 octahedra that share corners with two equivalent AsRb2Ge3 square pyramids, edges with four equivalent AsRb3Ge3 octahedra, and edges with three equivalent AsRb2Ge3 square pyramids. In the second As3- site, As3- is bonded to two equivalent Rb1+ and three Ge+2.67+ atoms to form distorted AsRb2Ge3 square pyramids that share corners with two equivalent AsRb3Ge3 octahedra, edges with three equivalent AsRb3Ge3 octahedra, and edges with two equivalent AsRb2Ge3 square pyramids. The corner-sharing octahedral tilt angles are 18°. In the third As3- site, As3- is bonded in a rectangular see-saw-like geometry to one Rb1+ and three Ge+2.67+ atoms.