Materials Data on NaSr2(SnAs)6 by Materials Project

Abstract

NaSr2(SnAs)6 crystallizes in the monoclinic C2/m space group. The structure is two-dimensional and consists of one NaSr2(SnAs)6 sheet oriented in the (0, 0, 1) direction. Na1+ is bonded to six equivalent As3- atoms to form NaAs6 octahedra that share edges with six equivalent SrAs6 octahedra. All Na–As bond lengths are 3.16 Å. Sr2+ is bonded to six equivalent As3- atoms to form SrAs6 octahedra that share edges with three equivalent NaAs6 octahedra and edges with three equivalent SrAs6 octahedra. All Sr–As bond lengths are 3.17 Å. There are two inequivalent Sn+2.17+ sites. In the first Sn+2.17+ site, Sn+2.17+ is bonded in a distorted T-shaped geometry to three equivalent As3- atoms. There are two shorter (2.78 Å) and one longer (2.79 Å) Sn–As bond lengths. In the second Sn+2.17+ site, Sn+2.17+ is bonded in a distorted T-shaped geometry to three equivalent As3- atoms. All Sn–As bond lengths are 2.78 Å. As3- is bonded to one Na1+, two equivalent Sr2+, and three Sn+2.17+ atoms to form a mixture of corner and edge-sharing AsNaSr2Sn3 octahedra. The corner-sharing octahedral tilt angles are 0°.