DOE OSTI2020
SrAs3 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. Sr2+ is bonded to eight As+0.67- atoms to form distorted SrAs8 hexagonal bipyramids that share corners with six equivalent SrAs8 hexagonal bipyramids, corners with five equivalent AsSr4As2 pentagonal pyramids, corners with six equivalent AsSrAs3 tetrahedra, edges with four equivalent SrAs8 hexagonal bipyramids, an edgeedge with one AsSrAs3 tetrahedra, and a faceface with one SrAs8 hexagonal bipyramid. There are a spread of Sr–As bond distances ranging from 3.15–3.53 Å. There are three inequivalent As+0.67- sites. In the first As+0.67- site, As+0.67- is bonded to one Sr2+ and three As+0.67- atoms to form distorted AsSrAs3 tetrahedra that share corners with six equivalent SrAs8 hexagonal bipyramids, corners with six equivalent AsSr4As2 pentagonal pyramids, and an edgeedge with one SrAs8 hexagonal bipyramid. There are two shorter (2.48 Å) and one longer (2.52 Å) As–As bond lengths. In the second As+0.67- site, As+0.67- is bonded to four equivalent Sr2+ and two As+0.67- atoms to form distorted AsSr4As2 pentagonal pyramids that share corners with five equivalent SrAs8 hexagonal bipyramids, corners with four equivalent AsSr4As2 pentagonal pyramids, corners with six equivalent AsSrAs3 tetrahedra, and edges with four equivalent AsSr4As2 pentagonal pyramids. The As–As bond length is 2.51 Å. In the third As+0.67- site, As+0.67- is bonded in a 5-coordinate geometry to three equivalent Sr2+ and two As+0.67- atoms. The As–As bond length is 2.50 Å.