Materials Data on NaSrAs by Materials Project
NaSrAs crystallizes in the hexagonal P-62m space group. The structure is three-dimensional. Na1+ is bonded to four As3- atoms to form NaAs4 tetrahedra that share corners with six equivalent SrAs5 square pyramids, corners with ten equivalent NaAs4 tetrahedra, edges with six equivalent SrAs5 square pyramids, and edges with two equivalent NaAs4 tetrahedra. There are two shorter (2.99 Å) and two longer (3.06 Å) Na–As bond lengths. Sr2+ is bonded to five As3- atoms to form SrAs5 square pyramids that share corners with ten equivalent SrAs5 square pyramids, corners with six equivalent NaAs4 tetrahedra, edges with six equivalent SrAs5 square pyramids, and edges with six equivalent NaAs4 tetrahedra. There are one shorter (3.27 Å) and four longer (3.31 Å) Sr–As bond lengths. There are two inequivalent As3- sites. In the first As3- site, As3- is bonded in a 9-coordinate geometry to three equivalent Na1+ and six equivalent Sr2+ atoms. In the second As3- site, As3- is bonded in a 9-coordinate geometry to six equivalent Na1+ and three equivalent Sr2+ atoms.