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All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on Na2Sr3As4 by Materials Project

Na2Sr3As4 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are two inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded in a distorted trigonal non-coplanar geometry to three As2- atoms. There are a spread of Na–As bond distances ranging from 2.97–3.19 Å. In the second Na1+ site, Na1+ is bonded to four As2- atoms to form distorted NaAs4 tetrahedra that share corners with three equivalent SrAs5 square pyramids, corners with two equivalent NaAs4 tetrahedra, and edges with two equivalent SrAs5 square pyramids. There are a spread of Na–As bond distances ranging from 2.91–3.15 Å. There are three inequivalent Sr2+ sites. In the first Sr2+ site, Sr2+ is bonded in a 7-coordinate geometry to seven As2- atoms. There are a spread of Sr–As bond distances ranging from 3.12–3.65 Å. In the second Sr2+ site, Sr2+ is bonded in a 6-coordinate geometry to six As2- atoms. There are a spread of Sr–As bond distances ranging from 3.02–3.22 Å. In the third Sr2+ site, Sr2+ is bonded to five As2- atoms to form distorted SrAs5 square pyramids that share corners with two equivalent SrAs5 square pyramids, corners with three equivalent NaAs4 tetrahedra, an edgeedge with one SrAs5 square pyramid, and edges with two equivalent NaAs4 tetrahedra. There are a spread of Sr–As bond distances ranging from 3.07–3.54 Å. There are four inequivalent As2- sites. In the first As2- site, As2- is bonded in a 8-coordinate geometry to three Na1+ and five Sr2+ atoms. In the second As2- site, As2- is bonded in a 7-coordinate geometry to two Na1+, four Sr2+, and one As2- atom. The As–As bond length is 2.59 Å. In the third As2- site, As2- is bonded in a 8-coordinate geometry to two Na1+, five Sr2+, and one As2- atom. The As–As bond length is 2.51 Å. In the fourth As2- site, As2- is bonded in a 6-coordinate geometry to four Sr2+ and two As2- atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

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.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Na2Sr3As4 by Materials Project

Na2Sr3As4 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are two inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded to five As2- atoms to form distorted corner-sharing NaAs5 square pyramids. There are a spread of Na–As bond distances ranging from 2.96–3.38 Å. In the second Na1+ site, Na1+ is bonded in a 6-coordinate geometry to six As2- atoms. There are a spread of Na–As bond distances ranging from 3.08–3.25 Å. There are three inequivalent Sr2+ sites. In the first Sr2+ site, Sr2+ is bonded in a 7-coordinate geometry to seven As2- atoms. There are a spread of Sr–As bond distances ranging from 3.23–3.78 Å. In the second Sr2+ site, Sr2+ is bonded in a 7-coordinate geometry to seven As2- atoms. There are a spread of Sr–As bond distances ranging from 3.24–3.79 Å. In the third Sr2+ site, Sr2+ is bonded in a 6-coordinate geometry to six As2- atoms. There are a spread of Sr–As bond distances ranging from 3.08–3.24 Å. There are four inequivalent As2- sites. In the first As2- site, As2- is bonded in a 8-coordinate geometry to three Na1+, four Sr2+, and one As2- atom. The As–As bond length is 2.54 Å. In the second As2- site, As2- is bonded in a 9-coordinate geometry to two Na1+, six Sr2+, and one As2- atom. The As–As bond length is 2.61 Å. In the third As2- site, As2- is bonded in a 9-coordinate geometry to three Na1+, five Sr2+, and one As2- atom. The As–As bond length is 2.57 Å. In the fourth As2- site, As2- is bonded in a 9-coordinate geometry to three Na1+, five Sr2+, and one As2- atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Na(SrAs)4 by Materials Project

Na(SrAs)4 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. Na1+ is bonded to five As+2.25- atoms to form NaAs5 square pyramids that share corners with six equivalent SrAs7 pentagonal bipyramids, corners with two equivalent NaAs5 square pyramids, and faces with four equivalent SrAs7 pentagonal bipyramids. There are a spread of Na–As bond distances ranging from 2.99–3.41 Å. There are two inequivalent Sr2+ sites. In the first Sr2+ site, Sr2+ is bonded in a 6-coordinate geometry to six As+2.25- atoms. There are a spread of Sr–As bond distances ranging from 3.07–3.29 Å. In the second Sr2+ site, Sr2+ is bonded to seven As+2.25- atoms to form distorted SrAs7 pentagonal bipyramids that share corners with six equivalent SrAs7 pentagonal bipyramids, corners with three equivalent NaAs5 square pyramids, edges with two equivalent SrAs7 pentagonal bipyramids, faces with three equivalent SrAs7 pentagonal bipyramids, and faces with two equivalent NaAs5 square pyramids. There are a spread of Sr–As bond distances ranging from 3.18–3.47 Å. There are three inequivalent As+2.25- sites. In the first As+2.25- site, As+2.25- is bonded in a 9-coordinate geometry to two equivalent Na1+, six Sr2+, and one As+2.25- atom. The As–As bond length is 2.54 Å. In the second As+2.25- site, As+2.25- is bonded in a 8-coordinate geometry to one Na1+, six Sr2+, and one As+2.25- atom. In the third As+2.25- site, As+2.25- is bonded in a 8-coordinate geometry to one Na1+ and seven Sr2+ atoms.

36 MATERIALS SCIENCE↗