Materials Data on Sr3(SiAs2)2 by Materials Project
Sr3(SiAs2)2 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. there are three inequivalent Sr2+ sites. In the first Sr2+ site, Sr2+ is bonded to six As+1.50- atoms to form SrAs6 octahedra that share corners with four SrAs6 octahedra, corners with four equivalent SiSiAs3 tetrahedra, edges with nine SrAs6 octahedra, and edges with two equivalent SiSiAs3 tetrahedra. The corner-sharing octahedra tilt angles range from 4–11°. There are two shorter (3.16 Å) and four longer (3.20 Å) Sr–As bond lengths. In the second Sr2+ site, Sr2+ is bonded to six As+1.50- atoms to form SrAs6 octahedra that share corners with four SrAs6 octahedra, corners with eight equivalent SiSiAs3 tetrahedra, and edges with nine SrAs6 octahedra. The corner-sharing octahedral tilt angles are 4°. There are a spread of Sr–As bond distances ranging from 3.17–3.35 Å. In the third Sr2+ site, Sr2+ is bonded to six As+1.50- atoms to form SrAs6 octahedra that share corners with four SrAs6 octahedra, corners with six equivalent SiSiAs3 tetrahedra, edges with eight SrAs6 octahedra, and edges with two equivalent SiSiAs3 tetrahedra. The corner-sharing octahedra tilt angles range from 4–11°. There are a spread of Sr–As bond distances ranging from 3.13–3.36 Å. Si is bonded to one Si and three As+1.50- atoms to form SiSiAs3 tetrahedra that share corners with three AsSr4Si2 octahedra, corners with nine SrAs6 octahedra, edges with two SrAs6 octahedra, and an edgeedge with one SiSiAs3 tetrahedra. The corner-sharing octahedra tilt angles range from 19–82°. The Si–Si bond length is 2.37 Å. There are one shorter (2.36 Å) and two longer (2.43 Å) Si–As bond lengths. There are two inequivalent As+1.50- sites. In the first As+1.50- site, As+1.50- is bonded to four Sr2+ and two equivalent Si atoms to form distorted AsSr4Si2 octahedra that share corners with eight AsSr4Si2 octahedra, corners with two equivalent SiSiAs3 tetrahedra, and edges with eight AsSr4Si2 octahedra. The corner-sharing octahedra tilt angles range from 4–94°. In the second As+1.50- site, As+1.50- is bonded to five Sr2+ and one Si atom to form AsSr5Si octahedra that share corners with seven AsSr4Si2 octahedra, a cornercorner with one SiSiAs3 tetrahedra, and edges with ten AsSr4Si2 octahedra. The corner-sharing octahedra tilt angles range from 1–90°.