Materials Data on Ba3(SiAs2)2 by Materials Project
Ba3(SiAs2)2 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. there are three inequivalent Ba2+ sites. In the first Ba2+ site, Ba2+ is bonded to six As+1.50- atoms to form BaAs6 octahedra that share corners with four BaAs6 octahedra, corners with four equivalent SiSiAs3 tetrahedra, edges with nine BaAs6 octahedra, and edges with two equivalent SiSiAs3 tetrahedra. The corner-sharing octahedra tilt angles range from 8–16°. There are a spread of Ba–As bond distances ranging from 3.31–3.44 Å. In the second Ba2+ site, Ba2+ is bonded to six As+1.50- atoms to form BaAs6 octahedra that share corners with four BaAs6 octahedra, corners with eight equivalent SiSiAs3 tetrahedra, and edges with nine BaAs6 octahedra. The corner-sharing octahedral tilt angles are 8°. There are a spread of Ba–As bond distances ranging from 3.33–3.56 Å. In the third Ba2+ site, Ba2+ is bonded to six As+1.50- atoms to form BaAs6 octahedra that share corners with four BaAs6 octahedra, corners with six equivalent SiSiAs3 tetrahedra, edges with eight BaAs6 octahedra, and edges with two equivalent SiSiAs3 tetrahedra. The corner-sharing octahedra tilt angles range from 8–16°. There are a spread of Ba–As bond distances ranging from 3.28–3.61 Å. Si is bonded to one Si and three As+1.50- atoms to form SiSiAs3 tetrahedra that share corners with three AsBa4Si2 octahedra, corners with nine BaAs6 octahedra, edges with two BaAs6 octahedra, and an edgeedge with one SiSiAs3 tetrahedra. The corner-sharing octahedra tilt angles range from 16–81°. The Si–Si bond length is 2.41 Å. There are one shorter (2.38 Å) and two longer (2.44 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 Ba2+ and two equivalent Si atoms to form distorted AsBa4Si2 octahedra that share corners with eight AsBa4Si2 octahedra, corners with two equivalent SiSiAs3 tetrahedra, and edges with eight AsBa4Si2 octahedra. The corner-sharing octahedra tilt angles range from 5–97°. In the second As+1.50- site, As+1.50- is bonded to five Ba2+ and one Si atom to form AsBa5Si octahedra that share corners with seven AsBa4Si2 octahedra, a cornercorner with one SiSiAs3 tetrahedra, and edges with ten AsBa4Si2 octahedra. The corner-sharing octahedra tilt angles range from 5–94°.