Materials Data on Sr4TiAs4 by Materials Project

Abstract

Sr4TiAs4 crystallizes in the cubic P-43n space group. The structure is three-dimensional. there are two inequivalent Sr2+ sites. In the first Sr2+ site, Sr2+ is bonded to six As3- atoms to form distorted SrAs6 octahedra that share corners with six equivalent SrAs6 octahedra, corners with three equivalent TiAs4 tetrahedra, edges with twelve SrAs6 octahedra, and a faceface with one TiAs4 tetrahedra. The corner-sharing octahedral tilt angles are 16°. There are three shorter (3.20 Å) and three longer (3.41 Å) Sr–As bond lengths. In the second Sr2+ site, Sr2+ is bonded to six As3- atoms to form distorted SrAs6 octahedra that share corners with six SrAs6 octahedra, corners with three TiAs4 tetrahedra, edges with twelve SrAs6 octahedra, and a faceface with one TiAs4 tetrahedra. The corner-sharing octahedra tilt angles range from 12–20°. There are a spread of Sr–As bond distances ranging from 3.17–3.43 Å. There are two inequivalent Ti4+ sites. In the first Ti4+ site, Ti4+ is bonded to four equivalent As3- atoms to form TiAs4 tetrahedra that share corners with twelve equivalent SrAs6 octahedra and faces with four equivalent SrAs6 octahedra. The corner-sharing octahedral tilt angles are 53°. All Ti–As bond lengths are 2.47 Å. In the second Ti4+ site, Ti4+ is bonded to four equivalent As3- atoms to form TiAs4 tetrahedra that share corners with twelve SrAs6 octahedra and faces with four equivalent SrAs6 octahedra. The corner-sharing octahedra tilt angles range from 46–55°. All Ti–As bond lengths are 2.47 Å. There are two inequivalent As3- sites. In the first As3- site, As3- is bonded in a 7-coordinate geometry to six Sr2+ and one Ti4+ atom. In the second As3- site, As3- is bonded in a 7-coordinate geometry to six Sr2+ and one Ti4+ atom.