Materials Data on SrYbSi4N7 by Materials Project

Abstract

SrYbSi4N7 crystallizes in the hexagonal P6_3mc space group. The structure is three-dimensional. Sr2+ is bonded to twelve N3- atoms to form distorted SrN12 cuboctahedra that share corners with twelve equivalent SrN12 cuboctahedra, edges with twelve SiN4 tetrahedra, and faces with four equivalent YbN6 octahedra. There are a spread of Sr–N bond distances ranging from 2.92–3.16 Å. Yb3+ is bonded to six N3- atoms to form YbN6 octahedra that share corners with twelve SiN4 tetrahedra and faces with four equivalent SrN12 cuboctahedra. There are three shorter (2.33 Å) and three longer (2.37 Å) Yb–N bond lengths. There are two inequivalent Si4+ sites. In the first Si4+ site, Si4+ is bonded to four N3- atoms to form SiN4 tetrahedra that share corners with three equivalent YbN6 octahedra, corners with six equivalent SiN4 tetrahedra, and edges with three equivalent SrN12 cuboctahedra. The corner-sharing octahedral tilt angles are 57°. There is three shorter (1.70 Å) and one longer (1.86 Å) Si–N bond length. In the second Si4+ site, Si4+ is bonded to four N3- atoms to form SiN4 tetrahedra that share corners with three equivalent YbN6 octahedra, corners with six SiN4 tetrahedra, and edges with three equivalent SrN12 cuboctahedra. The corner-sharing octahedra tilt angles range from 58–63°. There is three shorter (1.72 Å) and one longer (1.99 Å) Si–N bond length. There are three inequivalent N3- sites. In the first N3- site, N3- is bonded in a tetrahedral geometry to four Si4+ atoms. In the second N3- site, N3- is bonded in a 3-coordinate geometry to two equivalent Sr2+, one Yb3+, and two equivalent Si4+ atoms. In the third N3- site, N3- is bonded in a distorted trigonal planar geometry to two equivalent Sr2+, one Yb3+, and two Si4+ atoms.