Materials Data on La5(SiN3)3 by Materials Project

Abstract

La5Si3N9 crystallizes in the orthorhombic Cmce space group. The structure is three-dimensional. there are four inequivalent La3+ sites. In the first La3+ site, La3+ is bonded in a 8-coordinate geometry to eight N3- atoms. There are a spread of La–N bond distances ranging from 2.47–3.12 Å. In the second La3+ site, La3+ is bonded to seven N3- atoms to form LaN7 pentagonal bipyramids that share corners with two equivalent SiN4 tetrahedra, edges with two equivalent LaN6 octahedra, and edges with four SiN4 tetrahedra. There are a spread of La–N bond distances ranging from 2.50–2.69 Å. In the third La3+ site, La3+ is bonded in a 1-coordinate geometry to seven N3- atoms. There are a spread of La–N bond distances ranging from 2.41–2.93 Å. In the fourth La3+ site, La3+ is bonded to six N3- atoms to form distorted LaN6 octahedra that share corners with six SiN4 tetrahedra, an edgeedge with one LaN6 octahedra, and edges with two equivalent LaN7 pentagonal bipyramids. There are a spread of La–N bond distances ranging from 2.41–2.81 Å. There are three inequivalent Si4+ sites. In the first Si4+ site, Si4+ is bonded to four N3- atoms to form SiN4 tetrahedra that share corners with four equivalent LaN6 octahedra, corners with two equivalent LaN7 pentagonal bipyramids, and a cornercorner with one SiN4 tetrahedra. The corner-sharing octahedra tilt angles range from 12–72°. There is two shorter (1.76 Å) and two longer (1.78 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 SiN4 tetrahedra and edges with two equivalent LaN7 pentagonal bipyramids. There is three shorter (1.72 Å) and one longer (1.73 Å) Si–N bond length. In the third Si4+ site, Si4+ is bonded to four N3- atoms to form SiN4 tetrahedra that share corners with two equivalent LaN6 octahedra, corners with two equivalent SiN4 tetrahedra, and edges with two equivalent LaN7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 38°. There is two shorter (1.74 Å) and two longer (1.75 Å) Si–N bond length. There are six inequivalent N3- sites. In the first N3- site, N3- is bonded in a distorted linear geometry to three La3+ and two Si4+ atoms. In the second N3- site, N3- is bonded in a 2-coordinate geometry to three La3+ and two Si4+ atoms. In the third N3- site, N3- is bonded in a distorted trigonal bipyramidal geometry to four La3+ and one Si4+ atom. In the fourth N3- site, N3- is bonded in a 1-coordinate geometry to four La3+ and one Si4+ atom. In the fifth N3- site, N3- is bonded in a 6-coordinate geometry to five La3+ and one Si4+ atom. In the sixth N3- site, N3- is bonded in a 1-coordinate geometry to five La3+ and one Si4+ atom.