Materials Data on La17Al4(Si3N11)3 by Materials Project

Abstract

La17Al4(Si3N11)3 crystallizes in the cubic F-43m space group. The structure is three-dimensional. there are four inequivalent La3+ sites. In the first La3+ site, La3+ is bonded to twelve equivalent N3- atoms to form LaN12 cuboctahedra that share corners with twelve equivalent LaN6 pentagonal pyramids, faces with four equivalent LaN6 octahedra, and faces with four equivalent SiN4 tetrahedra. All La–N bond lengths are 3.03 Å. In the second La3+ site, La3+ is bonded to six N3- atoms to form distorted LaN6 pentagonal pyramids that share corners with two equivalent LaN12 cuboctahedra, corners with two equivalent LaN6 octahedra, corners with four equivalent LaN6 pentagonal pyramids, corners with two equivalent AlN4 tetrahedra, corners with two equivalent SiN4 tetrahedra, and edges with three SiN4 tetrahedra. The corner-sharing octahedral tilt angles are 89°. There are a spread of La–N bond distances ranging from 2.49–2.62 Å. In the third La3+ site, La3+ is bonded in a body-centered cubic geometry to eight N3- atoms. There are four shorter (2.67 Å) and four longer (2.83 Å) La–N bond lengths. In the fourth La3+ site, La3+ is bonded to six N3- atoms to form distorted LaN6 octahedra that share corners with three equivalent LaN6 pentagonal pyramids, corners with six SiN4 tetrahedra, edges with three equivalent LaN6 octahedra, and a faceface with one LaN12 cuboctahedra. There are three shorter (2.46 Å) and three longer (2.70 Å) La–N bond lengths. Al3+ is bonded to four N3- atoms to form AlN4 tetrahedra that share corners with three equivalent LaN6 pentagonal pyramids, corners with three equivalent AlN4 tetrahedra, and corners with three equivalent SiN4 tetrahedra. There is three shorter (1.89 Å) and one longer (1.90 Å) Al–N bond length. 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 three equivalent LaN6 octahedra, a cornercorner with one SiN4 tetrahedra, edges with three equivalent LaN6 pentagonal pyramids, and a faceface with one LaN12 cuboctahedra. The corner-sharing octahedral tilt angles are 4°. There is three shorter (1.74 Å) and one longer (1.82 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 LaN6 octahedra, corners with three equivalent LaN6 pentagonal pyramids, and corners with three equivalent AlN4 tetrahedra. The corner-sharing octahedral tilt angles are 64°. There is one shorter (1.73 Å) and three longer (1.78 Å) Si–N bond length. In the third Si4+ site, Si4+ is bonded to four equivalent N3- atoms to form SiN4 tetrahedra that share corners with four equivalent SiN4 tetrahedra and edges with six equivalent LaN6 pentagonal pyramids. All Si–N bond lengths are 1.75 Å. There are five inequivalent N3- sites. In the first N3- site, N3- is bonded to three La3+, one Al3+, and one Si4+ atom to form distorted NLa3AlSi trigonal bipyramids that share corners with two NLa3Si tetrahedra, corners with five NLa3AlSi trigonal bipyramids, and edges with four equivalent NLa3AlSi trigonal bipyramids. In the second N3- site, N3- is bonded to three equivalent La3+ and two Si4+ atoms to form NLa3Si2 trigonal bipyramids that share corners with six equivalent NLa3AlSi trigonal bipyramids and edges with three equivalent NLa3Si2 trigonal bipyramids. In the third N3- site, N3- is bonded to four equivalent Al3+ atoms to form corner-sharing NAl4 tetrahedra. In the fourth N3- site, N3- is bonded to three equivalent La3+ and one Si4+ atom to form distorted NLa3Si tetrahedra that share corners with three equivalent NLa3AlSi trigonal bipyramids and edges with three equivalent NLa3Si tetrahedra. In the fifth N3- site, N3- is bonded in a 1-coordinate geometry to five La3+ and one Si4+ atom.