Materials Data on CaLa3Si8 by Materials Project
CaLa3Si8 is hexagonal omega structure-derived structured and crystallizes in the tetragonal P-4m2 space group. The structure is three-dimensional. Ca2+ is bonded to twelve Si1- atoms to form CaSi12 cuboctahedra that share edges with four equivalent CaSi12 cuboctahedra, edges with eight LaSi12 cuboctahedra, faces with four equivalent CaSi12 cuboctahedra, and faces with four LaSi12 cuboctahedra. There are four shorter (3.16 Å) and eight longer (3.24 Å) Ca–Si bond lengths. There are three inequivalent La2+ sites. In the first La2+ site, La2+ is bonded to twelve Si1- atoms to form a mixture of edge and face-sharing LaSi12 cuboctahedra. There are four shorter (3.18 Å) and eight longer (3.24 Å) La–Si bond lengths. In the second La2+ site, La2+ is bonded to twelve Si1- atoms to form LaSi12 cuboctahedra that share edges with four equivalent CaSi12 cuboctahedra, edges with eight LaSi12 cuboctahedra, faces with two equivalent CaSi12 cuboctahedra, and faces with six LaSi12 cuboctahedra. There are a spread of La–Si bond distances ranging from 3.17–3.24 Å. In the third La2+ site, La2+ is bonded to twelve Si1- atoms to form LaSi12 cuboctahedra that share edges with four equivalent CaSi12 cuboctahedra, edges with eight LaSi12 cuboctahedra, faces with two equivalent CaSi12 cuboctahedra, and faces with six LaSi12 cuboctahedra. There are a spread of La–Si bond distances ranging from 3.17–3.24 Å. There are six inequivalent Si1- sites. In the first Si1- site, Si1- is bonded in a 9-coordinate geometry to four equivalent Ca2+, two equivalent La2+, and three Si1- atoms. There are one shorter (2.36 Å) and two longer (2.42 Å) Si–Si bond lengths. In the second Si1- site, Si1- is bonded in a 9-coordinate geometry to six La2+ and three Si1- atoms. There are one shorter (2.39 Å) and two longer (2.43 Å) Si–Si bond lengths. In the third Si1- site, Si1- is bonded in a 9-coordinate geometry to two equivalent Ca2+, four equivalent La2+, and three Si1- atoms. The Si–Si bond length is 2.39 Å. In the fourth Si1- site, Si1- is bonded in a 9-coordinate geometry to six La2+ and three Si1- atoms. The Si–Si bond length is 2.39 Å. In the fifth Si1- site, Si1- is bonded in a 9-coordinate geometry to four equivalent Ca2+, two equivalent La2+, and three Si1- atoms. Both Si–Si bond lengths are 2.42 Å. In the sixth Si1- site, Si1- is bonded in a 9-coordinate geometry to six La2+ and three Si1- atoms. Both Si–Si bond lengths are 2.43 Å.