Materials Data on Ca4SiN4 by Materials Project
Ca4SiN4 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are four inequivalent Ca2+ sites. In the first Ca2+ site, Ca2+ is bonded in a 5-coordinate geometry to five N3- atoms. There are a spread of Ca–N bond distances ranging from 2.39–2.81 Å. In the second Ca2+ site, Ca2+ is bonded in a 5-coordinate geometry to five N3- atoms. There are a spread of Ca–N bond distances ranging from 2.36–2.59 Å. In the third Ca2+ site, Ca2+ is bonded to five N3- atoms to form distorted CaN5 square pyramids that share corners with two equivalent CaN5 square pyramids, a cornercorner with one SiN4 tetrahedra, corners with three equivalent CaN5 trigonal bipyramids, edges with two equivalent SiN4 tetrahedra, and edges with two equivalent CaN5 trigonal bipyramids. There are a spread of Ca–N bond distances ranging from 2.43–2.76 Å. In the fourth Ca2+ site, Ca2+ is bonded to five N3- atoms to form CaN5 trigonal bipyramids that share corners with three equivalent CaN5 square pyramids, a cornercorner with one SiN4 tetrahedra, edges with two equivalent CaN5 square pyramids, edges with two equivalent SiN4 tetrahedra, and edges with two equivalent CaN5 trigonal bipyramids. There are a spread of Ca–N bond distances ranging from 2.41–2.49 Å. Si4+ is bonded to four N3- atoms to form SiN4 tetrahedra that share a cornercorner with one CaN5 square pyramid, a cornercorner with one CaN5 trigonal bipyramid, edges with two equivalent CaN5 square pyramids, and edges with two equivalent CaN5 trigonal bipyramids. There are a spread of Si–N bond distances ranging from 1.78–1.84 Å. There are four inequivalent N3- sites. In the first N3- site, N3- is bonded to five Ca2+ and one Si4+ atom to form a mixture of distorted edge, face, and corner-sharing NCa5Si octahedra. The corner-sharing octahedra tilt angles range from 16–65°. In the second N3- site, N3- is bonded to five Ca2+ and one Si4+ atom to form a mixture of distorted edge, face, and corner-sharing NCa5Si octahedra. The corner-sharing octahedra tilt angles range from 16–57°. In the third N3- site, N3- is bonded in a 1-coordinate geometry to five Ca2+ and one Si4+ atom. In the fourth N3- site, N3- is bonded in a 6-coordinate geometry to five Ca2+ and one Si4+ atom.