DOI: 10.17188/1204272
title: Materials Data on Ca3(AlN2)2 by Materials Project

description: Ca3(AlN2)2 crystallizes in the orthorhombic P2_12_12_1 space group. The structure is three-dimensional. there are six inequivalent Ca2+ sites. In the first Ca2+ site, Ca2+ is bonded in a 7-coordinate geometry to seven N3- atoms. There are a spread of Ca–N bond distances ranging from 2.42–3.02 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 2.32–2.65 Å. In the third Ca2+ site, Ca2+ is bonded in a 3-coordinate geometry to three N3- atoms. There are a spread of Ca–N bond distances ranging from 2.43–2.48 Å. In the fourth Ca2+ site, Ca2+ is bonded in a distorted rectangular see-saw-like geometry to four N3- atoms. There are a spread of Ca–N bond distances ranging from 2.43–2.52 Å. In the fifth Ca2+ site, Ca2+ is bonded in a 6-coordinate geometry to six N3- atoms. There are a spread of Ca–N bond distances ranging from 2.40–3.01 Å. In the sixth Ca2+ site, Ca2+ is bonded to five N3- atoms to form distorted CaN5 square pyramids that share corners with three AlN4 tetrahedra and edges with three AlN4 tetrahedra. There are a spread of Ca–N bond distances ranging from 2.39–2.62 Å. There are four inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to four N3- atoms to form AlN4 tetrahedra that share corners with two equivalent CaN5 square pyramids, corners with four AlN4 tetrahedra, and an edgeedge with one AlN4 tetrahedra. There are a spread of Al–N bond distances ranging from 1.84–1.97 Å. In the second Al3+ site, Al3+ is bonded to four N3- atoms to form AlN4 tetrahedra that share corners with four AlN4 tetrahedra, an edgeedge with one CaN5 square pyramid, and an edgeedge with one AlN4 tetrahedra. There are a spread of Al–N bond distances ranging from 1.84–1.97 Å. In the third Al3+ site, Al3+ is bonded to four N3- atoms to form AlN4 tetrahedra that share corners with four AlN4 tetrahedra and an edgeedge with one CaN5 square pyramid. There are a spread of Al–N bond distances ranging from 1.89–1.95 Å. In the fourth Al3+ site, Al3+ is bonded to four N3- atoms to form AlN4 tetrahedra that share a cornercorner with one CaN5 square pyramid, corners with four AlN4 tetrahedra, and an edgeedge with one CaN5 square pyramid. There are a spread of Al–N bond distances ranging from 1.86–1.95 Å. There are eight inequivalent N3- sites. In the first N3- site, N3- is bonded to four Ca2+ and two Al3+ atoms to form distorted NCa4Al2 octahedra that share corners with four NCa4Al2 octahedra and edges with two NCa5Al octahedra. The corner-sharing octahedra tilt angles range from 9–68°. In the second N3- site, N3- is bonded in a 3-coordinate geometry to three Ca2+ and three Al3+ atoms. In the third N3- site, N3- is bonded to five Ca2+ and one Al3+ atom to form a mixture of corner and edge-sharing NCa5Al octahedra. The corner-sharing octahedra tilt angles range from 11–52°. In the fourth N3- site, N3- is bonded in a 2-coordinate geometry to three Ca2+ and two Al3+ atoms. In the fifth N3- site, N3- is bonded to five Ca2+ and one Al3+ atom to form a mixture of distorted corner and edge-sharing NCa5Al octahedra. The corner-sharing octahedra tilt angles range from 9–65°. In the sixth N3- site, N3- is bonded to four Ca2+ and two Al3+ atoms to form distorted NCa4Al2 octahedra that share corners with six NCa4Al2 octahedra and edges with two NCa5Al octahedra. The corner-sharing octahedra tilt angles range from 11–68°. In the seventh N3- site, N3- is bonded in a 4-coordinate geometry to three Ca2+ and two Al3+ atoms. In the eighth N3- site, N3- is bonded in a 3-coordinate geometry to three Ca2+ and three Al3+ atoms.