Materials Data on LiCaAl3N4 by Materials Project
LiCaAl3N4 crystallizes in the tetragonal I4_1/a space group. The structure is three-dimensional. Li1+ is bonded to four N3- atoms to form LiN4 trigonal pyramids that share corners with four AlN4 tetrahedra, corners with four equivalent AlN4 trigonal pyramids, and edges with two AlN4 tetrahedra. There are a spread of Li–N bond distances ranging from 1.99–2.29 Å. Ca2+ is bonded in a distorted body-centered cubic geometry to eight N3- atoms. There are a spread of Ca–N bond distances ranging from 2.54–2.94 Å. There are three inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to four N3- atoms to form AlN4 tetrahedra that share corners with four equivalent AlN4 tetrahedra, corners with two equivalent LiN4 trigonal pyramids, corners with two equivalent AlN4 trigonal pyramids, an edgeedge with one LiN4 trigonal pyramid, and an edgeedge with one AlN4 trigonal pyramid. There are a spread of Al–N bond distances ranging from 1.87–1.95 Å. In the second Al3+ site, Al3+ is bonded to four N3- atoms to form AlN4 trigonal pyramids that share corners with two equivalent AlN4 tetrahedra, corners with two equivalent AlN4 trigonal pyramids, corners with four equivalent LiN4 trigonal pyramids, an edgeedge with one AlN4 tetrahedra, and an edgeedge with one AlN4 trigonal pyramid. There are a spread of Al–N bond distances ranging from 1.85–1.96 Å. In the third Al3+ site, Al3+ is bonded to four N3- atoms to form AlN4 tetrahedra that share corners with six AlN4 tetrahedra, corners with two equivalent LiN4 trigonal pyramids, an edgeedge with one AlN4 tetrahedra, and an edgeedge with one LiN4 trigonal pyramid. There are a spread of Al–N bond distances ranging from 1.88–1.94 Å. There are four inequivalent N3- sites. In the first N3- site, N3- is bonded in a 6-coordinate geometry to one Li1+, two equivalent Ca2+, and three Al3+ atoms. In the second N3- site, N3- is bonded in a 4-coordinate geometry to one Li1+, two equivalent Ca2+, and three Al3+ atoms. In the third N3- site, N3- is bonded in a 4-coordinate geometry to one Li1+, two equivalent Ca2+, and three Al3+ atoms. In the fourth N3- site, N3- is bonded in a 3-coordinate geometry to one Li1+, two equivalent Ca2+, and three Al3+ atoms.