Materials Data on Ta4AlN3 by Materials Project
Ta4AlN3 is MAX Phase-like structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. there are two inequivalent Ta sites. In the first Ta site, Ta is bonded to six N atoms to form a mixture of distorted edge and corner-sharing TaN6 pentagonal pyramids. There are three shorter (2.21 Å) and three longer (2.23 Å) Ta–N bond lengths. In the second Ta site, Ta is bonded in a 3-coordinate geometry to three equivalent Al and three equivalent N atoms. All Ta–Al bond lengths are 2.81 Å. All Ta–N bond lengths are 2.23 Å. Al is bonded to six equivalent Ta and six equivalent Al atoms to form distorted AlTa6Al6 cuboctahedra that share corners with six equivalent AlTa6Al6 cuboctahedra, corners with six equivalent NTa6 octahedra, edges with six equivalent AlTa6Al6 cuboctahedra, edges with six equivalent NTa6 octahedra, and faces with six equivalent AlTa6Al6 cuboctahedra. The corner-sharing octahedral tilt angles are 13°. All Al–Al bond lengths are 2.98 Å. There are two inequivalent N sites. In the first N site, N is bonded to six equivalent Ta atoms to form a mixture of edge, face, and corner-sharing NTa6 octahedra. The corner-sharing octahedral tilt angles are 46°. In the second N site, N is bonded to six Ta atoms to form NTa6 octahedra that share corners with three equivalent AlTa6Al6 cuboctahedra, corners with six equivalent NTa6 octahedra, edges with three equivalent AlTa6Al6 cuboctahedra, edges with six equivalent NTa6 octahedra, and a faceface with one NTa6 octahedra. The corner-sharing octahedral tilt angles are 46°.