Materials Data on Nb4AlN3 by Materials Project

Abstract

Nb4AlN3 is MAX Phase-like structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. there are two inequivalent Nb sites. In the first Nb site, Nb is bonded to six N atoms to form a mixture of distorted corner and edge-sharing NbN6 pentagonal pyramids. There are three shorter (2.21 Å) and three longer (2.24 Å) Nb–N bond lengths. In the second Nb site, Nb is bonded in a 3-coordinate geometry to three equivalent Al and three equivalent N atoms. All Nb–Al bond lengths are 2.83 Å. All Nb–N bond lengths are 2.23 Å. Al is bonded to six equivalent Nb and six equivalent Al atoms to form AlNb6Al6 cuboctahedra that share corners with six equivalent AlNb6Al6 cuboctahedra, corners with six equivalent NNb6 octahedra, edges with six equivalent AlNb6Al6 cuboctahedra, edges with six equivalent NNb6 octahedra, and faces with six equivalent AlNb6Al6 cuboctahedra. The corner-sharing octahedral tilt angles are 13°. All Al–Al bond lengths are 3.01 Å. There are two inequivalent N sites. In the first N site, N is bonded to six equivalent Nb atoms to form a mixture of corner, edge, and face-sharing NNb6 octahedra. The corner-sharing octahedral tilt angles are 46°. In the second N site, N is bonded to six Nb atoms to form NNb6 octahedra that share corners with three equivalent AlNb6Al6 cuboctahedra, corners with six equivalent NNb6 octahedra, edges with three equivalent AlNb6Al6 cuboctahedra, edges with six equivalent NNb6 octahedra, and a faceface with one NNb6 octahedra. The corner-sharing octahedral tilt angles are 46°.