Materials Data on Hf4N3 by Materials Project
Hf4N3 is MAX Phase-derived structured and crystallizes in the trigonal R3m space group. The structure is two-dimensional and consists of three Hf4N3 sheets oriented in the (0, 0, 1) direction. there are four inequivalent Hf sites. In the first Hf site, Hf is bonded to six N atoms to form a mixture of distorted corner and edge-sharing HfN6 pentagonal pyramids. The corner-sharing octahedral tilt angles are 2°. There are three shorter (2.29 Å) and three longer (2.32 Å) Hf–N bond lengths. In the second Hf site, Hf is bonded in a distorted T-shaped geometry to three equivalent N atoms. All Hf–N bond lengths are 2.23 Å. In the third Hf site, Hf is bonded in a distorted T-shaped geometry to three equivalent N atoms. All Hf–N bond lengths are 2.29 Å. In the fourth Hf site, Hf is bonded to six N atoms to form a mixture of corner and edge-sharing HfN6 octahedra. There are three shorter (2.22 Å) and three longer (2.27 Å) Hf–N bond lengths. There are three inequivalent N sites. In the first N site, N is bonded to six Hf atoms to form a mixture of corner and edge-sharing NHf6 octahedra. The corner-sharing octahedral tilt angles are 2°. In the second N site, N is bonded to six Hf atoms to form a mixture of corner, edge, and face-sharing NHf6 octahedra. The corner-sharing octahedral tilt angles are 47°. In the third N site, N is bonded to six Hf atoms to form a mixture of corner, edge, and face-sharing NHf6 octahedra. The corner-sharing octahedra tilt angles range from 2–47°.