Hf3N4 crystallizes in the orthorhombic Pnma space group. There are three inequivalent Hf sites. In the first Hf site, Hf(1) is bonded to one N(4), two equivalent N(1), and three equivalent N(3) atoms to form a mixture of edge and corner-sharing HfN6 octahedra. The corner-sharing octahedral tilt angles range from 5-69°. In the second Hf site, Hf(2) is bonded in a 7-coordinate geometry to one N(1), one N(3), two equivalent N(4), and three equivalent N(2) atoms. In the third Hf site, Hf(3) is bonded to one N(1), one N(2), two equivalent N(3), and two equivalent N(4) atoms to form a mixture of distorted edge and corner-sharing HfN6 octahedra. The corner-sharing octahedral tilt angles range from 5-69°. There are four inequivalent N sites. In the first N site, N(1) is bonded to one Hf(2), one Hf(3), and two equivalent Hf(1) atoms to form distorted NHf4 trigonal pyramids that share corners with three equivalent N(3)Hf6 octahedra, corners with four equivalent N(2)Hf4 tetrahedra, corners with two equivalent N(1)Hf4 trigonal pyramids, and edges with three equivalent N(3)Hf6 octahedra. The corner-sharing octahedral tilt angles range from 10-38°. In the second N site, N(2) is bonded to one Hf(3) and three equivalent Hf(2) atoms to form NHf4 tetrahedra that share  a cornercorner with one N(3)Hf6 octahedra, corners with two equivalent N(2)Hf4 tetrahedra, corners with four equivalent N(1)Hf4 trigonal pyramids, edges with two equivalent N(3)Hf6 octahedra, and edges with two equivalent N(2)Hf4 tetrahedra. The corner-sharing octahedral tilt angles are 44°. In the third N site, N(3) is bonded to one Hf(2), two equivalent Hf(3), and three equivalent Hf(1) atoms to form distorted NHf6 octahedra that share  a cornercorner with one N(2)Hf4 tetrahedra, corners with three equivalent N(1)Hf4 trigonal pyramids, edges with four equivalent N(3)Hf6 octahedra, edges with two equivalent N(2)Hf4 tetrahedra, and edges with three equivalent N(1)Hf4 trigonal pyramids. In the fourth N site, N(4) is bonded in a 5-coordinate geometry to one Hf(1), two equivalent Hf(2), and two equivalent Hf(3) atoms.
Hf3N4 crystallizes in the orthorhombic Pnma space group. There are three inequivalent Hf sites. In the first Hf site, Hf(1) is bonded to one N(4), two equivalent N(1), and three equivalent N(3) atoms to form a mixture of edge and corner-sharing HfN6 octahedra. The corner-sharing octahedral tilt angles range from 5-69°. The Hf(1)-N(4) bond length is 2.11 Å. Both Hf(1)-N(1) bond lengths are 2.08 Å. There are two shorter (2.32 Å) and one longer (2.35 Å) Hf(1)-N(3) bond length. In the second Hf site, Hf(2) is bonded in a 7-coordinate geometry to one N(1), one N(3), two equivalent N(4), and three equivalent N(2) atoms. The Hf(2)-N(1) bond length is 2.16 Å. The Hf(2)-N(3) bond length is 2.74 Å. Both Hf(2)-N(4) bond lengths are 2.44 Å. There are two shorter (2.08 Å) and one longer (2.15 Å) Hf(2)-N(2) bond length. In the third Hf site, Hf(3) is bonded to one N(1), one N(2), two equivalent N(3), and two equivalent N(4) atoms to form a mixture of distorted edge and corner-sharing HfN6 octahedra. The corner-sharing octahedral tilt angles range from 5-69°. The Hf(3)-N(1) bond length is 2.29 Å. The Hf(3)-N(2) bond length is 2.07 Å. Both Hf(3)-N(3) bond lengths are 2.28 Å. Both Hf(3)-N(4) bond lengths are 2.19 Å. There are four inequivalent N sites. In the first N site, N(1) is bonded to one Hf(2), one Hf(3), and two equivalent Hf(1) atoms to form distorted NHf4 trigonal pyramids that share corners with three equivalent N(3)Hf6 octahedra, corners with four equivalent N(2)Hf4 tetrahedra, corners with two equivalent N(1)Hf4 trigonal pyramids, and edges with three equivalent N(3)Hf6 octahedra. The corner-sharing octahedral tilt angles range from 10-38°. In the second N site, N(2) is bonded to one Hf(3) and three equivalent Hf(2) atoms to form NHf4 tetrahedra that share  a cornercorner with one N(3)Hf6 octahedra, corners with two equivalent N(2)Hf4 tetrahedra, corners with four equivalent N(1)Hf4 trigonal pyramids, edges with two equivalent N(3)Hf6 octahedra, and edges with two equivalent N(2)Hf4 tetrahedra. The corner-sharing octahedral tilt angles are 44°. In the third N site, N(3) is bonded to one Hf(2), two equivalent Hf(3), and three equivalent Hf(1) atoms to form distorted NHf6 octahedra that share  a cornercorner with one N(2)Hf4 tetrahedra, corners with three equivalent N(1)Hf4 trigonal pyramids, edges with four equivalent N(3)Hf6 octahedra, edges with two equivalent N(2)Hf4 tetrahedra, and edges with three equivalent N(1)Hf4 trigonal pyramids. In the fourth N site, N(4) is bonded in a 5-coordinate geometry to one Hf(1), two equivalent Hf(2), and two equivalent Hf(3) atoms.