DOI: 10.17188/1291559
title: Materials Data on Hf2N2O by Materials Project

description: Hf2ON2 crystallizes in the monoclinic Cm space group. The structure is three-dimensional. there are six inequivalent Hf4+ sites. In the first Hf4+ site, Hf4+ is bonded to four N3- and two equivalent O2- atoms to form distorted HfN4O2 octahedra that share corners with two equivalent HfN2O4 octahedra and edges with three HfN4O2 octahedra. The corner-sharing octahedral tilt angles are 5°. There are a spread of Hf–N bond distances ranging from 2.06–2.13 Å. Both Hf–O bond lengths are 2.49 Å. In the second Hf4+ site, Hf4+ is bonded in a 7-coordinate geometry to four N3- and three O2- atoms. There are a spread of Hf–N bond distances ranging from 2.17–2.40 Å. There are two shorter (2.18 Å) and one longer (2.43 Å) Hf–O bond lengths. In the third Hf4+ site, Hf4+ is bonded in a 7-coordinate geometry to six N3- and one O2- atom. There are a spread of Hf–N bond distances ranging from 2.09–2.41 Å. The Hf–O bond length is 2.71 Å. In the fourth Hf4+ site, Hf4+ is bonded in a 7-coordinate geometry to five N3- and two O2- atoms. There are a spread of Hf–N bond distances ranging from 2.13–2.30 Å. There are one shorter (2.19 Å) and one longer (2.67 Å) Hf–O bond lengths. In the fifth Hf4+ site, Hf4+ is bonded in a 7-coordinate geometry to five N3- and two O2- atoms. There are a spread of Hf–N bond distances ranging from 2.12–2.39 Å. There are one shorter (2.20 Å) and one longer (2.33 Å) Hf–O bond lengths. In the sixth Hf4+ site, Hf4+ is bonded to two N3- and four O2- atoms to form a mixture of corner and edge-sharing HfN2O4 octahedra. The corner-sharing octahedral tilt angles are 5°. There are one shorter (2.06 Å) and one longer (2.16 Å) Hf–N bond lengths. There are two shorter (2.05 Å) and two longer (2.27 Å) Hf–O bond lengths. There are six inequivalent N3- sites. In the first N3- site, N3- is bonded in a 4-coordinate geometry to four Hf4+ atoms. In the second N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 tetrahedra that share corners with two equivalent NHf4 tetrahedra, a cornercorner with one OHf4 trigonal pyramid, corners with two equivalent NHf4 trigonal pyramids, and edges with two equivalent NHf4 tetrahedra. In the third N3- site, N3- is bonded in a 5-coordinate geometry to five Hf4+ atoms. In the fourth N3- site, N3- is bonded to four Hf4+ atoms to form distorted NHf4 trigonal pyramids that share corners with three NHf4 tetrahedra, corners with two equivalent NHf4 trigonal pyramids, and edges with two equivalent OHf4 trigonal pyramids. In the fifth N3- site, N3- is bonded in a 5-coordinate geometry to five Hf4+ atoms. In the sixth N3- site, N3- is bonded to four Hf4+ atoms to form NHf4 tetrahedra that share corners with two equivalent NHf4 tetrahedra, a cornercorner with one NHf4 trigonal pyramid, corners with two equivalent OHf4 trigonal pyramids, and edges with two equivalent NHf4 tetrahedra. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded to four Hf4+ atoms to form distorted OHf4 trigonal pyramids that share corners with three NHf4 tetrahedra, corners with two equivalent OHf4 trigonal pyramids, and edges with two equivalent NHf4 trigonal pyramids. In the second O2- site, O2- is bonded in a 4-coordinate geometry to four Hf4+ atoms. In the third O2- site, O2- is bonded in a 6-coordinate geometry to six Hf4+ atoms.