DOI: 10.17188/1291738
title: Materials Data on Hf5N5O2 by Materials Project

description: Hf5N5O2 crystallizes in the monoclinic Cm space group. The structure is three-dimensional. there are five inequivalent Hf sites. In the first Hf site, Hf is bonded to five N and one O atom to form a mixture of edge and corner-sharing HfN5O octahedra. The corner-sharing octahedra tilt angles range from 2–59°. There are a spread of Hf–N bond distances ranging from 2.16–2.22 Å. The Hf–O bond length is 2.18 Å. In the second Hf site, Hf is bonded in a 7-coordinate geometry to five N and two equivalent O atoms. There are a spread of Hf–N bond distances ranging from 2.26–2.41 Å. Both Hf–O bond lengths are 2.22 Å. In the third Hf site, Hf is bonded in a 7-coordinate geometry to five N and two equivalent O atoms. There are a spread of Hf–N bond distances ranging from 2.25–2.38 Å. Both Hf–O bond lengths are 2.23 Å. In the fourth Hf site, Hf is bonded to five N and one O atom to form a mixture of edge and corner-sharing HfN5O octahedra. The corner-sharing octahedra tilt angles range from 2–59°. There are a spread of Hf–N bond distances ranging from 2.16–2.22 Å. The Hf–O bond length is 2.16 Å. In the fifth Hf site, Hf is bonded to four N and two O atoms to form HfN4O2 octahedra that share corners with two HfN5O octahedra and edges with two equivalent HfN4O2 octahedra. The corner-sharing octahedral tilt angles are 59°. There are two shorter (2.19 Å) and two longer (2.20 Å) Hf–N bond lengths. There are one shorter (2.11 Å) and one longer (2.12 Å) Hf–O bond lengths. There are five inequivalent N sites. In the first N site, N is bonded in a square co-planar geometry to four Hf atoms. In the second N site, N is bonded to five Hf atoms to form distorted NHf5 square pyramids that share corners with four equivalent OHf4 tetrahedra, corners with six NHf5 trigonal bipyramids, edges with two equivalent NHf5 square pyramids, edges with three OHf4 tetrahedra, and edges with four NHf5 trigonal bipyramids. In the third N site, N is bonded to five Hf atoms to form NHf5 trigonal bipyramids that share corners with two equivalent NHf5 square pyramids, corners with five OHf4 tetrahedra, corners with two equivalent NHf5 trigonal bipyramids, an edgeedge with one NHf5 square pyramid, an edgeedge with one OHf4 tetrahedra, and edges with four NHf5 trigonal bipyramids. In the fourth N site, N is bonded to five Hf atoms to form NHf5 trigonal bipyramids that share corners with two equivalent NHf5 square pyramids, corners with five OHf4 tetrahedra, corners with two equivalent NHf5 trigonal bipyramids, an edgeedge with one OHf4 tetrahedra, and edges with five NHf5 trigonal bipyramids. In the fifth N site, N is bonded to five Hf atoms to form distorted NHf5 trigonal bipyramids that share corners with two equivalent NHf5 square pyramids, corners with four equivalent OHf4 tetrahedra, corners with four NHf5 trigonal bipyramids, edges with three equivalent NHf5 square pyramids, edges with three OHf4 tetrahedra, and edges with three NHf5 trigonal bipyramids. There are two inequivalent O sites. In the first O site, O is bonded to four Hf atoms to form OHf4 tetrahedra that share corners with three OHf4 tetrahedra, corners with nine NHf5 trigonal bipyramids, edges with two equivalent NHf5 square pyramids, and edges with two NHf5 trigonal bipyramids. In the second O site, O is bonded to four Hf atoms to form OHf4 tetrahedra that share corners with four equivalent NHf5 square pyramids, corners with three OHf4 tetrahedra, corners with five NHf5 trigonal bipyramids, an edgeedge with one NHf5 square pyramid, and edges with three NHf5 trigonal bipyramids.