Materials Data on HfNb4CN4 by Materials Project

Abstract

HfNb4CN4 is alpha Po-derived structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Hf4+ is bonded to four equivalent C4- and two equivalent N3- atoms to form HfC4N2 octahedra that share corners with two equivalent NbN6 octahedra, corners with four equivalent HfC4N2 octahedra, edges with four equivalent HfC4N2 octahedra, and edges with eight equivalent NbCN5 octahedra. The corner-sharing octahedral tilt angles are 0°. All Hf–C bond lengths are 2.25 Å. Both Hf–N bond lengths are 2.24 Å. There are two inequivalent Nb3+ sites. In the first Nb3+ site, Nb3+ is bonded to one C4- and five N3- atoms to form NbCN5 octahedra that share corners with six NbCN5 octahedra, edges with four equivalent HfC4N2 octahedra, and edges with eight NbCN5 octahedra. The corner-sharing octahedra tilt angles range from 0–1°. The Nb–C bond length is 2.22 Å. All Nb–N bond lengths are 2.25 Å. In the second Nb3+ site, Nb3+ is bonded to six N3- atoms to form NbN6 octahedra that share a cornercorner with one HfC4N2 octahedra, corners with five NbCN5 octahedra, and edges with twelve NbCN5 octahedra. The corner-sharing octahedral tilt angles are 0°. There are a spread of Nb–N bond distances ranging from 2.21–2.25 Å. C4- is bonded to four equivalent Hf4+ and two equivalent Nb3+ atoms to form CHf4Nb2 octahedra that share corners with two equivalent NNb6 octahedra, corners with four equivalent CHf4Nb2 octahedra, edges with four equivalent CHf4Nb2 octahedra, and edges with eight equivalent NHfNb5 octahedra. The corner-sharing octahedral tilt angles are 0°. There are two inequivalent N3- sites. In the first N3- site, N3- is bonded to one Hf4+ and five Nb3+ atoms to form NHfNb5 octahedra that share corners with six NHfNb5 octahedra, edges with four equivalent CHf4Nb2 octahedra, and edges with eight NHfNb5 octahedra. The corner-sharing octahedra tilt angles range from 0–1°. In the second N3- site, N3- is bonded to six Nb3+ atoms to form NNb6 octahedra that share a cornercorner with one CHf4Nb2 octahedra, corners with five NHfNb5 octahedra, and edges with twelve NHfNb5 octahedra. The corner-sharing octahedral tilt angles are 0°.