DOE OSTI2020
Ta3Mo3N4 crystallizes in the tetragonal P4mm space group. The structure is three-dimensional. there are three inequivalent Ta sites. In the first Ta site, Ta is bonded to five N atoms to form a mixture of distorted edge and corner-sharing TaN5 square pyramids. There are four shorter (2.19 Å) and one longer (2.27 Å) Ta–N bond lengths. In the second Ta site, Ta is bonded to five N atoms to form distorted TaN5 square pyramids that share corners with four equivalent TaN5 square pyramids, edges with four equivalent TaN5 square pyramids, and edges with four equivalent MoN5 square pyramids. There are four shorter (2.19 Å) and one longer (2.26 Å) Ta–N bond lengths. In the third Ta site, Ta is bonded to five N atoms to form a mixture of distorted edge and corner-sharing TaN5 square pyramids. There are four shorter (2.18 Å) and one longer (2.23 Å) Ta–N bond lengths. There are three inequivalent Mo sites. In the first Mo site, Mo is bonded in a linear geometry to two N atoms. There are one shorter (2.16 Å) and one longer (2.26 Å) Mo–N bond lengths. In the second Mo site, Mo is bonded in a distorted linear geometry to two N atoms. Both Mo–N bond lengths are 2.24 Å. In the third Mo site, Mo is bonded to five N atoms to form MoN5 square pyramids that share corners with four equivalent MoN5 square pyramids, edges with four equivalent TaN5 square pyramids, and edges with four equivalent MoN5 square pyramids. There are four shorter (2.18 Å) and one longer (2.23 Å) Mo–N bond lengths. There are four inequivalent N sites. In the first N site, N is bonded to four equivalent Ta and two Mo atoms to form distorted NTa4Mo2 octahedra that share corners with five NTa5Mo octahedra and edges with eight NTaMo5 octahedra. The corner-sharing octahedra tilt angles range from 0–20°. In the second N site, N is bonded to five Ta and one Mo atom to form NTa5Mo octahedra that share corners with five NTaMo5 octahedra and edges with eight NTa5Mo octahedra. The corner-sharing octahedra tilt angles range from 0–18°. In the third N site, N is bonded to one Ta and five Mo atoms to form a mixture of edge and corner-sharing NTaMo5 octahedra. The corner-sharing octahedra tilt angles range from 0–18°. In the fourth N site, N is bonded to five Ta and one Mo atom to form a mixture of distorted edge and corner-sharing NTa5Mo octahedra. The corner-sharing octahedra tilt angles range from 0–20°.