Materials Data on HfTa3C4 by Materials Project
HfTa3C4 is Caswellsilverite-like structured and crystallizes in the trigonal P-3m1 space group. The structure is three-dimensional. Hf4+ is bonded to six equivalent C4- atoms to form HfC6 octahedra that share corners with twelve equivalent TaC6 octahedra, edges with six equivalent HfC6 octahedra, and faces with two equivalent TaC6 octahedra. The corner-sharing octahedral tilt angles are 47°. All Hf–C bond lengths are 2.36 Å. There are two inequivalent Ta4+ sites. In the first Ta4+ site, Ta4+ is bonded to six equivalent C4- atoms to form a mixture of corner, edge, and face-sharing TaC6 octahedra. The corner-sharing octahedral tilt angles are 47°. All Ta–C bond lengths are 2.28 Å. In the second Ta4+ site, Ta4+ is bonded to six C4- atoms to form TaC6 octahedra that share corners with six equivalent HfC6 octahedra, corners with six equivalent TaC6 octahedra, edges with six equivalent TaC6 octahedra, a faceface with one HfC6 octahedra, and a faceface with one TaC6 octahedra. The corner-sharing octahedral tilt angles are 47°. There are three shorter (2.27 Å) and three longer (2.31 Å) Ta–C bond lengths. There are two inequivalent C4- sites. In the first C4- site, C4- is bonded to three equivalent Hf4+ and three equivalent Ta4+ atoms to form a mixture of distorted corner and edge-sharing CHf3Ta3 pentagonal pyramids. In the second C4- site, C4- is bonded to six Ta4+ atoms to form a mixture of distorted corner and edge-sharing CTa6 pentagonal pyramids.