Materials Data on TaCo4Si by Materials Project

Abstract

TaCo4Si is Frank-Kasper $\mu$ Phase-derived structured and crystallizes in the trigonal P-3m1 space group. The structure is three-dimensional. Ta is bonded in a 7-coordinate geometry to twelve Co and one Si atom. There are a spread of Ta–Co bond distances ranging from 2.68–2.90 Å. The Ta–Si bond length is 2.67 Å. There are three inequivalent Co sites. In the first Co site, Co is bonded to six equivalent Ta and six equivalent Co atoms to form CoTa6Co6 cuboctahedra that share corners with twelve equivalent CoTa3Co6Si3 cuboctahedra, edges with six equivalent CoTa6Co6 cuboctahedra, and faces with twenty CoCo6Si6 cuboctahedra. All Co–Co bond lengths are 2.36 Å. In the second Co site, Co is bonded to six equivalent Co and six equivalent Si atoms to form CoCo6Si6 cuboctahedra that share corners with twelve equivalent CoTa3Co6Si3 cuboctahedra, edges with six equivalent CoCo6Si6 cuboctahedra, and faces with twenty CoTa6Co6 cuboctahedra. All Co–Co bond lengths are 2.28 Å. All Co–Si bond lengths are 2.76 Å. In the third Co site, Co is bonded to three equivalent Ta, six Co, and three equivalent Si atoms to form distorted CoTa3Co6Si3 cuboctahedra that share corners with eighteen CoTa6Co6 cuboctahedra, edges with six equivalent CoTa3Co6Si3 cuboctahedra, and faces with eighteen CoTa6Co6 cuboctahedra. There are two shorter (2.33 Å) and two longer (2.42 Å) Co–Co bond lengths. There are one shorter (2.55 Å) and two longer (2.78 Å) Co–Si bond lengths. Si is bonded in a 1-coordinate geometry to one Ta, twelve Co, and three equivalent Si atoms. All Si–Si bond lengths are 2.84 Å.