Materials Data on TaCo by Materials Project

Abstract

CoTa is Frank-Kasper $\mu$ Phase-like structured and crystallizes in the trigonal R-3m space group. The structure is three-dimensional. there are seven inequivalent Ta sites. In the first Ta site, Ta is bonded in a 10-coordinate geometry to seven Ta and nine equivalent Co atoms. There are a spread of Ta–Ta bond distances ranging from 2.74–2.92 Å. There are three shorter (2.81 Å) and six longer (3.03 Å) Ta–Co bond lengths. In the second Ta site, Ta is bonded in a 6-coordinate geometry to four Ta and twelve Co atoms. There are one shorter (2.77 Å) and three longer (2.88 Å) Ta–Ta bond lengths. There are a spread of Ta–Co bond distances ranging from 2.63–3.03 Å. In the third Ta site, Ta is bonded in a 8-coordinate geometry to two Ta and six equivalent Co atoms. The Ta–Ta bond length is 2.67 Å. All Ta–Co bond lengths are 2.65 Å. In the fourth Ta site, Ta is bonded in a 8-coordinate geometry to two Ta and six equivalent Co atoms. All Ta–Co bond lengths are 2.66 Å. In the fifth Ta site, Ta is bonded in a 6-coordinate geometry to six Co atoms. There are three shorter (2.68 Å) and three longer (2.79 Å) Ta–Co bond lengths. In the sixth Ta site, Ta is bonded in a 6-coordinate geometry to six Co atoms. There are three shorter (2.68 Å) and three longer (2.74 Å) Ta–Co bond lengths. In the seventh Ta site, Ta is bonded to six equivalent Ta and six equivalent Co atoms to form distorted TaTa6Co6 cuboctahedra that share corners with twelve equivalent CoTa8Co4 cuboctahedra, edges with six equivalent TaTa6Co6 cuboctahedra, and faces with eighteen equivalent CoTa8Co4 cuboctahedra. All Ta–Co bond lengths are 2.55 Å. There are three inequivalent Co sites. In the first Co site, Co is bonded to seven Ta and five Co atoms to form distorted CoTa7Co5 cuboctahedra that share corners with fifteen CoTa7Co5 cuboctahedra, edges with five CoTa7Co5 cuboctahedra, and faces with thirteen CoTa6Co6 cuboctahedra. There are three shorter (2.43 Å) and two longer (2.49 Å) Co–Co bond lengths. In the second Co site, Co is bonded to eight Ta and four equivalent Co atoms to form distorted CoTa8Co4 cuboctahedra that share corners with two equivalent TaTa6Co6 cuboctahedra, corners with thirteen CoTa7Co5 cuboctahedra, edges with five CoTa7Co5 cuboctahedra, faces with three equivalent TaTa6Co6 cuboctahedra, and faces with ten equivalent CoTa8Co4 cuboctahedra. There are two shorter (2.40 Å) and two longer (2.52 Å) Co–Co bond lengths. In the third Co site, Co is bonded to six equivalent Ta and six equivalent Co atoms to form CoTa6Co6 cuboctahedra that share corners with twelve equivalent CoTa7Co5 cuboctahedra, edges with six equivalent CoTa6Co6 cuboctahedra, and faces with eighteen equivalent CoTa7Co5 cuboctahedra.