Materials Data on YZr2Co9 by Materials Project
YZr2Co9 is Frank-Kasper $\mu$ Phase-derived structured and crystallizes in the trigonal R3m space group. The structure is three-dimensional. Y is bonded in a 12-coordinate geometry to four Zr and twelve Co atoms. There are three shorter (3.11 Å) and one longer (3.35 Å) Y–Zr bond lengths. There are a spread of Y–Co bond distances ranging from 2.81–3.05 Å. There are two inequivalent Zr sites. In the first Zr site, Zr is bonded in a 9-coordinate geometry to three equivalent Y and twelve Co atoms. There are a spread of Zr–Co bond distances ranging from 2.77–3.11 Å. In the second Zr site, Zr is bonded in a distorted hexagonal planar geometry to one Y and eighteen Co atoms. There are a spread of Zr–Co bond distances ranging from 2.80–3.11 Å. There are five inequivalent Co sites. In the first Co site, Co is bonded to two equivalent Y, three Zr, and seven Co atoms to form distorted CoY2Zr3Co7 cuboctahedra that share corners with twenty-one CoY2Zr3Co7 cuboctahedra, edges with twelve CoZr3Co6 cuboctahedra, and faces with sixteen CoY2Zr3Co7 cuboctahedra. There are a spread of Co–Co bond distances ranging from 2.39–2.50 Å. In the second Co site, Co is bonded to one Y, four Zr, and seven Co atoms to form distorted CoYZr4Co7 cuboctahedra that share corners with twenty-one CoY2Zr3Co7 cuboctahedra, edges with twelve CoZr3Co6 cuboctahedra, and faces with sixteen CoY2Zr3Co7 cuboctahedra. There are a spread of Co–Co bond distances ranging from 2.39–2.47 Å. In the third Co site, Co is bonded to three equivalent Zr and six Co atoms to form a mixture of distorted edge, corner, and face-sharing CoZr3Co6 cuboctahedra. In the fourth Co site, Co is bonded to three equivalent Zr and six Co atoms to form a mixture of distorted edge, corner, and face-sharing CoZr3Co6 cuboctahedra. In the fifth Co site, Co is bonded to three equivalent Y, three equivalent Zr, and six Co atoms to form CoY3Zr3Co6 cuboctahedra that share corners with eighteen CoY2Zr3Co7 cuboctahedra, edges with six equivalent CoY3Zr3Co6 cuboctahedra, and faces with twenty CoY2Zr3Co7 cuboctahedra.