Materials Data on TiCoNi2 by Materials Project
TiCoNi2 is beta Cu3Ti-derived structured and crystallizes in the orthorhombic Amm2 space group. The structure is three-dimensional. there are three inequivalent Ti sites. In the first Ti site, Ti is bonded to six Co and six Ni atoms to form TiCo6Ni6 cuboctahedra that share corners with twelve TiCo6Ni6 cuboctahedra, edges with eight CoTi4Co4Ni4 cuboctahedra, edges with sixteen NiTi4Co2Ni6 cuboctahedra, faces with six equivalent TiCo4Ni8 cuboctahedra, faces with six CoTi4Co4Ni4 cuboctahedra, and faces with six NiTi4Co3Ni5 cuboctahedra. There are four shorter (2.54 Å) and two longer (2.55 Å) Ti–Co bond lengths. All Ti–Ni bond lengths are 2.54 Å. In the second Ti site, Ti is bonded to two equivalent Co and ten Ni atoms to form TiCo2Ni10 cuboctahedra that share corners with twelve TiCo6Ni6 cuboctahedra, edges with eight CoTi4Co4Ni4 cuboctahedra, edges with sixteen NiTi4Co2Ni6 cuboctahedra, faces with two equivalent CoTi4Ni8 cuboctahedra, faces with six equivalent TiCo4Ni8 cuboctahedra, and faces with ten NiTi4Co2Ni6 cuboctahedra. Both Ti–Co bond lengths are 2.54 Å. There are eight shorter (2.54 Å) and two longer (2.55 Å) Ti–Ni bond lengths. In the third Ti site, Ti is bonded to four Co and eight Ni atoms to form TiCo4Ni8 cuboctahedra that share corners with six equivalent TiCo4Ni8 cuboctahedra, corners with twelve NiTi4Co3Ni5 cuboctahedra, edges with eight CoTi4Co4Ni4 cuboctahedra, edges with ten NiTi4Co2Ni6 cuboctahedra, faces with four CoTi4Co4Ni4 cuboctahedra, faces with eight TiCo6Ni6 cuboctahedra, and faces with eight NiTi4Co2Ni6 cuboctahedra. There are three shorter (2.55 Å) and one longer (2.59 Å) Ti–Co bond lengths. There are a spread of Ti–Ni bond distances ranging from 2.54–2.59 Å. There are three inequivalent Co sites. In the first Co site, Co is bonded to four Ti, four equivalent Co, and four equivalent Ni atoms to form distorted CoTi4Co4Ni4 cuboctahedra that share corners with twelve CoTi4Co4Ni4 cuboctahedra, edges with four equivalent CoTi4Co4Ni4 cuboctahedra, edges with eight TiCo6Ni6 cuboctahedra, edges with twelve NiTi4Co2Ni6 cuboctahedra, faces with four TiCo6Ni6 cuboctahedra, faces with four equivalent CoTi4Co4Ni4 cuboctahedra, and faces with ten NiTi4Co3Ni5 cuboctahedra. There are two shorter (2.45 Å) and two longer (2.64 Å) Co–Co bond lengths. All Co–Ni bond lengths are 2.53 Å. In the second Co site, Co is bonded to four Ti, four Co, and four Ni atoms to form distorted CoTi4Co4Ni4 cuboctahedra that share corners with six equivalent CoTi4Co4Ni4 cuboctahedra, corners with six equivalent NiTi4Co2Ni6 cuboctahedra, edges with six CoTi4Co4Ni4 cuboctahedra, edges with eight TiCo6Ni6 cuboctahedra, edges with ten NiTi4Co2Ni6 cuboctahedra, faces with four TiCo6Ni6 cuboctahedra, faces with four CoTi4Co4Ni4 cuboctahedra, and faces with ten NiTi4Co3Ni5 cuboctahedra. There are one shorter (2.44 Å) and one longer (2.63 Å) Co–Co bond lengths. All Co–Ni bond lengths are 2.52 Å. In the third Co site, Co is bonded to four Ti and eight Ni atoms to form CoTi4Ni8 cuboctahedra that share corners with twelve CoTi4Co4Ni4 cuboctahedra, edges with four equivalent CoTi4Co4Ni4 cuboctahedra, edges with eight TiCo6Ni6 cuboctahedra, edges with twelve NiTi4Co2Ni6 cuboctahedra, faces with four TiCo2Ni10 cuboctahedra, and faces with fourteen NiTi4Co2Ni6 cuboctahedra. There are a spread of Co–Ni bond distances ranging from 2.46–2.63 Å. There are three inequivalent Ni sites. In the first Ni site, Ni is bonded to four Ti, two equivalent Co, and six Ni atoms to form distorted NiTi4Co2Ni6 cuboctahedra that share corners with six equivalent CoTi4Co4Ni4 cuboctahedra, corners with six equivalent NiTi4Co2Ni6 cuboctahedra, edges with six CoTi4Co4Ni4 cuboctahedra, edges with eight TiCo6Ni6 cuboctahedra, edges with ten NiTi4Co2Ni6 cuboctahedra, faces with two equivalent CoTi4Ni8 cuboctahedra, faces with four TiCo2Ni10 cuboctahedra, and faces with twelve NiTi4Co2Ni6 cuboctahedra. There are a spread of Ni–Ni bond distances ranging from 2.46–2.62 Å. In the second Ni site, Ni is bonded to four Ti, three Co, and five Ni atoms to form distorted NiTi4Co3Ni5 cuboctahedra that share corners with four equivalent TiCo4Ni8 cuboctahedra, corners with fourteen NiTi4Co2Ni6 cuboctahedra, edges with six TiCo6Ni6 cuboctahedra, edges with six CoTi4Co4Ni4 cuboctahedra, edges with six NiTi4Co2Ni6 cuboctahedra, faces with four TiCo6Ni6 cuboctahedra, faces with six CoTi4Co4Ni4 cuboctahedra, and faces with ten NiTi4Co2Ni6 cuboctahedra. There are a spread of Ni–Ni bond distances ranging from 2.53–2.55 Å. In the third Ni site, Ni is bonded to four Ti, two equivalent Co, and six Ni atoms to form distorted NiTi4Co2Ni6 cuboctahedra that share corners with four equivalent TiCo4Ni8 cuboctahedra, corners with fourteen NiTi4Co2Ni6 cuboctahedra, edges with four equivalent CoTi4Co4Ni4 cuboctahedra, edges with six TiCo6Ni6 cuboctahedra, edges with eight NiTi4Co2Ni6 cuboctahedra, faces with four TiCo6Ni6 cuboctahedra, faces with eight CoTi4Co4Ni4 cuboctahedra, and faces with eight NiTi4Co2Ni6 cuboctahedra.