DOE OSTI2020
VNiSi crystallizes in the orthorhombic Amm2 space group. The structure is three-dimensional. there are two inequivalent V2+ sites. In the first V2+ site, V2+ is bonded in a 5-coordinate geometry to five Si4- atoms. There are three shorter (2.65 Å) and two longer (2.75 Å) V–Si bond lengths. In the second V2+ site, V2+ is bonded in a 7-coordinate geometry to seven Si4- atoms. There are a spread of V–Si bond distances ranging from 2.69–2.75 Å. There are two inequivalent Ni2+ sites. In the first Ni2+ site, Ni2+ is bonded in a 4-coordinate geometry to four Si4- atoms. There are three shorter (2.26 Å) and one longer (2.33 Å) Ni–Si bond lengths. In the second Ni2+ site, Ni2+ is bonded in a linear geometry to two equivalent Si4- atoms. There are one shorter (2.29 Å) and one longer (2.43 Å) Ni–Si bond lengths. There are three inequivalent Si4- sites. In the first Si4- site, Si4- is bonded to six V2+ and six Ni2+ atoms to form SiV6Ni6 cuboctahedra that share corners with fourteen SiV6Ni6 cuboctahedra, edges with six SiV6Ni6 cuboctahedra, and faces with four equivalent SiV6Si4Ni2 cuboctahedra. In the second Si4- site, Si4- is bonded to six V2+, two equivalent Ni2+, and four Si4- atoms to form SiV6Si4Ni2 cuboctahedra that share corners with eight SiV6Si4Ni2 cuboctahedra, edges with two equivalent SiV6Si4Ni2 cuboctahedra, and faces with ten SiV6Ni6 cuboctahedra. There are a spread of Si–Si bond distances ranging from 2.29–2.46 Å. In the third Si4- site, Si4- is bonded to six V2+, two equivalent Ni2+, and four equivalent Si4- atoms to form SiV6Si4Ni2 cuboctahedra that share corners with six SiV6Ni6 cuboctahedra, edges with six SiV6Ni6 cuboctahedra, and faces with eight equivalent SiV6Si4Ni2 cuboctahedra.