Materials Data on USiNi by Materials Project
UNiSi crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. U3+ is bonded to two equivalent U3+ and five equivalent Si4- atoms to form distorted UU2Si5 pentagonal bipyramids that share corners with eight equivalent UU2Si5 pentagonal bipyramids, corners with eight equivalent NiSi4 tetrahedra, edges with four equivalent UU2Si5 pentagonal bipyramids, edges with six equivalent NiSi4 tetrahedra, and faces with two equivalent UU2Si5 pentagonal bipyramids. Both U–U bond lengths are 2.61 Å. There are one shorter (2.85 Å) and four longer (2.89 Å) U–Si bond lengths. Ni1+ is bonded to four equivalent Si4- atoms to form NiSi4 tetrahedra that share corners with eight equivalent UU2Si5 pentagonal bipyramids, corners with eight equivalent NiSi4 tetrahedra, edges with six equivalent UU2Si5 pentagonal bipyramids, and edges with two equivalent NiSi4 tetrahedra. There are a spread of Ni–Si bond distances ranging from 2.35–2.49 Å. Si4- is bonded in a 9-coordinate geometry to five equivalent U3+ and four equivalent Ni1+ atoms.