Materials Data on Tm2(Ni7B2)3 by Materials Project
Tm2Ni21B6 crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Tm is bonded to sixteen Ni atoms to form distorted TmNi16 tetrahedra that share edges with six equivalent TmNi16 tetrahedra and faces with four equivalent NiNi12 cuboctahedra. There are four shorter (2.53 Å) and twelve longer (2.93 Å) Tm–Ni bond lengths. There are three inequivalent Ni sites. In the first Ni site, Ni is bonded to one Tm and three equivalent B atoms to form a mixture of distorted edge and corner-sharing NiTmB3 tetrahedra. All Ni–B bond lengths are 2.10 Å. In the second Ni site, Ni is bonded in a distorted bent 150 degrees geometry to two equivalent Tm, one Ni, and two equivalent B atoms. The Ni–Ni bond length is 2.53 Å. Both Ni–B bond lengths are 2.09 Å. In the third Ni site, Ni is bonded to twelve equivalent Ni atoms to form NiNi12 cuboctahedra that share faces with eight equivalent TmNi16 tetrahedra. B is bonded in a 8-coordinate geometry to eight Ni atoms.