DOE OSTI2020
Ho3(RuSi3)4 crystallizes in the orthorhombic Cmce space group. The structure is three-dimensional. there are two inequivalent Ho3+ sites. In the first Ho3+ site, Ho3+ is bonded to twelve Si2- atoms to form HoSi12 cuboctahedra that share corners with four equivalent HoSi12 cuboctahedra, corners with four equivalent RuSi7 hexagonal pyramids, edges with eight equivalent HoSi12 cuboctahedra, and faces with four equivalent RuSi7 hexagonal pyramids. There are four shorter (3.03 Å) and eight longer (3.09 Å) Ho–Si bond lengths. In the second Ho3+ site, Ho3+ is bonded to twelve Si2- atoms to form distorted HoSi12 cuboctahedra that share corners with four equivalent HoSi12 cuboctahedra, corners with four equivalent RuSi7 hexagonal pyramids, edges with four equivalent HoSi12 cuboctahedra, edges with two equivalent RuSi7 hexagonal pyramids, and faces with four equivalent HoSi12 cuboctahedra. There are a spread of Ho–Si bond distances ranging from 2.97–3.23 Å. There are two inequivalent Ru+3.75+ sites. In the first Ru+3.75+ site, Ru+3.75+ is bonded to seven Si2- atoms to form distorted RuSi7 hexagonal pyramids that share corners with six HoSi12 cuboctahedra, corners with four equivalent RuSi7 hexagonal pyramids, edges with two equivalent HoSi12 cuboctahedra, an edgeedge with one RuSi7 hexagonal pyramid, and faces with two equivalent HoSi12 cuboctahedra. There are a spread of Ru–Si bond distances ranging from 2.37–2.52 Å. In the second Ru+3.75+ site, Ru+3.75+ is bonded in a 5-coordinate geometry to five Si2- atoms. There are a spread of Ru–Si bond distances ranging from 2.32–2.41 Å. There are four inequivalent Si2- sites. In the first Si2- site, Si2- is bonded in a 1-coordinate geometry to four equivalent Ho3+, one Ru+3.75+, and four Si2- atoms. All Si–Si bond lengths are 2.47 Å. In the second Si2- site, Si2- is bonded in a 9-coordinate geometry to two equivalent Ho3+, three equivalent Ru+3.75+, and four Si2- atoms. There are two shorter (2.63 Å) and two longer (2.64 Å) Si–Si bond lengths. In the third Si2- site, Si2- is bonded in a 2-coordinate geometry to three Ho3+, two Ru+3.75+, and four Si2- atoms. There are one shorter (2.56 Å) and one longer (2.71 Å) Si–Si bond lengths. In the fourth Si2- site, Si2- is bonded in a 2-coordinate geometry to three Ho3+, two Ru+3.75+, and four Si2- atoms.