Materials Data on Ho2Mg2O5 by Materials Project

Mg2Ho2O5 crystallizes in the tetragonal P4/mmm space group. The structure is three-dimensional. Mg2+ is bonded to five O2- atoms to form MgO5 square pyramids that share corners with five equivalent MgO5 square pyramids and faces with four equivalent HoO12 cuboctahedra. There is one shorter (1.89 Å) and four longer (1.95 Å) Mg–O bond length. There are two inequivalent Ho3+ sites. In the first Ho3+ site, Ho3+ is bonded in a body-centered cubic geometry to eight equivalent O2- atoms. All Ho–O bond lengths are 2.40 Å. In the second Ho3+ site, Ho3+ is bonded to twelve O2- atoms to form HoO12 cuboctahedra that share corners with four equivalent HoO12 cuboctahedra, faces with four equivalent HoO12 cuboctahedra, and faces with eight equivalent MgO5 square pyramids. There are four shorter (2.73 Å) and eight longer (2.91 Å) Ho–O bond lengths. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Mg2+ and four Ho3+ atoms. In the second O2- site, O2- is bonded in a distorted linear geometry to two equivalent Mg2+ and four equivalent Ho3+ atoms.