DOE OSTI2020
K3Ho(PO4)2 crystallizes in the monoclinic P2_1/m space group. The structure is three-dimensional. there are three inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a 10-coordinate geometry to ten O2- atoms. There are a spread of K–O bond distances ranging from 2.74–3.12 Å. In the second K1+ site, K1+ is bonded in a 1-coordinate geometry to eleven O2- atoms. There are a spread of K–O bond distances ranging from 2.62–3.36 Å. In the third K1+ site, K1+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of K–O bond distances ranging from 2.70–3.07 Å. Ho3+ is bonded to seven O2- atoms to form distorted HoO7 pentagonal bipyramids that share corners with five PO4 tetrahedra and an edgeedge with one PO4 tetrahedra. There are a spread of Ho–O bond distances ranging from 2.25–2.56 Å. There are two inequivalent P5+ sites. In the first P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two equivalent HoO7 pentagonal bipyramids and an edgeedge with one HoO7 pentagonal bipyramid. There is one shorter (1.55 Å) and three longer (1.56 Å) P–O bond length. In the second P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with three equivalent HoO7 pentagonal bipyramids. There are a spread of P–O bond distances ranging from 1.54–1.57 Å. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a 1-coordinate geometry to one K1+, one Ho3+, and one P5+ atom. In the second O2- site, O2- is bonded in a distorted single-bond geometry to four K1+, one Ho3+, and one P5+ atom. In the third O2- site, O2- is bonded in a 1-coordinate geometry to four K1+, one Ho3+, and one P5+ atom. In the fourth O2- site, O2- is bonded in a 2-coordinate geometry to four K1+, one Ho3+, and one P5+ atom. In the fifth O2- site, O2- is bonded in a distorted single-bond geometry to four K1+, one Ho3+, and one P5+ atom. In the sixth O2- site, O2- is bonded in a distorted single-bond geometry to five K1+ and one P5+ atom.