DOE OSTI2020
HoGaO3 crystallizes in the hexagonal P6_3cm space group. The structure is three-dimensional. there are two inequivalent Ho3+ sites. In the first Ho3+ site, Ho3+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Ho–O bond distances ranging from 2.27–2.49 Å. In the second Ho3+ site, Ho3+ is bonded to seven O2- atoms to form distorted HoO7 pentagonal bipyramids that share corners with three equivalent GaO5 trigonal bipyramids and edges with three equivalent GaO5 trigonal bipyramids. There are a spread of Ho–O bond distances ranging from 2.28–2.38 Å. Ga3+ is bonded to five O2- atoms to form GaO5 trigonal bipyramids that share a cornercorner with one HoO7 pentagonal bipyramid, corners with six equivalent GaO5 trigonal bipyramids, and an edgeedge with one HoO7 pentagonal bipyramid. There are a spread of Ga–O bond distances ranging from 1.90–2.05 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded to three Ho3+ and one Ga3+ atom to form OHo3Ga tetrahedra that share corners with ten OHo3Ga tetrahedra, corners with two equivalent OHoGa3 trigonal pyramids, edges with three equivalent OHo3Ga tetrahedra, and edges with two equivalent OHoGa3 trigonal pyramids. In the second O2- site, O2- is bonded to three Ho3+ and one Ga3+ atom to form distorted OHo3Ga tetrahedra that share corners with ten OHo3Ga tetrahedra, corners with four equivalent OHoGa3 trigonal pyramids, edges with three equivalent OHo3Ga tetrahedra, and an edgeedge with one OHoGa3 trigonal pyramid. In the third O2- site, O2- is bonded to one Ho3+ and three equivalent Ga3+ atoms to form distorted OHoGa3 trigonal pyramids that share corners with six equivalent OHo3Ga tetrahedra, corners with six OHoGa3 trigonal pyramids, and edges with three equivalent OHo3Ga tetrahedra. In the fourth O2- site, O2- is bonded to one Ho3+ and three equivalent Ga3+ atoms to form OHoGa3 trigonal pyramids that share corners with six equivalent OHo3Ga tetrahedra, corners with six equivalent OHoGa3 trigonal pyramids, and edges with three equivalent OHo3Ga tetrahedra.