Materials Data on Ho2TiO5 by Materials Project

Abstract

Ho2TiO5 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. there are two inequivalent Ho3+ sites. In the first Ho3+ site, Ho3+ is bonded to seven O2- atoms to form distorted HoO7 hexagonal pyramids that share corners with two equivalent HoO7 hexagonal pyramids, corners with three equivalent TiO5 trigonal bipyramids, edges with five HoO7 hexagonal pyramids, and edges with two equivalent TiO5 trigonal bipyramids. There are a spread of Ho–O bond distances ranging from 2.27–2.38 Å. In the second Ho3+ site, Ho3+ is bonded to seven O2- atoms to form distorted HoO7 hexagonal pyramids that share corners with two equivalent HoO7 hexagonal pyramids, a cornercorner with one TiO5 trigonal bipyramid, edges with seven HoO7 hexagonal pyramids, and edges with two equivalent TiO5 trigonal bipyramids. There are a spread of Ho–O bond distances ranging from 2.34–2.36 Å. Ti4+ is bonded to five O2- atoms to form distorted TiO5 trigonal bipyramids that share corners with four HoO7 hexagonal pyramids, corners with two equivalent TiO5 trigonal bipyramids, and edges with four HoO7 hexagonal pyramids. There are a spread of Ti–O bond distances ranging from 1.79–1.97 Å. There are five inequivalent O2- sites. In the first O2- site, O2- is bonded to four Ho3+ atoms to form a mixture of edge and corner-sharing OHo4 tetrahedra. In the second O2- site, O2- is bonded in a distorted trigonal planar geometry to two equivalent Ho3+ and one Ti4+ atom. In the third O2- site, O2- is bonded to three Ho3+ and one Ti4+ atom to form distorted OHo3Ti tetrahedra that share corners with nine OHo4 tetrahedra and edges with five OHo3Ti tetrahedra. In the fourth O2- site, O2- is bonded to two Ho3+ and two equivalent Ti4+ atoms to form distorted OHo2Ti2 tetrahedra that share corners with six OHo4 tetrahedra and edges with five OHo3Ti tetrahedra. In the fifth O2- site, O2- is bonded to three Ho3+ and one Ti4+ atom to form OHo3Ti tetrahedra that share corners with nine OHo4 tetrahedra and edges with four OHo3Ti tetrahedra.