Materials Data on Gd2HfO5 by Materials Project

Abstract

Gd2HfO5 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. there are two inequivalent Gd3+ sites. In the first Gd3+ site, Gd3+ is bonded to seven O2- atoms to form distorted GdO7 hexagonal pyramids that share corners with two equivalent GdO7 hexagonal pyramids, corners with three equivalent HfO5 trigonal bipyramids, edges with five GdO7 hexagonal pyramids, and edges with two equivalent HfO5 trigonal bipyramids. There are a spread of Gd–O bond distances ranging from 2.35–2.43 Å. In the second Gd3+ site, Gd3+ is bonded to seven O2- atoms to form distorted GdO7 hexagonal pyramids that share corners with two equivalent GdO7 hexagonal pyramids, a cornercorner with one HfO5 trigonal bipyramid, edges with seven GdO7 hexagonal pyramids, and edges with two equivalent HfO5 trigonal bipyramids. There are a spread of Gd–O bond distances ranging from 2.39–2.45 Å. Hf4+ is bonded to five O2- atoms to form distorted HfO5 trigonal bipyramids that share corners with four GdO7 hexagonal pyramids, corners with two equivalent HfO5 trigonal bipyramids, and edges with four GdO7 hexagonal pyramids. There are a spread of Hf–O bond distances ranging from 1.94–2.05 Å. There are five inequivalent O2- sites. In the first O2- site, O2- is bonded to four Gd3+ atoms to form a mixture of edge and corner-sharing OGd4 tetrahedra. In the second O2- site, O2- is bonded in a distorted trigonal planar geometry to two equivalent Gd3+ and one Hf4+ atom. In the third O2- site, O2- is bonded to three Gd3+ and one Hf4+ atom to form distorted OGd3Hf tetrahedra that share corners with nine OGd4 tetrahedra and edges with five OGd3Hf tetrahedra. In the fourth O2- site, O2- is bonded to two Gd3+ and two equivalent Hf4+ atoms to form distorted OGd2Hf2 tetrahedra that share corners with six OGd4 tetrahedra and edges with five OGd3Hf tetrahedra. In the fifth O2- site, O2- is bonded to three Gd3+ and one Hf4+ atom to form OGd3Hf tetrahedra that share corners with nine OGd4 tetrahedra and edges with four OGd3Hf tetrahedra.