Materials Data on Y2Hf2O7 by Materials Project

Abstract

Y2Hf2O7 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. Y3+ is bonded to six O2- atoms to form distorted YO6 pentagonal pyramids that share corners with four equivalent HfO5 trigonal bipyramids, edges with three equivalent YO6 pentagonal pyramids, and edges with two equivalent HfO5 trigonal bipyramids. There are a spread of Y–O bond distances ranging from 2.22–2.37 Å. Hf4+ is bonded to five O2- atoms to form distorted HfO5 trigonal bipyramids that share corners with four equivalent YO6 pentagonal pyramids, a cornercorner with one HfO5 trigonal bipyramid, edges with two equivalent YO6 pentagonal pyramids, and an edgeedge with one HfO5 trigonal bipyramid. There are a spread of Hf–O bond distances ranging from 1.95–2.32 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to two equivalent Y3+ and one Hf4+ atom. In the second O2- site, O2- is bonded to two equivalent Y3+ and two equivalent Hf4+ atoms to form distorted edge-sharing OY2Hf2 trigonal pyramids. In the third O2- site, O2- is bonded in a linear geometry to two equivalent Hf4+ atoms.