Materials Data on Sr2Hf7O16 by Materials Project

Abstract

Sr2Hf7O16 crystallizes in the trigonal R-3 space group. The structure is three-dimensional. there are three inequivalent Sr2+ sites. In the first Sr2+ site, Sr2+ is bonded in a distorted body-centered cubic geometry to eight O2- atoms. There are a spread of Sr–O bond distances ranging from 2.57–2.64 Å. In the second Sr2+ site, Sr2+ is bonded in a distorted body-centered cubic geometry to eight O2- atoms. There are a spread of Sr–O bond distances ranging from 2.57–2.64 Å. In the third Sr2+ site, Sr2+ is bonded in a distorted body-centered cubic geometry to eight O2- atoms. There are a spread of Sr–O bond distances ranging from 2.57–2.64 Å. There are six inequivalent Hf4+ sites. In the first Hf4+ site, Hf4+ is bonded to six equivalent O2- atoms to form corner-sharing HfO6 octahedra. All Hf–O bond lengths are 2.10 Å. In the second Hf4+ site, Hf4+ is bonded to seven O2- atoms to form distorted HfO7 pentagonal bipyramids that share a cornercorner with one HfO6 octahedra, corners with two equivalent HfO7 pentagonal bipyramids, and edges with seven HfO7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 40°. There are a spread of Hf–O bond distances ranging from 2.04–2.30 Å. In the third Hf4+ site, Hf4+ is bonded to seven O2- atoms to form distorted HfO7 pentagonal bipyramids that share a cornercorner with one HfO6 octahedra, corners with two equivalent HfO7 pentagonal bipyramids, and edges with seven HfO7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 40°. There are a spread of Hf–O bond distances ranging from 2.04–2.30 Å. In the fourth Hf4+ site, Hf4+ is bonded to six equivalent O2- atoms to form corner-sharing HfO6 octahedra. All Hf–O bond lengths are 2.10 Å. In the fifth Hf4+ site, Hf4+ is bonded to seven O2- atoms to form distorted HfO7 pentagonal bipyramids that share a cornercorner with one HfO6 octahedra, corners with two equivalent HfO7 pentagonal bipyramids, and edges with seven equivalent HfO7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 40°. There are a spread of Hf–O bond distances ranging from 2.04–2.30 Å. In the sixth Hf4+ site, Hf4+ is bonded to six equivalent O2- atoms to form corner-sharing HfO6 octahedra. All Hf–O bond lengths are 2.10 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded to one Sr2+ and three equivalent Hf4+ atoms to form distorted OSrHf3 tetrahedra that share corners with ten OSrHf3 tetrahedra and edges with three equivalent OHf4 tetrahedra. In the second O2- site, O2- is bonded to one Sr2+ and three equivalent Hf4+ atoms to form distorted OSrHf3 tetrahedra that share corners with ten OSrHf3 tetrahedra and edges with three equivalent OHf4 tetrahedra. In the third O2- site, O2- is bonded in a 4-coordinate geometry to two Sr2+ and two Hf4+ atoms. In the fourth O2- site, O2- is bonded to four Hf4+ atoms to form a mixture of distorted edge and corner-sharing OHf4 tetrahedra.