DOI: 10.17188/1201424
title: Materials Data on Ca2Hf7O16 by Materials Project

description: Ca2Hf7O16 crystallizes in the trigonal R-3 space group. The structure is three-dimensional. there are four inequivalent Ca2+ sites. In the first Ca2+ site, Ca2+ is bonded in a body-centered cubic geometry to eight O2- atoms. There are a spread of Ca–O bond distances ranging from 2.46–2.58 Å. In the second Ca2+ site, Ca2+ is bonded in a body-centered cubic geometry to eight O2- atoms. There are a spread of Ca–O bond distances ranging from 2.46–2.58 Å. In the third Ca2+ site, Ca2+ is bonded in a body-centered cubic geometry to eight O2- atoms. There are a spread of Ca–O bond distances ranging from 2.46–2.58 Å. In the fourth Ca2+ site, Ca2+ is bonded in a body-centered cubic geometry to eight O2- atoms. There are a spread of Ca–O bond distances ranging from 2.46–2.58 Å. There are seven inequivalent Hf4+ sites. In the first 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 43°. There are a spread of Hf–O bond distances ranging from 2.03–2.28 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 43°. There are a spread of Hf–O bond distances ranging from 2.03–2.28 Å. In the third 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 fourth 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 43°. There are a spread of Hf–O bond distances ranging from 2.03–2.28 Å. In the fifth 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 sixth 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 43°. There are a spread of Hf–O bond distances ranging from 2.03–2.28 Å. In the seventh 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 in a 4-coordinate geometry to two Ca2+ and two Hf4+ atoms. In the second O2- site, O2- is bonded to one Ca2+ and three equivalent Hf4+ atoms to form a mixture of distorted edge and corner-sharing OCaHf3 tetrahedra. In the third O2- site, O2- is bonded to one Ca2+ and three equivalent Hf4+ atoms to form a mixture of edge and corner-sharing OCaHf3 tetrahedra. In the fourth O2- site, O2- is bonded to four Hf4+ atoms to form a mixture of distorted edge and corner-sharing OHf4 tetrahedra.