DOE OSTI2020
CaNiF5 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are two inequivalent Ca2+ sites. In the first Ca2+ site, Ca2+ is bonded to seven F1- atoms to form CaF7 pentagonal bipyramids that share corners with four NiF6 octahedra, edges with two NiF6 octahedra, and edges with two equivalent CaF7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 2–38°. There are a spread of Ca–F bond distances ranging from 2.25–2.44 Å. In the second Ca2+ site, Ca2+ is bonded to seven F1- atoms to form CaF7 pentagonal bipyramids that share corners with four NiF6 octahedra, edges with two NiF6 octahedra, and edges with two equivalent CaF7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 2–38°. There are a spread of Ca–F bond distances ranging from 2.25–2.42 Å. There are two inequivalent Ni3+ sites. In the first Ni3+ site, Ni3+ is bonded to six F1- atoms to form NiF6 octahedra that share corners with two equivalent NiF6 octahedra, corners with four CaF7 pentagonal bipyramids, and edges with two CaF7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 31°. There are a spread of Ni–F bond distances ranging from 1.79–2.02 Å. In the second Ni3+ site, Ni3+ is bonded to six F1- atoms to form NiF6 octahedra that share corners with two equivalent NiF6 octahedra, corners with four CaF7 pentagonal bipyramids, and edges with two CaF7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 31°. There are a spread of Ni–F bond distances ranging from 1.79–2.00 Å. There are ten inequivalent F1- sites. In the first F1- site, F1- is bonded in a 3-coordinate geometry to one Ca2+ and two Ni3+ atoms. In the second F1- site, F1- is bonded in a 3-coordinate geometry to one Ca2+ and two Ni3+ atoms. In the third F1- site, F1- is bonded in a linear geometry to one Ca2+ and one Ni3+ atom. In the fourth F1- site, F1- is bonded in a linear geometry to one Ca2+ and one Ni3+ atom. In the fifth F1- site, F1- is bonded in a 3-coordinate geometry to two Ca2+ and one Ni3+ atom. In the sixth F1- site, F1- is bonded in a 3-coordinate geometry to two Ca2+ and one Ni3+ atom. In the seventh F1- site, F1- is bonded in a 3-coordinate geometry to two Ca2+ and one Ni3+ atom. In the eighth F1- site, F1- is bonded in a 3-coordinate geometry to two Ca2+ and one Ni3+ atom. In the ninth F1- site, F1- is bonded in a linear geometry to one Ca2+ and one Ni3+ atom. In the tenth F1- site, F1- is bonded in a linear geometry to one Ca2+ and one Ni3+ atom.