DOE OSTI2020
CsNiF3 is (Cubic) Perovskite-like structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. there are two inequivalent Cs1+ sites. In the first Cs1+ site, Cs1+ is bonded to twelve F1- atoms to form CsF12 cuboctahedra that share corners with twelve CsF12 cuboctahedra, faces with six equivalent CsF12 cuboctahedra, and faces with eight NiF6 octahedra. All Cs–F bond lengths are 3.07 Å. In the second Cs1+ site, Cs1+ is bonded to twelve F1- atoms to form CsF12 cuboctahedra that share corners with nine CsF12 cuboctahedra, corners with three equivalent NiF6 octahedra, faces with seven CsF12 cuboctahedra, and faces with seven NiF6 octahedra. The corner-sharing octahedral tilt angles are 5°. There are nine shorter (3.06 Å) and three longer (3.10 Å) Cs–F bond lengths. There are two inequivalent Ni2+ sites. In the first Ni2+ site, Ni2+ is bonded to six equivalent F1- atoms to form NiF6 octahedra that share corners with six equivalent NiF6 octahedra and faces with eight CsF12 cuboctahedra. The corner-sharing octahedral tilt angles are 2°. All Ni–F bond lengths are 2.10 Å. In the second Ni2+ site, Ni2+ is bonded to six F1- atoms to form NiF6 octahedra that share corners with three equivalent CsF12 cuboctahedra, corners with three equivalent NiF6 octahedra, faces with seven CsF12 cuboctahedra, and a faceface with one NiF6 octahedra. The corner-sharing octahedral tilt angles are 2°. There are three shorter (2.07 Å) and three longer (2.09 Å) Ni–F bond lengths. There are two inequivalent F1- sites. In the first F1- site, F1- is bonded in a distorted L-shaped geometry to four Cs1+ and two equivalent Ni2+ atoms. In the second F1- site, F1- is bonded in a distorted linear geometry to four Cs1+ and two Ni2+ atoms.