Materials Data on Cs2Ca2Be3F12 by Materials Project
Cs2Ca2Be3F12 crystallizes in the cubic P2_13 space group. The structure is three-dimensional. there are two inequivalent Cs1+ sites. In the first Cs1+ site, Cs1+ is bonded in a 12-coordinate geometry to fifteen F1- atoms. There are a spread of Cs–F bond distances ranging from 3.17–3.65 Å. In the second Cs1+ site, Cs1+ is bonded in a 9-coordinate geometry to nine F1- atoms. There are a spread of Cs–F bond distances ranging from 3.13–3.40 Å. There are two inequivalent Ca2+ sites. In the first Ca2+ site, Ca2+ is bonded to six F1- atoms to form CaF6 octahedra that share corners with six equivalent BeF4 tetrahedra. There are three shorter (2.26 Å) and three longer (2.29 Å) Ca–F bond lengths. In the second Ca2+ site, Ca2+ is bonded to six F1- atoms to form CaF6 octahedra that share corners with six equivalent BeF4 tetrahedra. There are three shorter (2.27 Å) and three longer (2.29 Å) Ca–F bond lengths. Be2+ is bonded to four F1- atoms to form BeF4 tetrahedra that share corners with four CaF6 octahedra. The corner-sharing octahedra tilt angles range from 15–49°. There is one shorter (1.56 Å) and three longer (1.57 Å) Be–F bond length. There are four inequivalent F1- sites. In the first F1- site, F1- is bonded in a 2-coordinate geometry to two Cs1+, one Ca2+, and one Be2+ atom. In the second F1- site, F1- is bonded in a distorted bent 150 degrees geometry to one Cs1+, one Ca2+, and one Be2+ atom. In the third F1- site, F1- is bonded in a distorted bent 150 degrees geometry to three Cs1+, one Ca2+, and one Be2+ atom. In the fourth F1- site, F1- is bonded in a 1-coordinate geometry to two Cs1+, one Ca2+, and one Be2+ atom.