Materials Data on NaBe2Tl3F8 by Materials Project

Abstract

NaBe2Tl3F8 crystallizes in the trigonal P-3m1 space group. The structure is three-dimensional. Na1+ is bonded to six equivalent F1- atoms to form NaF6 octahedra that share corners with six equivalent BeF4 tetrahedra and faces with two equivalent TlF12 cuboctahedra. All Na–F bond lengths are 2.39 Å. Be2+ is bonded to four F1- atoms to form BeF4 tetrahedra that share corners with three equivalent NaF6 octahedra and edges with three equivalent TlF12 cuboctahedra. The corner-sharing octahedral tilt angles are 17°. There is one shorter (1.54 Å) and three longer (1.59 Å) Be–F bond length. There are two inequivalent Tl1+ sites. In the first Tl1+ site, Tl1+ is bonded in a 1-coordinate geometry to ten F1- atoms. There are a spread of Tl–F bond distances ranging from 2.59–3.25 Å. In the second Tl1+ site, Tl1+ is bonded to twelve F1- atoms to form TlF12 cuboctahedra that share edges with six equivalent TlF12 cuboctahedra, edges with six equivalent BeF4 tetrahedra, and faces with two equivalent NaF6 octahedra. There are six shorter (3.00 Å) and six longer (3.39 Å) Tl–F bond lengths. There are two inequivalent F1- sites. In the first F1- site, F1- is bonded in a distorted single-bond geometry to one Be2+ and four Tl1+ atoms. In the second F1- site, F1- is bonded in a 1-coordinate geometry to one Na1+, one Be2+, and four Tl1+ atoms.