Materials Data on K3TaO2F7 by Materials Project

Abstract

K3TaO2F7 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. there are two inequivalent K sites. In the first K site, K is bonded in a 4-coordinate geometry to four equivalent F atoms. There are two shorter (2.63 Å) and two longer (2.71 Å) K–F bond lengths. In the second K site, K is bonded in a 8-coordinate geometry to one O and seven F atoms. The K–O bond length is 3.00 Å. There are a spread of K–F bond distances ranging from 2.51–3.19 Å. Ta is bonded in a distorted pentagonal bipyramidal geometry to two equivalent O and five F atoms. Both Ta–O bond lengths are 2.12 Å. There are a spread of Ta–F bond distances ranging from 1.92–1.95 Å. O is bonded in a 3-coordinate geometry to one K, one Ta, and one O atom. The O–O bond length is 1.35 Å. There are five inequivalent F sites. In the first F site, F is bonded in a single-bond geometry to two equivalent K and one Ta atom. In the second F site, F is bonded in a distorted single-bond geometry to two equivalent K and one Ta atom. In the third F site, F is bonded to four K atoms to form a mixture of distorted edge and corner-sharing FK4 trigonal pyramids. In the fourth F site, F is bonded in a distorted trigonal planar geometry to two equivalent K and one Ta atom. In the fifth F site, F is bonded in a distorted single-bond geometry to two equivalent K and one Ta atom.