Materials Data on K2Ca2C2O3F2 by Materials Project

Abstract

K2Ca2C2O3F2 crystallizes in the orthorhombic Cmc2_1 space group. The structure is three-dimensional. K1+ is bonded in a 6-coordinate geometry to three O2- and three equivalent F1- atoms. There are a spread of K–O bond distances ranging from 2.80–2.92 Å. There are a spread of K–F bond distances ranging from 2.76–2.82 Å. There are two inequivalent Ca2+ sites. In the first Ca2+ site, Ca2+ is bonded to three O2- and two equivalent F1- atoms to form corner-sharing CaO3F2 trigonal bipyramids. There are one shorter (2.35 Å) and two longer (2.39 Å) Ca–O bond lengths. Both Ca–F bond lengths are 2.28 Å. In the second Ca2+ site, Ca2+ is bonded to three O2- and two equivalent F1- atoms to form distorted corner-sharing CaO3F2 trigonal bipyramids. There are a spread of Ca–O bond distances ranging from 2.37–2.55 Å. Both Ca–F bond lengths are 2.34 Å. There are two inequivalent C1+ sites. In the first C1+ site, C1+ is bonded in a bent 120 degrees geometry to two O2- atoms. There is one shorter (1.31 Å) and one longer (1.32 Å) C–O bond length. In the second C1+ site, C1+ is bonded in a single-bond geometry to one O2- atom. The C–O bond length is 1.32 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a 5-coordinate geometry to two equivalent K1+, two Ca2+, and one C1+ atom. In the second O2- site, O2- is bonded to two equivalent K1+, two equivalent Ca2+, and one C1+ atom to form distorted OK2Ca2C trigonal bipyramids that share corners with two equivalent OK2Ca2C trigonal bipyramids, corners with two equivalent FK3Ca2 trigonal bipyramids, and edges with four equivalent FK3Ca2 trigonal bipyramids. In the third O2- site, O2- is bonded in a 1-coordinate geometry to two equivalent K1+, two equivalent Ca2+, and one C1+ atom. F1- is bonded to three equivalent K1+ and two Ca2+ atoms to form FK3Ca2 trigonal bipyramids that share a cornercorner with one OK2Ca2C trigonal bipyramid, corners with eight equivalent FK3Ca2 trigonal bipyramids, and edges with two equivalent OK2Ca2C trigonal bipyramids.