Materials Data on K2Ca2(CO3)3 by Materials Project
K2Ca2(CO3)3 crystallizes in the trigonal R3 space group. The structure is three-dimensional. there are two inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a 6-coordinate geometry to six O2- atoms. There are three shorter (2.76 Å) and three longer (2.78 Å) K–O bond lengths. In the second K1+ site, K1+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of K–O bond distances ranging from 2.73–3.10 Å. There are two inequivalent Ca2+ sites. In the first Ca2+ site, Ca2+ is bonded to seven O2- atoms to form distorted edge-sharing CaO7 pentagonal bipyramids. There are a spread of Ca–O bond distances ranging from 2.40–2.64 Å. In the second Ca2+ site, Ca2+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of Ca–O bond distances ranging from 2.45–2.59 Å. There are two inequivalent C4+ sites. In the first C4+ site, C4+ is bonded in a trigonal planar geometry to three O2- atoms. There are a spread of C–O bond distances ranging from 1.29–1.31 Å. In the second C4+ site, C4+ is bonded in a trigonal planar geometry to three O2- atoms. All C–O bond lengths are 1.30 Å. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a 1-coordinate geometry to one K1+, two Ca2+, and one C4+ atom. In the second O2- site, O2- is bonded in a distorted single-bond geometry to one K1+, two equivalent Ca2+, and one C4+ atom. In the third O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent K1+, one Ca2+, and one C4+ atom. In the fourth O2- site, O2- is bonded in a distorted single-bond geometry to three K1+, one Ca2+, and one C4+ atom. In the fifth O2- site, O2- is bonded in a distorted single-bond geometry to one K1+, two Ca2+, and one C4+ atom. In the sixth O2- site, O2- is bonded in a 1-coordinate geometry to one K1+, two equivalent Ca2+, and one C4+ atom.