DOE OSTI2020
CaCO4 crystallizes in the trigonal P3_1 space group. The structure is three-dimensional. there are three inequivalent Ca sites. In the first Ca site, Ca is bonded to seven O atoms to form corner-sharing CaO7 pentagonal bipyramids. There are a spread of Ca–O bond distances ranging from 2.34–2.50 Å. In the second Ca site, Ca is bonded to seven O atoms to form corner-sharing CaO7 pentagonal bipyramids. There are a spread of Ca–O bond distances ranging from 2.35–2.51 Å. In the third Ca site, Ca is bonded to seven O atoms to form distorted corner-sharing CaO7 pentagonal bipyramids. There are a spread of Ca–O bond distances ranging from 2.34–2.47 Å. There are three inequivalent C sites. In the first C site, C is bonded in a trigonal planar geometry to three O atoms. There is two shorter (1.29 Å) and one longer (1.31 Å) C–O bond length. In the second C site, C is bonded in a trigonal planar geometry to three O atoms. There is two shorter (1.29 Å) and one longer (1.31 Å) C–O bond length. In the third C site, C is bonded in a trigonal planar geometry to three O atoms. There is two shorter (1.29 Å) and one longer (1.30 Å) C–O bond length. There are twelve inequivalent O sites. In the first O site, O is bonded in a 3-coordinate geometry to two Ca and one C atom. In the second O site, O is bonded in a 3-coordinate geometry to two Ca and one C atom. In the third O site, O is bonded in a bent 150 degrees geometry to two equivalent Ca atoms. In the fourth O site, O is bonded in a 3-coordinate geometry to two Ca and one C atom. In the fifth O site, O is bonded in a bent 150 degrees geometry to two equivalent Ca atoms. In the sixth O site, O is bonded in a distorted bent 150 degrees geometry to one Ca and one C atom. In the seventh O site, O is bonded in a distorted bent 150 degrees geometry to one Ca and one C atom. In the eighth O site, O is bonded in a 1-coordinate geometry to two Ca and one C atom. In the ninth O site, O is bonded in a bent 150 degrees geometry to two equivalent Ca atoms. In the tenth O site, O is bonded in a distorted bent 150 degrees geometry to one Ca and one C atom. In the eleventh O site, O is bonded in a 3-coordinate geometry to two Ca and one C atom. In the twelfth O site, O is bonded in a 3-coordinate geometry to two Ca and one C atom.