Materials Data on CaCr2(P2O7)2 by Materials Project
CaCr2(P2O7)2 crystallizes in the triclinic P1 space group. The structure is three-dimensional. Ca2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Ca–O bond distances ranging from 2.19–3.02 Å. There are two inequivalent Cr3+ sites. In the first Cr3+ site, Cr3+ is bonded to five O2- atoms to form CrO5 square pyramids that share corners with five PO4 tetrahedra. There are a spread of Cr–O bond distances ranging from 1.96–2.03 Å. In the second Cr3+ site, Cr3+ is bonded to five O2- atoms to form CrO5 trigonal bipyramids that share corners with five PO4 tetrahedra. There are a spread of Cr–O bond distances ranging from 1.97–2.04 Å. There are four inequivalent P5+ sites. In the first P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two equivalent CrO5 square pyramids, a cornercorner with one PO4 tetrahedra, and a cornercorner with one CrO5 trigonal bipyramid. There are a spread of P–O bond distances ranging from 1.52–1.60 Å. In the second P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share a cornercorner with one CrO5 square pyramid, a cornercorner with one PO4 tetrahedra, and corners with two equivalent CrO5 trigonal bipyramids. There are a spread of P–O bond distances ranging from 1.52–1.62 Å. In the third P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share a cornercorner with one CrO5 square pyramid, a cornercorner with one PO4 tetrahedra, and a cornercorner with one CrO5 trigonal bipyramid. There are a spread of P–O bond distances ranging from 1.48–1.59 Å. In the fourth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share a cornercorner with one CrO5 square pyramid, a cornercorner with one PO4 tetrahedra, and a cornercorner with one CrO5 trigonal bipyramid. There are a spread of P–O bond distances ranging from 1.49–1.61 Å. There are fourteen inequivalent O2- sites. In the first O2- site, O2- is bonded in a 3-coordinate geometry to one Ca2+, one Cr3+, and one P5+ atom. In the second O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Cr3+ and one P5+ atom. In the third O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Ca2+, one Cr3+, and one P5+ atom. In the fourth O2- site, O2- is bonded in a bent 150 degrees geometry to one Cr3+ and one P5+ atom. In the fifth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Cr3+ and one P5+ atom. In the sixth O2- site, O2- is bonded in a 2-coordinate geometry to one Ca2+, one Cr3+, and one P5+ atom. In the seventh O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Ca2+ and one P5+ atom. In the eighth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Ca2+ and one P5+ atom. In the ninth O2- site, O2- is bonded in a 2-coordinate geometry to one Ca2+, one Cr3+, and one P5+ atom. In the tenth O2- site, O2- is bonded in a 2-coordinate geometry to one Ca2+, one Cr3+, and one P5+ atom. In the eleventh O2- site, O2- is bonded in a bent 150 degrees geometry to two P5+ atoms. In the twelfth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Cr3+ and one P5+ atom. In the thirteenth O2- site, O2- is bonded in a 3-coordinate geometry to one Ca2+, one Cr3+, and one P5+ atom. In the fourteenth O2- site, O2- is bonded in a bent 150 degrees geometry to two P5+ atoms.