Ca3Cr3(PO4)4 crystallizes in the triclinic P-1 space group. There are three inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 8-coordinate geometry to one O(10), one O(2), one O(3), one O(4), one O(5), one O(9), and two equivalent O(7) atoms. In the second Ca site, Ca(2) is bonded in a 7-coordinate geometry to one O(13), one O(15), one O(16), one O(2), one O(8), and two equivalent O(1) atoms. In the third Ca site, Ca(3) is bonded in a 7-coordinate geometry to one O(11), one O(12), one O(13), one O(14), one O(16), one O(3), and one O(5) atom. There are three inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to one O(10), one O(14), one O(15), one O(5), and one O(6) atom to form distorted CrO5 trigonal bipyramids that share  a cornercorner with one P(2)O4 tetrahedra, corners with two equivalent P(1)O4 tetrahedra, and corners with two equivalent P(4)O4 tetrahedra. In the second Cr site, Cr(2) is bonded in a rectangular see-saw-like geometry to one O(13), one O(4), one O(8), and one O(9) atom. In the third Cr site, Cr(3) is bonded in a rectangular see-saw-like geometry to one O(10), one O(11), one O(12), and one O(4) atom. There are four inequivalent P sites. In the first P site, P(1) is bonded to one O(10), one O(11), one O(15), and one O(3) atom to form PO4 tetrahedra that share corners with two equivalent Cr(1)O5 trigonal bipyramids. In the second P site, P(2) is bonded to one O(1), one O(13), one O(14), and one O(9) atom to form PO4 tetrahedra that share  a cornercorner with one Cr(1)O5 trigonal bipyramid. In the third P site, P(3) is bonded in a tetrahedral geometry to one O(12), one O(4), one O(7), and one O(8) atom. In the fourth P site, P(4) is bonded to one O(16), one O(2), one O(5), and one O(6) atom to form PO4 tetrahedra that share corners with two equivalent Cr(1)O5 trigonal bipyramids. There are sixteen inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to two equivalent Ca(2) and one P(2) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Ca(1), one Ca(2), and one P(4) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Ca(1), one Ca(3), and one P(1) atom. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one Ca(1), one Cr(2), one Cr(3), and one P(3) atom. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to one Ca(1), one Ca(3), one Cr(1), and one P(4) atom. In the sixth O site, O(6) is bonded in a distorted water-like geometry to one Cr(1) and one P(4) atom. In the seventh O site, O(7) is bonded in a 3-coordinate geometry to two equivalent Ca(1) and one P(3) atom. In the eighth O site, O(8) is bonded in a distorted trigonal planar geometry to one Ca(2), one Cr(2), and one P(3) atom. In the ninth O site, O(9) is bonded in a distorted trigonal planar geometry to one Ca(1), one Cr(2), and one P(2) atom. In the tenth O site, O(10) is bonded in a 4-coordinate geometry to one Ca(1), one Cr(1), one Cr(3), and one P(1) atom. In the eleventh O site, O(11) is bonded in a 3-coordinate geometry to one Ca(3), one Cr(3), and one P(1) atom. In the twelfth O site, O(12) is bonded in a 3-coordinate geometry to one Ca(3), one Cr(3), and one P(3) atom. In the thirteenth O site, O(13) is bonded in a 4-coordinate geometry to one Ca(2), one Ca(3), one Cr(2), and one P(2) atom. In the fourteenth O site, O(14) is bonded in a 3-coordinate geometry to one Ca(3), one Cr(1), and one P(2) atom. In the fifteenth O site, O(15) is bonded in a trigonal planar geometry to one Ca(2), one Cr(1), and one P(1) atom. In the sixteenth O site, O(16) is bonded in a 3-coordinate geometry to one Ca(2), one Ca(3), and one P(4) atom.
Ca3Cr3(PO4)4 crystallizes in the triclinic P-1 space group. There are three inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 8-coordinate geometry to one O(10), one O(2), one O(3), one O(4), one O(5), one O(9), and two equivalent O(7) atoms. The Ca(1)-O(10) bond length is 2.58 Å. The Ca(1)-O(2) bond length is 2.49 Å. The Ca(1)-O(3) bond length is 2.63 Å. The Ca(1)-O(4) bond length is 2.90 Å. The Ca(1)-O(5) bond length is 2.71 Å. The Ca(1)-O(9) bond length is 2.49 Å. There is one shorter (2.32 Å) and one longer (2.50 Å) Ca(1)-O(7) bond length. In the second Ca site, Ca(2) is bonded in a 7-coordinate geometry to one O(13), one O(15), one O(16), one O(2), one O(8), and two equivalent O(1) atoms. The Ca(2)-O(13) bond length is 2.79 Å. The Ca(2)-O(15) bond length is 2.34 Å. The Ca(2)-O(16) bond length is 2.48 Å. The Ca(2)-O(2) bond length is 2.39 Å. The Ca(2)-O(8) bond length is 2.36 Å. There is one shorter (2.32 Å) and one longer (2.59 Å) Ca(2)-O(1) bond length. In the third Ca site, Ca(3) is bonded in a 7-coordinate geometry to one O(11), one O(12), one O(13), one O(14), one O(16), one O(3), and one O(5) atom. The Ca(3)-O(11) bond length is 2.39 Å. The Ca(3)-O(12) bond length is 2.52 Å. The Ca(3)-O(13) bond length is 2.45 Å. The Ca(3)-O(14) bond length is 2.49 Å. The Ca(3)-O(16) bond length is 2.45 Å. The Ca(3)-O(3) bond length is 2.41 Å. The Ca(3)-O(5) bond length is 2.57 Å. There are three inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to one O(10), one O(14), one O(15), one O(5), and one O(6) atom to form distorted CrO5 trigonal bipyramids that share  a cornercorner with one P(2)O4 tetrahedra, corners with two equivalent P(1)O4 tetrahedra, and corners with two equivalent P(4)O4 tetrahedra. The Cr(1)-O(10) bond length is 2.53 Å. The Cr(1)-O(14) bond length is 2.13 Å. The Cr(1)-O(15) bond length is 2.10 Å. The Cr(1)-O(5) bond length is 2.06 Å. The Cr(1)-O(6) bond length is 2.10 Å. In the second Cr site, Cr(2) is bonded in a rectangular see-saw-like geometry to one O(13), one O(4), one O(8), and one O(9) atom. The Cr(2)-O(13) bond length is 2.08 Å. The Cr(2)-O(4) bond length is 2.07 Å. The Cr(2)-O(8) bond length is 2.06 Å. The Cr(2)-O(9) bond length is 2.05 Å. In the third Cr site, Cr(3) is bonded in a rectangular see-saw-like geometry to one O(10), one O(11), one O(12), and one O(4) atom. The Cr(3)-O(10) bond length is 2.05 Å. The Cr(3)-O(11) bond length is 2.03 Å. The Cr(3)-O(12) bond length is 2.06 Å. The Cr(3)-O(4) bond length is 2.03 Å. There are four inequivalent P sites. In the first P site, P(1) is bonded to one O(10), one O(11), one O(15), and one O(3) atom to form PO4 tetrahedra that share corners with two equivalent Cr(1)O5 trigonal bipyramids. The P(1)-O(10) bond length is 1.57 Å. The P(1)-O(11) bond length is 1.56 Å. The P(1)-O(15) bond length is 1.55 Å. The P(1)-O(3) bond length is 1.54 Å. In the second P site, P(2) is bonded to one O(1), one O(13), one O(14), and one O(9) atom to form PO4 tetrahedra that share  a cornercorner with one Cr(1)O5 trigonal bipyramid. The P(2)-O(1) bond length is 1.52 Å. The P(2)-O(13) bond length is 1.58 Å. The P(2)-O(14) bond length is 1.57 Å. The P(2)-O(9) bond length is 1.56 Å. In the third P site, P(3) is bonded in a tetrahedral geometry to one O(12), one O(4), one O(7), and one O(8) atom. The P(3)-O(12) bond length is 1.55 Å. The P(3)-O(4) bond length is 1.58 Å. The P(3)-O(7) bond length is 1.52 Å. The P(3)-O(8) bond length is 1.55 Å. In the fourth P site, P(4) is bonded to one O(16), one O(2), one O(5), and one O(6) atom to form PO4 tetrahedra that share corners with two equivalent Cr(1)O5 trigonal bipyramids. The P(4)-O(16) bond length is 1.55 Å. The P(4)-O(2) bond length is 1.55 Å. The P(4)-O(5) bond length is 1.58 Å. The P(4)-O(6) bond length is 1.56 Å. There are sixteen inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to two equivalent Ca(2) and one P(2) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Ca(1), one Ca(2), and one P(4) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Ca(1), one Ca(3), and one P(1) atom. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one Ca(1), one Cr(2), one Cr(3), and one P(3) atom. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to one Ca(1), one Ca(3), one Cr(1), and one P(4) atom. In the sixth O site, O(6) is bonded in a distorted water-like geometry to one Cr(1) and one P(4) atom. In the seventh O site, O(7) is bonded in a 3-coordinate geometry to two equivalent Ca(1) and one P(3) atom. In the eighth O site, O(8) is bonded in a distorted trigonal planar geometry to one Ca(2), one Cr(2), and one P(3) atom. In the ninth O site, O(9) is bonded in a distorted trigonal planar geometry to one Ca(1), one Cr(2), and one P(2) atom. In the tenth O site, O(10) is bonded in a 4-coordinate geometry to one Ca(1), one Cr(1), one Cr(3), and one P(1) atom. In the eleventh O site, O(11) is bonded in a 3-coordinate geometry to one Ca(3), one Cr(3), and one P(1) atom. In the twelfth O site, O(12) is bonded in a 3-coordinate geometry to one Ca(3), one Cr(3), and one P(3) atom. In the thirteenth O site, O(13) is bonded in a 4-coordinate geometry to one Ca(2), one Ca(3), one Cr(2), and one P(2) atom. In the fourteenth O site, O(14) is bonded in a 3-coordinate geometry to one Ca(3), one Cr(1), and one P(2) atom. In the fifteenth O site, O(15) is bonded in a trigonal planar geometry to one Ca(2), one Cr(1), and one P(1) atom. In the sixteenth O site, O(16) is bonded in a 3-coordinate geometry to one Ca(2), one Ca(3), and one P(4) atom.