Ca10(PO4)6Se crystallizes in the trigonal P-3 space group. There are three inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 7-coordinate geometry to one Se(1), one O(1), one O(2), two equivalent O(3), and two equivalent O(4) atoms. In the second Ca site, Ca(2) is bonded in a 9-coordinate geometry to three equivalent O(1), three equivalent O(2), and three equivalent O(4) atoms. In the third Ca site, Ca(3) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form distorted CaO6 pentagonal pyramids that share corners with six equivalent P(1)O4 tetrahedra. P(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form PO4 tetrahedra that share corners with two equivalent Ca(3)O6 pentagonal pyramids. Se(1) is bonded in an octahedral geometry to six equivalent Ca(1) atoms. There are four inequivalent O sites. In the first O site, O(4) is bonded in a 4-coordinate geometry to one Ca(2), two equivalent Ca(1), and one P(1) atom. In the second O site, O(1) is bonded in a 4-coordinate geometry to one Ca(1), one Ca(2), one Ca(3), and one P(1) atom. In the third O site, O(2) is bonded in a 4-coordinate geometry to one Ca(1), one Ca(2), one Ca(3), and one P(1) atom. In the fourth O site, O(3) is bonded in a 3-coordinate geometry to two equivalent Ca(1) and one P(1) atom.
Ca10(PO4)6Se crystallizes in the trigonal P-3 space group. There are three inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 7-coordinate geometry to one Se(1), one O(1), one O(2), two equivalent O(3), and two equivalent O(4) atoms. The Ca(1)-Se(1) bond length is 3.01 Å. The Ca(1)-O(1) bond length is 2.69 Å. The Ca(1)-O(2) bond length is 2.38 Å. There is one shorter (2.40 Å) and one longer (2.45 Å) Ca(1)-O(3) bond length. There is one shorter (2.35 Å) and one longer (2.86 Å) Ca(1)-O(4) bond length. In the second Ca site, Ca(2) is bonded in a 9-coordinate geometry to three equivalent O(1), three equivalent O(2), and three equivalent O(4) atoms. All Ca(2)-O(1) bond lengths are 2.47 Å. All Ca(2)-O(2) bond lengths are 2.72 Å. All Ca(2)-O(4) bond lengths are 2.50 Å. In the third Ca site, Ca(3) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form distorted CaO6 pentagonal pyramids that share corners with six equivalent P(1)O4 tetrahedra. All Ca(3)-O(1) bond lengths are 2.37 Å. All Ca(3)-O(2) bond lengths are 2.36 Å. P(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form PO4 tetrahedra that share corners with two equivalent Ca(3)O6 pentagonal pyramids. The P(1)-O(1) bond length is 1.55 Å. The P(1)-O(2) bond length is 1.56 Å. The P(1)-O(3) bond length is 1.56 Å. The P(1)-O(4) bond length is 1.55 Å. Se(1) is bonded in an octahedral geometry to six equivalent Ca(1) atoms. There are four inequivalent O sites. In the first O site, O(4) is bonded in a 4-coordinate geometry to one Ca(2), two equivalent Ca(1), and one P(1) atom. In the second O site, O(1) is bonded in a 4-coordinate geometry to one Ca(1), one Ca(2), one Ca(3), and one P(1) atom. In the third O site, O(2) is bonded in a 4-coordinate geometry to one Ca(1), one Ca(2), one Ca(3), and one P(1) atom. In the fourth O site, O(3) is bonded in a 3-coordinate geometry to two equivalent Ca(1) and one P(1) atom.