Ca2SiO4 crystallizes in the monoclinic P2_1/c space group. There are three inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 5-coordinate geometry to one O(1), one O(2), one O(4), and two equivalent O(3) atoms. In the second Ca site, Ca(2) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(4) atoms to form CaO6 octahedra that share corners with six equivalent Si(1)O4 tetrahedra and edges with two equivalent Ca(3)O6 octahedra. In the third Ca site, Ca(3) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms to form CaO6 octahedra that share corners with six equivalent Si(1)O4 tetrahedra and edges with two equivalent Ca(2)O6 octahedra. Si(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form SiO4 tetrahedra that share corners with three equivalent Ca(2)O6 octahedra and corners with three equivalent Ca(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 30-62°. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Ca(1), one Ca(2), one Ca(3), and one Si(1) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Ca(1), one Ca(2), and one Si(1) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Ca(3), two equivalent Ca(1), and one Si(1) atom. In the fourth O site, O(4) is bonded to one Ca(1), one Ca(2), one Ca(3), and one Si(1) atom to form distorted corner-sharing OCa3Si tetrahedra.
Ca2SiO4 crystallizes in the monoclinic P2_1/c space group. There are three inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 5-coordinate geometry to one O(1), one O(2), one O(4), and two equivalent O(3) atoms. The Ca(1)-O(1) bond length is 2.43 Å. The Ca(1)-O(2) bond length is 2.25 Å. The Ca(1)-O(4) bond length is 2.36 Å. There is one shorter (2.43 Å) and one longer (2.67 Å) Ca(1)-O(3) bond length. In the second Ca site, Ca(2) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(4) atoms to form CaO6 octahedra that share corners with six equivalent Si(1)O4 tetrahedra and edges with two equivalent Ca(3)O6 octahedra. Both Ca(2)-O(1) bond lengths are 2.49 Å. Both Ca(2)-O(2) bond lengths are 2.42 Å. Both Ca(2)-O(4) bond lengths are 2.41 Å. In the third Ca site, Ca(3) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms to form CaO6 octahedra that share corners with six equivalent Si(1)O4 tetrahedra and edges with two equivalent Ca(2)O6 octahedra. Both Ca(3)-O(1) bond lengths are 2.30 Å. Both Ca(3)-O(3) bond lengths are 2.25 Å. Both Ca(3)-O(4) bond lengths are 2.46 Å. Si(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form SiO4 tetrahedra that share corners with three equivalent Ca(2)O6 octahedra and corners with three equivalent Ca(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 30-62°. The Si(1)-O(1) bond length is 1.67 Å. The Si(1)-O(2) bond length is 1.63 Å. The Si(1)-O(3) bond length is 1.65 Å. The Si(1)-O(4) bond length is 1.67 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Ca(1), one Ca(2), one Ca(3), and one Si(1) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Ca(1), one Ca(2), and one Si(1) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Ca(3), two equivalent Ca(1), and one Si(1) atom. In the fourth O site, O(4) is bonded to one Ca(1), one Ca(2), one Ca(3), and one Si(1) atom to form distorted corner-sharing OCa3Si tetrahedra.