Ca3SiO5 crystallizes in the hexagonal P6_3mc space group. Ca(1) is bonded to one O(3), two equivalent O(2), and three equivalent O(1) atoms to form distorted CaO6 octahedra that share corners with four equivalent Ca(1)O6 octahedra, corners with four equivalent Si(1)O4 tetrahedra, edges with four equivalent Ca(1)O6 octahedra, and faces with two equivalent Ca(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 2-73°. Si(1) is bonded to one O(3) and three equivalent O(1) atoms to form SiO4 tetrahedra that share corners with twelve equivalent Ca(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 52-68°. There are three inequivalent O sites. In the first O site, O(1) is bonded in a distorted rectangular see-saw-like geometry to three equivalent Ca(1) and one Si(1) atom. In the second O site, O(2) is bonded to six equivalent Ca(1) atoms to form OCa6 octahedra that share corners with six equivalent O(3)Ca3Si tetrahedra and faces with two equivalent O(2)Ca6 octahedra. In the third O site, O(3) is bonded to three equivalent Ca(1) and one Si(1) atom to form corner-sharing OCa3Si tetrahedra. The corner-sharing octahedral tilt angles range from 13-59°.
Ca3SiO5 crystallizes in the hexagonal P6_3mc space group. Ca(1) is bonded to one O(3), two equivalent O(2), and three equivalent O(1) atoms to form distorted CaO6 octahedra that share corners with four equivalent Ca(1)O6 octahedra, corners with four equivalent Si(1)O4 tetrahedra, edges with four equivalent Ca(1)O6 octahedra, and faces with two equivalent Ca(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 2-73°. The Ca(1)-O(3) bond length is 2.47 Å. There is one shorter (2.32 Å) and one longer (2.38 Å) Ca(1)-O(2) bond length. There are two shorter (2.38 Å) and one longer (2.50 Å) Ca(1)-O(1) bond length. Si(1) is bonded to one O(3) and three equivalent O(1) atoms to form SiO4 tetrahedra that share corners with twelve equivalent Ca(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 52-68°. The Si(1)-O(3) bond length is 1.67 Å. All Si(1)-O(1) bond lengths are 1.65 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded in a distorted rectangular see-saw-like geometry to three equivalent Ca(1) and one Si(1) atom. In the second O site, O(2) is bonded to six equivalent Ca(1) atoms to form OCa6 octahedra that share corners with six equivalent O(3)Ca3Si tetrahedra and faces with two equivalent O(2)Ca6 octahedra. In the third O site, O(3) is bonded to three equivalent Ca(1) and one Si(1) atom to form corner-sharing OCa3Si tetrahedra. The corner-sharing octahedral tilt angles range from 13-59°.