Ca2SiO4 is (La,Ba)CuO4 structured and crystallizes in the tetragonal I4/mmm space group. Ca(1) is bonded in a 9-coordinate geometry to four equivalent O(1) and five equivalent O(2) atoms. Si(1) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form corner-sharing SiO6 octahedra. The corner-sharing octahedra are not tilted. There are two inequivalent O sites. In the first O site, O(2) is bonded to five equivalent Ca(1) and one Si(1) atom to form distorted OCa5Si octahedra that share corners with five equivalent O(2)Ca5Si octahedra, corners with twelve equivalent O(1)Ca4Si2 octahedra, edges with eight equivalent O(2)Ca5Si octahedra, and faces with four equivalent O(1)Ca4Si2 octahedra. The corner-sharing octahedral tilt angles range from 0-57°. In the second O site, O(1) is bonded to four equivalent Ca(1) and two equivalent Si(1) atoms to form distorted OCa4Si2 octahedra that share corners with two equivalent O(1)Ca4Si2 octahedra, corners with twelve equivalent O(2)Ca5Si octahedra, edges with two equivalent O(1)Ca4Si2 octahedra, faces with four equivalent O(1)Ca4Si2 octahedra, and faces with four equivalent O(2)Ca5Si octahedra. The corner-sharing octahedral tilt angles range from 0-57°.
Ca2SiO4 is (La,Ba)CuO4 structured and crystallizes in the tetragonal I4/mmm space group. Ca(1) is bonded in a 9-coordinate geometry to four equivalent O(1) and five equivalent O(2) atoms. All Ca(1)-O(1) bond lengths are 2.49 Å. There is one shorter (2.33 Å) and four longer (2.56 Å) Ca(1)-O(2) bond lengths. Si(1) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form corner-sharing SiO6 octahedra. The corner-sharing octahedra are not tilted. Both Si(1)-O(2) bond lengths are 1.82 Å. All Si(1)-O(1) bond lengths are 1.81 Å. There are two inequivalent O sites. In the first O site, O(2) is bonded to five equivalent Ca(1) and one Si(1) atom to form distorted OCa5Si octahedra that share corners with five equivalent O(2)Ca5Si octahedra, corners with twelve equivalent O(1)Ca4Si2 octahedra, edges with eight equivalent O(2)Ca5Si octahedra, and faces with four equivalent O(1)Ca4Si2 octahedra. The corner-sharing octahedral tilt angles range from 0-57°. In the second O site, O(1) is bonded to four equivalent Ca(1) and two equivalent Si(1) atoms to form distorted OCa4Si2 octahedra that share corners with two equivalent O(1)Ca4Si2 octahedra, corners with twelve equivalent O(2)Ca5Si octahedra, edges with two equivalent O(1)Ca4Si2 octahedra, faces with four equivalent O(1)Ca4Si2 octahedra, and faces with four equivalent O(2)Ca5Si octahedra. The corner-sharing octahedral tilt angles range from 0-57°.