Ti2Si2O5 crystallizes in the tetragonal P4/mmm space group. There are two inequivalent Ti sites. In the first Ti site, Ti(1) is bonded in a body-centered cubic geometry to eight equivalent O(1) atoms. In the second Ti site, Ti(2) is bonded to four equivalent O(2) and eight equivalent O(1) atoms to form TiO12 cuboctahedra that share corners with four equivalent Ti(2)O12 cuboctahedra, faces with four equivalent Ti(2)O12 cuboctahedra, and faces with eight equivalent Si(1)O5 square pyramids. Si(1) is bonded to one O(2) and four equivalent O(1) atoms to form SiO5 square pyramids that share corners with five equivalent Si(1)O5 square pyramids and faces with four equivalent Ti(2)O12 cuboctahedra. There are two inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Ti(1), two equivalent Ti(2), and two equivalent Si(1) atoms to form a mixture of distorted edge, face, and corner-sharing OTi4Si2 octahedra. The corner-sharing octahedral tilt angles range from 0-71°. In the second O site, O(2) is bonded in a linear geometry to four equivalent Ti(2) and two equivalent Si(1) atoms.
Ti2Si2O5 crystallizes in the tetragonal P4/mmm space group. There are two inequivalent Ti sites. In the first Ti site, Ti(1) is bonded in a body-centered cubic geometry to eight equivalent O(1) atoms. All Ti(1)-O(1) bond lengths are 2.31 Å. In the second Ti site, Ti(2) is bonded to four equivalent O(2) and eight equivalent O(1) atoms to form TiO12 cuboctahedra that share corners with four equivalent Ti(2)O12 cuboctahedra, faces with four equivalent Ti(2)O12 cuboctahedra, and faces with eight equivalent Si(1)O5 square pyramids. All Ti(2)-O(2) bond lengths are 2.68 Å. All Ti(2)-O(1) bond lengths are 2.47 Å. Si(1) is bonded to one O(2) and four equivalent O(1) atoms to form SiO5 square pyramids that share corners with five equivalent Si(1)O5 square pyramids and faces with four equivalent Ti(2)O12 cuboctahedra. The Si(1)-O(2) bond length is 1.69 Å. All Si(1)-O(1) bond lengths are 1.90 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Ti(1), two equivalent Ti(2), and two equivalent Si(1) atoms to form a mixture of distorted edge, face, and corner-sharing OTi4Si2 octahedra. The corner-sharing octahedral tilt angles range from 0-71°. In the second O site, O(2) is bonded in a linear geometry to four equivalent Ti(2) and two equivalent Si(1) atoms.