Sr2Ge2O5 crystallizes in the tetragonal P4/mmm space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a body-centered cubic geometry to eight equivalent O(1) atoms. In the second Sr site, Sr(2) is bonded to four equivalent O(2) and eight equivalent O(1) atoms to form SrO12 cuboctahedra that share corners with four equivalent Sr(2)O12 cuboctahedra, faces with four equivalent Sr(2)O12 cuboctahedra, and faces with eight equivalent Ge(1)O5 square pyramids. Ge(1) is bonded to one O(2) and four equivalent O(1) atoms to form GeO5 square pyramids that share corners with five equivalent Ge(1)O5 square pyramids and faces with four equivalent Sr(2)O12 cuboctahedra. There are two inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Sr(1), two equivalent Sr(2), and two equivalent Ge(1) atoms to form a mixture of distorted edge, corner, and face-sharing OSr4Ge2 octahedra. The corner-sharing octahedral tilt angles range from 0-65°. In the second O site, O(2) is bonded in a distorted linear geometry to four equivalent Sr(2) and two equivalent Ge(1) atoms.
Sr2Ge2O5 crystallizes in the tetragonal P4/mmm space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a body-centered cubic geometry to eight equivalent O(1) atoms. All Sr(1)-O(1) bond lengths are 2.64 Å. In the second Sr site, Sr(2) is bonded to four equivalent O(2) and eight equivalent O(1) atoms to form SrO12 cuboctahedra that share corners with four equivalent Sr(2)O12 cuboctahedra, faces with four equivalent Sr(2)O12 cuboctahedra, and faces with eight equivalent Ge(1)O5 square pyramids. All Sr(2)-O(2) bond lengths are 2.85 Å. All Sr(2)-O(1) bond lengths are 2.81 Å. Ge(1) is bonded to one O(2) and four equivalent O(1) atoms to form GeO5 square pyramids that share corners with five equivalent Ge(1)O5 square pyramids and faces with four equivalent Sr(2)O12 cuboctahedra. The Ge(1)-O(2) bond length is 1.89 Å. All Ge(1)-O(1) bond lengths are 2.02 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Sr(1), two equivalent Sr(2), and two equivalent Ge(1) atoms to form a mixture of distorted edge, corner, and face-sharing OSr4Ge2 octahedra. The corner-sharing octahedral tilt angles range from 0-65°. In the second O site, O(2) is bonded in a distorted linear geometry to four equivalent Sr(2) and two equivalent Ge(1) atoms.