Ba3CaTi3O8 crystallizes in the triclinic P1 space group. There are three inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 5-coordinate geometry to one O(2), one O(3), one O(4), one O(5), one O(6), and two equivalent O(1) atoms. In the second Ba site, Ba(2) is bonded in a 5-coordinate geometry to one O(1), one O(2), one O(4), one O(7), one O(8), and two equivalent O(5) atoms. In the third Ba site, Ba(3) is bonded in a distorted q6 geometry to one O(1), one O(3), one O(5), one O(6), one O(7), one O(8), two equivalent O(2), and two equivalent O(4) atoms. Ca(1) is bonded in a square co-planar geometry to one O(3), one O(6), one O(7), and one O(8) atom. There are three inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to one O(2), one O(4), one O(5), one O(7), and one O(8) atom to form TiO5 square pyramids that share corners with three equivalent Ti(3)O6 octahedra and corners with two equivalent Ti(2)O5 square pyramids. The corner-sharing octahedral tilt angles range from 4-9°. In the second Ti site, Ti(2) is bonded to one O(1), one O(2), one O(3), one O(4), and one O(6) atom to form TiO5 square pyramids that share corners with three equivalent Ti(3)O6 octahedra and corners with two equivalent Ti(1)O5 square pyramids. The corner-sharing octahedral tilt angles range from 4-9°. In the third Ti site, Ti(3) is bonded to one O(1), one O(3), one O(5), one O(6), one O(7), and one O(8) atom to form corner-sharing TiO6 octahedra. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a 6-coordinate geometry to one Ba(2), one Ba(3), two equivalent Ba(1), one Ti(2), and one Ti(3) atom. In the second O site, O(2) is bonded in a 6-coordinate geometry to one Ba(1), one Ba(2), two equivalent Ba(3), one Ti(1), and one Ti(2) atom. In the third O site, O(3) is bonded in a 5-coordinate geometry to one Ba(1), one Ba(3), one Ca(1), one Ti(2), and one Ti(3) atom. In the fourth O site, O(4) is bonded to one Ba(1), one Ba(2), two equivalent Ba(3), one Ti(1), and one Ti(2) atom to form distorted corner-sharing OBa4Ti2 octahedra. The corner-sharing octahedra are not tilted. In the fifth O site, O(5) is bonded in a 6-coordinate geometry to one Ba(1), one Ba(3), two equivalent Ba(2), one Ti(1), and one Ti(3) atom. In the sixth O site, O(6) is bonded in a 5-coordinate geometry to one Ba(1), one Ba(3), one Ca(1), one Ti(2), and one Ti(3) atom. In the seventh O site, O(7) is bonded in a 5-coordinate geometry to one Ba(2), one Ba(3), one Ca(1), one Ti(1), and one Ti(3) atom. In the eighth O site, O(8) is bonded in a 5-coordinate geometry to one Ba(2), one Ba(3), one Ca(1), one Ti(1), and one Ti(3) atom.
Ba3CaTi3O8 crystallizes in the triclinic P1 space group. There are three inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 5-coordinate geometry to one O(2), one O(3), one O(4), one O(5), one O(6), and two equivalent O(1) atoms. The Ba(1)-O(2) bond length is 2.65 Å. The Ba(1)-O(3) bond length is 2.61 Å. The Ba(1)-O(4) bond length is 2.91 Å. The Ba(1)-O(5) bond length is 3.18 Å. The Ba(1)-O(6) bond length is 2.66 Å. There is one shorter (2.85 Å) and one longer (3.19 Å) Ba(1)-O(1) bond length. In the second Ba site, Ba(2) is bonded in a 5-coordinate geometry to one O(1), one O(2), one O(4), one O(7), one O(8), and two equivalent O(5) atoms. The Ba(2)-O(1) bond length is 3.18 Å. The Ba(2)-O(2) bond length is 2.65 Å. The Ba(2)-O(4) bond length is 2.91 Å. The Ba(2)-O(7) bond length is 2.61 Å. The Ba(2)-O(8) bond length is 2.66 Å. There is one shorter (2.85 Å) and one longer (3.19 Å) Ba(2)-O(5) bond length. In the third Ba site, Ba(3) is bonded in a distorted q6 geometry to one O(1), one O(3), one O(5), one O(6), one O(7), one O(8), two equivalent O(2), and two equivalent O(4) atoms. The Ba(3)-O(1) bond length is 3.03 Å. The Ba(3)-O(3) bond length is 2.95 Å. The Ba(3)-O(5) bond length is 3.03 Å. The Ba(3)-O(6) bond length is 2.84 Å. The Ba(3)-O(7) bond length is 2.95 Å. The Ba(3)-O(8) bond length is 2.85 Å. Both Ba(3)-O(2) bond lengths are 3.03 Å. Both Ba(3)-O(4) bond lengths are 2.97 Å. Ca(1) is bonded in a square co-planar geometry to one O(3), one O(6), one O(7), and one O(8) atom. The Ca(1)-O(3) bond length is 2.18 Å. The Ca(1)-O(6) bond length is 2.18 Å. The Ca(1)-O(7) bond length is 2.18 Å. The Ca(1)-O(8) bond length is 2.18 Å. There are three inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to one O(2), one O(4), one O(5), one O(7), and one O(8) atom to form TiO5 square pyramids that share corners with three equivalent Ti(3)O6 octahedra and corners with two equivalent Ti(2)O5 square pyramids. The corner-sharing octahedral tilt angles range from 4-9°. The Ti(1)-O(2) bond length is 2.02 Å. The Ti(1)-O(4) bond length is 2.15 Å. The Ti(1)-O(5) bond length is 1.99 Å. The Ti(1)-O(7) bond length is 2.10 Å. The Ti(1)-O(8) bond length is 2.02 Å. In the second Ti site, Ti(2) is bonded to one O(1), one O(2), one O(3), one O(4), and one O(6) atom to form TiO5 square pyramids that share corners with three equivalent Ti(3)O6 octahedra and corners with two equivalent Ti(1)O5 square pyramids. The corner-sharing octahedral tilt angles range from 4-9°. The Ti(2)-O(1) bond length is 1.99 Å. The Ti(2)-O(2) bond length is 2.02 Å. The Ti(2)-O(3) bond length is 2.10 Å. The Ti(2)-O(4) bond length is 2.15 Å. The Ti(2)-O(6) bond length is 2.02 Å. In the third Ti site, Ti(3) is bonded to one O(1), one O(3), one O(5), one O(6), one O(7), and one O(8) atom to form corner-sharing TiO6 octahedra. The Ti(3)-O(1) bond length is 2.32 Å. The Ti(3)-O(3) bond length is 2.07 Å. The Ti(3)-O(5) bond length is 2.30 Å. The Ti(3)-O(6) bond length is 2.11 Å. The Ti(3)-O(7) bond length is 2.07 Å. The Ti(3)-O(8) bond length is 2.11 Å. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a 6-coordinate geometry to one Ba(2), one Ba(3), two equivalent Ba(1), one Ti(2), and one Ti(3) atom. In the second O site, O(2) is bonded in a 6-coordinate geometry to one Ba(1), one Ba(2), two equivalent Ba(3), one Ti(1), and one Ti(2) atom. In the third O site, O(3) is bonded in a 5-coordinate geometry to one Ba(1), one Ba(3), one Ca(1), one Ti(2), and one Ti(3) atom. In the fourth O site, O(4) is bonded to one Ba(1), one Ba(2), two equivalent Ba(3), one Ti(1), and one Ti(2) atom to form distorted corner-sharing OBa4Ti2 octahedra. The corner-sharing octahedra are not tilted. In the fifth O site, O(5) is bonded in a 6-coordinate geometry to one Ba(1), one Ba(3), two equivalent Ba(2), one Ti(1), and one Ti(3) atom. In the sixth O site, O(6) is bonded in a 5-coordinate geometry to one Ba(1), one Ba(3), one Ca(1), one Ti(2), and one Ti(3) atom. In the seventh O site, O(7) is bonded in a 5-coordinate geometry to one Ba(2), one Ba(3), one Ca(1), one Ti(1), and one Ti(3) atom. In the eighth O site, O(8) is bonded in a 5-coordinate geometry to one Ba(2), one Ba(3), one Ca(1), one Ti(1), and one Ti(3) atom.