Ca4ZrTi3(SiO5)4 crystallizes in the triclinic P-1 space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 7-coordinate geometry to one O(10), one O(2), one O(3), one O(6), one O(9), and two equivalent O(7) atoms. In the second Ca site, Ca(2) is bonded in a 7-coordinate geometry to one O(1), one O(10), one O(4), one O(5), one O(9), and two equivalent O(8) atoms. Zr(1) is bonded to two equivalent O(3), two equivalent O(6), and two equivalent O(7) atoms to form ZrO6 octahedra that share corners with two equivalent Ti(2)O6 octahedra and corners with four equivalent Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles are 41°. There are two inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to two equivalent O(4), two equivalent O(5), and two equivalent O(8) atoms to form TiO6 octahedra that share corners with two equivalent Ti(2)O6 octahedra and corners with four equivalent Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 39°. In the second Ti site, Ti(2) is bonded to one O(1), one O(10), one O(2), one O(5), one O(6), and one O(9) atom to form TiO6 octahedra that share  a cornercorner with one Zr(1)O6 octahedra,  a cornercorner with one Ti(1)O6 octahedra, corners with two equivalent Si(1)O4 tetrahedra, and corners with two equivalent Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 39-41°. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(4), one O(8), and one O(9) atom to form SiO4 tetrahedra that share corners with two equivalent Ti(1)O6 octahedra and corners with two equivalent Ti(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 37-52°. In the second Si site, Si(2) is bonded to one O(10), one O(2), one O(3), and one O(7) atom to form SiO4 tetrahedra that share corners with two equivalent Zr(1)O6 octahedra and corners with two equivalent Ti(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 38-54°. There are ten inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Ca(2), one Ti(2), and one Si(1) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Ca(1), one Ti(2), and one Si(2) atom. In the third O site, O(3) is bonded in a distorted T-shaped geometry to one Ca(1), one Zr(1), and one Si(2) atom. In the fourth O site, O(4) is bonded in a distorted T-shaped geometry to one Ca(2), one Ti(1), and one Si(1) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Ca(2), one Ti(1), and one Ti(2) atom. In the sixth O site, O(6) is bonded in a distorted trigonal planar geometry to one Ca(1), one Zr(1), and one Ti(2) atom. In the seventh O site, O(7) is bonded in a 4-coordinate geometry to two equivalent Ca(1), one Zr(1), and one Si(2) atom. In the eighth O site, O(8) is bonded in a 4-coordinate geometry to two equivalent Ca(2), one Ti(1), and one Si(1) atom. In the ninth O site, O(9) is bonded in a 4-coordinate geometry to one Ca(1), one Ca(2), one Ti(2), and one Si(1) atom. In the tenth O site, O(10) is bonded in a 4-coordinate geometry to one Ca(1), one Ca(2), one Ti(2), and one Si(2) atom.
Ca4ZrTi3(SiO5)4 crystallizes in the triclinic P-1 space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 7-coordinate geometry to one O(10), one O(2), one O(3), one O(6), one O(9), and two equivalent O(7) atoms. The Ca(1)-O(10) bond length is 2.46 Å. The Ca(1)-O(2) bond length is 2.41 Å. The Ca(1)-O(3) bond length is 2.44 Å. The Ca(1)-O(6) bond length is 2.25 Å. The Ca(1)-O(9) bond length is 2.64 Å. There is one shorter (2.48 Å) and one longer (2.79 Å) Ca(1)-O(7) bond length. In the second Ca site, Ca(2) is bonded in a 7-coordinate geometry to one O(1), one O(10), one O(4), one O(5), one O(9), and two equivalent O(8) atoms. The Ca(2)-O(1) bond length is 2.47 Å. The Ca(2)-O(10) bond length is 2.68 Å. The Ca(2)-O(4) bond length is 2.44 Å. The Ca(2)-O(5) bond length is 2.28 Å. The Ca(2)-O(9) bond length is 2.47 Å. There is one shorter (2.49 Å) and one longer (2.64 Å) Ca(2)-O(8) bond length. Zr(1) is bonded to two equivalent O(3), two equivalent O(6), and two equivalent O(7) atoms to form ZrO6 octahedra that share corners with two equivalent Ti(2)O6 octahedra and corners with four equivalent Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles are 41°. Both Zr(1)-O(3) bond lengths are 2.11 Å. Both Zr(1)-O(6) bond lengths are 2.04 Å. Both Zr(1)-O(7) bond lengths are 2.14 Å. There are two inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to two equivalent O(4), two equivalent O(5), and two equivalent O(8) atoms to form TiO6 octahedra that share corners with two equivalent Ti(2)O6 octahedra and corners with four equivalent Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 39°. Both Ti(1)-O(4) bond lengths are 2.02 Å. Both Ti(1)-O(5) bond lengths are 1.89 Å. Both Ti(1)-O(8) bond lengths are 2.05 Å. In the second Ti site, Ti(2) is bonded to one O(1), one O(10), one O(2), one O(5), one O(6), and one O(9) atom to form TiO6 octahedra that share  a cornercorner with one Zr(1)O6 octahedra,  a cornercorner with one Ti(1)O6 octahedra, corners with two equivalent Si(1)O4 tetrahedra, and corners with two equivalent Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 39-41°. The Ti(2)-O(1) bond length is 2.00 Å. The Ti(2)-O(10) bond length is 2.07 Å. The Ti(2)-O(2) bond length is 2.01 Å. The Ti(2)-O(5) bond length is 1.90 Å. The Ti(2)-O(6) bond length is 1.86 Å. The Ti(2)-O(9) bond length is 2.05 Å. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(4), one O(8), and one O(9) atom to form SiO4 tetrahedra that share corners with two equivalent Ti(1)O6 octahedra and corners with two equivalent Ti(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 37-52°. The Si(1)-O(1) bond length is 1.65 Å. The Si(1)-O(4) bond length is 1.65 Å. The Si(1)-O(8) bond length is 1.66 Å. The Si(1)-O(9) bond length is 1.65 Å. In the second Si site, Si(2) is bonded to one O(10), one O(2), one O(3), and one O(7) atom to form SiO4 tetrahedra that share corners with two equivalent Zr(1)O6 octahedra and corners with two equivalent Ti(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 38-54°. The Si(2)-O(10) bond length is 1.66 Å. The Si(2)-O(2) bond length is 1.65 Å. The Si(2)-O(3) bond length is 1.64 Å. The Si(2)-O(7) bond length is 1.65 Å. There are ten inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Ca(2), one Ti(2), and one Si(1) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Ca(1), one Ti(2), and one Si(2) atom. In the third O site, O(3) is bonded in a distorted T-shaped geometry to one Ca(1), one Zr(1), and one Si(2) atom. In the fourth O site, O(4) is bonded in a distorted T-shaped geometry to one Ca(2), one Ti(1), and one Si(1) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Ca(2), one Ti(1), and one Ti(2) atom. In the sixth O site, O(6) is bonded in a distorted trigonal planar geometry to one Ca(1), one Zr(1), and one Ti(2) atom. In the seventh O site, O(7) is bonded in a 4-coordinate geometry to two equivalent Ca(1), one Zr(1), and one Si(2) atom. In the eighth O site, O(8) is bonded in a 4-coordinate geometry to two equivalent Ca(2), one Ti(1), and one Si(1) atom. In the ninth O site, O(9) is bonded in a 4-coordinate geometry to one Ca(1), one Ca(2), one Ti(2), and one Si(1) atom. In the tenth O site, O(10) is bonded in a 4-coordinate geometry to one Ca(1), one Ca(2), one Ti(2), and one Si(2) atom.