Ba2SrTi3O9 is (Cubic) Perovskite-derived structured and crystallizes in the orthorhombic Cmm2 space group. Ba(1) is bonded to one O(2), three equivalent O(1), four equivalent O(3), and four equivalent O(4) atoms to form BaO12 cuboctahedra that share corners with five equivalent Sr(1)O12 cuboctahedra, corners with seven equivalent Ba(1)O12 cuboctahedra, faces with two equivalent Sr(1)O12 cuboctahedra, faces with four equivalent Ba(1)O12 cuboctahedra, faces with two equivalent Ti(2)O6 octahedra, and faces with six equivalent Ti(1)O6 octahedra. Sr(1) is bonded to two equivalent O(1), two equivalent O(2), and eight equivalent O(3) atoms to form SrO12 cuboctahedra that share corners with two equivalent Sr(1)O12 cuboctahedra, corners with ten equivalent Ba(1)O12 cuboctahedra, faces with two equivalent Sr(1)O12 cuboctahedra, faces with four equivalent Ba(1)O12 cuboctahedra, faces with four equivalent Ti(1)O6 octahedra, and faces with four equivalent Ti(2)O6 octahedra. There are two inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms to form TiO6 octahedra that share corners with two equivalent Ti(2)O6 octahedra, corners with four equivalent Ti(1)O6 octahedra, faces with two equivalent Sr(1)O12 cuboctahedra, and faces with six equivalent Ba(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 2-10°. In the second Ti site, Ti(2) is bonded to two equivalent O(2) and four equivalent O(3) atoms to form TiO6 octahedra that share corners with two equivalent Ti(2)O6 octahedra, corners with four equivalent Ti(1)O6 octahedra, faces with four equivalent Ba(1)O12 cuboctahedra, and faces with four equivalent Sr(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-10°. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 6-coordinate geometry to three equivalent Ba(1), one Sr(1), and two equivalent Ti(1) atoms. In the second O site, O(2) is bonded to two equivalent Ba(1), two equivalent Sr(1), and two equivalent Ti(2) atoms to form distorted OBa2Sr2Ti2 octahedra that share corners with four equivalent O(2)Ba2Sr2Ti2 octahedra and corners with eight equivalent O(4)Ba4Ti2 octahedra. The corner-sharing octahedral tilt angles range from 0-63°. In the third O site, O(3) is bonded in a distorted linear geometry to two equivalent Ba(1), two equivalent Sr(1), one Ti(1), and one Ti(2) atom. In the fourth O site, O(4) is bonded to four equivalent Ba(1) and two equivalent Ti(1) atoms to form distorted OBa4Ti2 octahedra that share corners with four equivalent O(2)Ba2Sr2Ti2 octahedra, corners with four equivalent O(4)Ba4Ti2 octahedra, edges with two equivalent O(4)Ba4Ti2 octahedra, and faces with two equivalent O(4)Ba4Ti2 octahedra. The corner-sharing octahedral tilt angles range from 58-63°.
Ba2SrTi3O9 is (Cubic) Perovskite-derived structured and crystallizes in the orthorhombic Cmm2 space group. Ba(1) is bonded to one O(2), three equivalent O(1), four equivalent O(3), and four equivalent O(4) atoms to form BaO12 cuboctahedra that share corners with five equivalent Sr(1)O12 cuboctahedra, corners with seven equivalent Ba(1)O12 cuboctahedra, faces with two equivalent Sr(1)O12 cuboctahedra, faces with four equivalent Ba(1)O12 cuboctahedra, faces with two equivalent Ti(2)O6 octahedra, and faces with six equivalent Ti(1)O6 octahedra. The Ba(1)-O(2) bond length is 2.83 Å. There are two shorter (2.83 Å) and one longer (2.88 Å) Ba(1)-O(1) bond length. There are two shorter (2.82 Å) and two longer (2.95 Å) Ba(1)-O(3) bond lengths. There are two shorter (2.81 Å) and two longer (2.91 Å) Ba(1)-O(4) bond lengths. Sr(1) is bonded to two equivalent O(1), two equivalent O(2), and eight equivalent O(3) atoms to form SrO12 cuboctahedra that share corners with two equivalent Sr(1)O12 cuboctahedra, corners with ten equivalent Ba(1)O12 cuboctahedra, faces with two equivalent Sr(1)O12 cuboctahedra, faces with four equivalent Ba(1)O12 cuboctahedra, faces with four equivalent Ti(1)O6 octahedra, and faces with four equivalent Ti(2)O6 octahedra. Both Sr(1)-O(1) bond lengths are 2.75 Å. Both Sr(1)-O(2) bond lengths are 2.83 Å. There are four shorter (2.75 Å) and four longer (2.93 Å) Sr(1)-O(3) bond lengths. There are two inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms to form TiO6 octahedra that share corners with two equivalent Ti(2)O6 octahedra, corners with four equivalent Ti(1)O6 octahedra, faces with two equivalent Sr(1)O12 cuboctahedra, and faces with six equivalent Ba(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 2-10°. There is one shorter (1.85 Å) and one longer (2.25 Å) Ti(1)-O(1) bond length. Both Ti(1)-O(3) bond lengths are 1.98 Å. Both Ti(1)-O(4) bond lengths are 2.02 Å. In the second Ti site, Ti(2) is bonded to two equivalent O(2) and four equivalent O(3) atoms to form TiO6 octahedra that share corners with two equivalent Ti(2)O6 octahedra, corners with four equivalent Ti(1)O6 octahedra, faces with four equivalent Ba(1)O12 cuboctahedra, and faces with four equivalent Sr(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-10°. There is one shorter (1.84 Å) and one longer (2.25 Å) Ti(2)-O(2) bond length. All Ti(2)-O(3) bond lengths are 1.99 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 6-coordinate geometry to three equivalent Ba(1), one Sr(1), and two equivalent Ti(1) atoms. In the second O site, O(2) is bonded to two equivalent Ba(1), two equivalent Sr(1), and two equivalent Ti(2) atoms to form distorted OBa2Sr2Ti2 octahedra that share corners with four equivalent O(2)Ba2Sr2Ti2 octahedra and corners with eight equivalent O(4)Ba4Ti2 octahedra. The corner-sharing octahedral tilt angles range from 0-63°. In the third O site, O(3) is bonded in a distorted linear geometry to two equivalent Ba(1), two equivalent Sr(1), one Ti(1), and one Ti(2) atom. In the fourth O site, O(4) is bonded to four equivalent Ba(1) and two equivalent Ti(1) atoms to form distorted OBa4Ti2 octahedra that share corners with four equivalent O(2)Ba2Sr2Ti2 octahedra, corners with four equivalent O(4)Ba4Ti2 octahedra, edges with two equivalent O(4)Ba4Ti2 octahedra, and faces with two equivalent O(4)Ba4Ti2 octahedra. The corner-sharing octahedral tilt angles range from 58-63°.