BaFeSi4O10 crystallizes in the orthorhombic P2_12_12 space group. Ba(1) is bonded in a 10-coordinate geometry to two equivalent O(2), two equivalent O(3), two equivalent O(5), and four equivalent O(1) atoms. Fe(1) is bonded in a rectangular see-saw-like geometry to two equivalent O(1) and two equivalent O(2) atoms. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(3), one O(4), and one O(5) atom to form corner-sharing SiO4 tetrahedra. In the second Si site, Si(2) is bonded to one O(2), one O(3), one O(4), and one O(5) atom to form corner-sharing SiO4 tetrahedra. There are five inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to two equivalent Ba(1), one Fe(1), and one Si(1) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Ba(1), one Fe(1), and one Si(2) atom. In the third O site, O(3) is bonded in a distorted bent 150 degrees geometry to one Ba(1), one Si(1), and one Si(2) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one Si(1) and one Si(2) atom. In the fifth O site, O(5) is bonded in a distorted bent 150 degrees geometry to one Ba(1), one Si(1), and one Si(2) atom.
BaFeSi4O10 crystallizes in the orthorhombic P2_12_12 space group. Ba(1) is bonded in a 10-coordinate geometry to two equivalent O(2), two equivalent O(3), two equivalent O(5), and four equivalent O(1) atoms. Both Ba(1)-O(2) bond lengths are 2.78 Å. Both Ba(1)-O(3) bond lengths are 2.97 Å. Both Ba(1)-O(5) bond lengths are 2.93 Å. There are two shorter (2.74 Å) and two longer (3.28 Å) Ba(1)-O(1) bond lengths. Fe(1) is bonded in a rectangular see-saw-like geometry to two equivalent O(1) and two equivalent O(2) atoms. Both Fe(1)-O(1) bond lengths are 2.02 Å. Both Fe(1)-O(2) bond lengths are 1.92 Å. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(3), one O(4), and one O(5) atom to form corner-sharing SiO4 tetrahedra. The Si(1)-O(1) bond length is 1.59 Å. The Si(1)-O(3) bond length is 1.64 Å. The Si(1)-O(4) bond length is 1.61 Å. The Si(1)-O(5) bond length is 1.62 Å. In the second Si site, Si(2) is bonded to one O(2), one O(3), one O(4), and one O(5) atom to form corner-sharing SiO4 tetrahedra. The Si(2)-O(2) bond length is 1.58 Å. The Si(2)-O(3) bond length is 1.63 Å. The Si(2)-O(4) bond length is 1.61 Å. The Si(2)-O(5) bond length is 1.63 Å. There are five inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to two equivalent Ba(1), one Fe(1), and one Si(1) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Ba(1), one Fe(1), and one Si(2) atom. In the third O site, O(3) is bonded in a distorted bent 150 degrees geometry to one Ba(1), one Si(1), and one Si(2) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one Si(1) and one Si(2) atom. In the fifth O site, O(5) is bonded in a distorted bent 150 degrees geometry to one Ba(1), one Si(1), and one Si(2) atom.