Bi4(B2O5)3 crystallizes in the monoclinic C2/c space group. There are three inequivalent B sites. In the first B site, B(1) is bonded to one O(1), one O(2), one O(4), and one O(5) atom to form corner-sharing BO4 tetrahedra. In the second B site, B(2) is bonded to one O(1), one O(3), one O(6), and one O(8) atom to form corner-sharing BO4 tetrahedra. In the third B site, B(3) is bonded to one O(2), one O(4), and two equivalent O(7) atoms to form a mixture of corner and edge-sharing BO4 tetrahedra. There are two inequivalent Bi sites. In the first Bi site, Bi(1) is bonded in a 7-coordinate geometry to one O(8), two equivalent O(3), two equivalent O(5), and two equivalent O(6) atoms. In the second Bi site, Bi(2) is bonded in a 8-coordinate geometry to one O(1), one O(2), one O(3), one O(4), one O(5), one O(6), and two equivalent O(7) atoms. There are eight inequivalent O sites. In the first O site, O(8) is bonded in a 2-coordinate geometry to two equivalent B(2) and two equivalent Bi(1) atoms. In the second O site, O(1) is bonded in a distorted bent 120 degrees geometry to one B(1), one B(2), and one Bi(2) atom. In the third O site, O(2) is bonded in a distorted bent 120 degrees geometry to one B(1), one B(3), and one Bi(2) atom. In the fourth O site, O(3) is bonded in a distorted single-bond geometry to one B(2), one Bi(2), and two equivalent Bi(1) atoms. In the fifth O site, O(4) is bonded in a distorted bent 120 degrees geometry to one B(1), one B(3), and one Bi(2) atom. In the sixth O site, O(5) is bonded in a distorted single-bond geometry to one B(1), one Bi(2), and two equivalent Bi(1) atoms. In the seventh O site, O(6) is bonded in a distorted single-bond geometry to one B(2), one Bi(2), and two equivalent Bi(1) atoms. In the eighth O site, O(7) is bonded in a distorted L-shaped geometry to two equivalent B(3) and two equivalent Bi(2) atoms.
Bi4(B2O5)3 crystallizes in the monoclinic C2/c space group. There are three inequivalent B sites. In the first B site, B(1) is bonded to one O(1), one O(2), one O(4), and one O(5) atom to form corner-sharing BO4 tetrahedra. The B(1)-O(1) bond length is 1.51 Å. The B(1)-O(2) bond length is 1.49 Å. The B(1)-O(4) bond length is 1.47 Å. The B(1)-O(5) bond length is 1.48 Å. In the second B site, B(2) is bonded to one O(1), one O(3), one O(6), and one O(8) atom to form corner-sharing BO4 tetrahedra. The B(2)-O(1) bond length is 1.49 Å. The B(2)-O(3) bond length is 1.44 Å. The B(2)-O(6) bond length is 1.49 Å. The B(2)-O(8) bond length is 1.52 Å. In the third B site, B(3) is bonded to one O(2), one O(4), and two equivalent O(7) atoms to form a mixture of corner and edge-sharing BO4 tetrahedra. The B(3)-O(2) bond length is 1.45 Å. The B(3)-O(4) bond length is 1.46 Å. There is one shorter (1.53 Å) and one longer (1.55 Å) B(3)-O(7) bond length. There are two inequivalent Bi sites. In the first Bi site, Bi(1) is bonded in a 7-coordinate geometry to one O(8), two equivalent O(3), two equivalent O(5), and two equivalent O(6) atoms. The Bi(1)-O(8) bond length is 2.45 Å. There is one shorter (2.26 Å) and one longer (2.77 Å) Bi(1)-O(3) bond length. There is one shorter (2.51 Å) and one longer (2.67 Å) Bi(1)-O(5) bond length. There is one shorter (2.35 Å) and one longer (2.41 Å) Bi(1)-O(6) bond length. In the second Bi site, Bi(2) is bonded in a 8-coordinate geometry to one O(1), one O(2), one O(3), one O(4), one O(5), one O(6), and two equivalent O(7) atoms. The Bi(2)-O(1) bond length is 2.36 Å. The Bi(2)-O(2) bond length is 2.78 Å. The Bi(2)-O(3) bond length is 2.46 Å. The Bi(2)-O(4) bond length is 2.44 Å. The Bi(2)-O(5) bond length is 2.30 Å. The Bi(2)-O(6) bond length is 2.57 Å. There is one shorter (2.54 Å) and one longer (2.82 Å) Bi(2)-O(7) bond length. There are eight inequivalent O sites. In the first O site, O(8) is bonded in a 2-coordinate geometry to two equivalent B(2) and two equivalent Bi(1) atoms. In the second O site, O(1) is bonded in a distorted bent 120 degrees geometry to one B(1), one B(2), and one Bi(2) atom. In the third O site, O(2) is bonded in a distorted bent 120 degrees geometry to one B(1), one B(3), and one Bi(2) atom. In the fourth O site, O(3) is bonded in a distorted single-bond geometry to one B(2), one Bi(2), and two equivalent Bi(1) atoms. In the fifth O site, O(4) is bonded in a distorted bent 120 degrees geometry to one B(1), one B(3), and one Bi(2) atom. In the sixth O site, O(5) is bonded in a distorted single-bond geometry to one B(1), one Bi(2), and two equivalent Bi(1) atoms. In the seventh O site, O(6) is bonded in a distorted single-bond geometry to one B(2), one Bi(2), and two equivalent Bi(1) atoms. In the eighth O site, O(7) is bonded in a distorted L-shaped geometry to two equivalent B(3) and two equivalent Bi(2) atoms.