Eu2B2O5 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Eu sites. In the first Eu site, Eu(1) is bonded in a 7-coordinate geometry to one O(3), one O(4), one O(5), two equivalent O(1), and two equivalent O(2) atoms. In the second Eu site, Eu(2) is bonded in a 7-coordinate geometry to one O(1), one O(2), one O(3), two equivalent O(4), and two equivalent O(5) atoms. There are two inequivalent B sites. In the first B site, B(1) is bonded in a trigonal planar geometry to one O(3), one O(4), and one O(5) atom. In the second B site, B(2) is bonded in a trigonal planar geometry to one O(1), one O(2), and one O(3) atom. There are five inequivalent O sites. In the first O site, O(5) is bonded in a distorted single-bond geometry to one Eu(1), two equivalent Eu(2), and one B(1) atom. In the second O site, O(1) is bonded in a distorted single-bond geometry to one Eu(2), two equivalent Eu(1), and one B(2) atom. In the third O site, O(2) is bonded in a distorted single-bond geometry to one Eu(2), two equivalent Eu(1), and one B(2) atom. In the fourth O site, O(3) is bonded in a 2-coordinate geometry to one Eu(1), one Eu(2), one B(1), and one B(2) atom. In the fifth O site, O(4) is bonded in a distorted single-bond geometry to one Eu(1), two equivalent Eu(2), and one B(1) atom.
Eu2B2O5 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Eu sites. In the first Eu site, Eu(1) is bonded in a 7-coordinate geometry to one O(3), one O(4), one O(5), two equivalent O(1), and two equivalent O(2) atoms. The Eu(1)-O(3) bond length is 2.61 Å. The Eu(1)-O(4) bond length is 2.53 Å. The Eu(1)-O(5) bond length is 2.75 Å. There is one shorter (2.40 Å) and one longer (2.52 Å) Eu(1)-O(1) bond length. There is one shorter (2.48 Å) and one longer (2.66 Å) Eu(1)-O(2) bond length. In the second Eu site, Eu(2) is bonded in a 7-coordinate geometry to one O(1), one O(2), one O(3), two equivalent O(4), and two equivalent O(5) atoms. The Eu(2)-O(1) bond length is 2.54 Å. The Eu(2)-O(2) bond length is 2.46 Å. The Eu(2)-O(3) bond length is 2.96 Å. There is one shorter (2.55 Å) and one longer (2.56 Å) Eu(2)-O(4) bond length. There is one shorter (2.47 Å) and one longer (2.56 Å) Eu(2)-O(5) bond length. There are two inequivalent B sites. In the first B site, B(1) is bonded in a trigonal planar geometry to one O(3), one O(4), and one O(5) atom. The B(1)-O(3) bond length is 1.44 Å. The B(1)-O(4) bond length is 1.36 Å. The B(1)-O(5) bond length is 1.36 Å. In the second B site, B(2) is bonded in a trigonal planar geometry to one O(1), one O(2), and one O(3) atom. The B(2)-O(1) bond length is 1.36 Å. The B(2)-O(2) bond length is 1.35 Å. The B(2)-O(3) bond length is 1.42 Å. There are five inequivalent O sites. In the first O site, O(5) is bonded in a distorted single-bond geometry to one Eu(1), two equivalent Eu(2), and one B(1) atom. In the second O site, O(1) is bonded in a distorted single-bond geometry to one Eu(2), two equivalent Eu(1), and one B(2) atom. In the third O site, O(2) is bonded in a distorted single-bond geometry to one Eu(2), two equivalent Eu(1), and one B(2) atom. In the fourth O site, O(3) is bonded in a 2-coordinate geometry to one Eu(1), one Eu(2), one B(1), and one B(2) atom. In the fifth O site, O(4) is bonded in a distorted single-bond geometry to one Eu(1), two equivalent Eu(2), and one B(1) atom.