SrEuSmNbO6 is Orthorhombic Perovskite-derived structured and crystallizes in the orthorhombic P222 space group. There are four inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a distorted square co-planar geometry to four equivalent O(1) and four equivalent O(5) atoms. In the second Sr site, Sr(2) is bonded in a distorted square co-planar geometry to four equivalent O(3) and four equivalent O(4) atoms. In the third Sr site, Sr(3) is bonded in a distorted square co-planar geometry to four equivalent O(3) and four equivalent O(5) atoms. In the fourth Sr site, Sr(4) is bonded in a distorted square co-planar geometry to four equivalent O(1) and four equivalent O(6) atoms. There are four inequivalent Eu sites. In the first Eu site, Eu(1) is bonded in a distorted square co-planar geometry to four equivalent O(6) atoms. In the second Eu site, Eu(2) is bonded in a distorted square co-planar geometry to four equivalent O(2) atoms. In the third Eu site, Eu(3) is bonded to four equivalent O(1), four equivalent O(2), and four equivalent O(3) atoms to form EuO12 cuboctahedra that share faces with four equivalent Sm(1)O6 octahedra and faces with four equivalent Nb(1)O6 octahedra. In the fourth Eu site, Eu(4) is bonded to four equivalent O(4), four equivalent O(5), and four equivalent O(6) atoms to form EuO12 cuboctahedra that share faces with four equivalent Sm(1)O6 octahedra and faces with four equivalent Nb(1)O6 octahedra. Sm(1) is bonded to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(6) atom to form SmO6 octahedra that share corners with six equivalent Nb(1)O6 octahedra,  a faceface with one Eu(3)O12 cuboctahedra, and  a faceface with one Eu(4)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 27-28°. Nb(1) is bonded to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(6) atom to form NbO6 octahedra that share corners with six equivalent Sm(1)O6 octahedra,  a faceface with one Eu(3)O12 cuboctahedra, and  a faceface with one Eu(4)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 27-28°. There are six inequivalent O sites. In the first O site, O(5) is bonded in a 3-coordinate geometry to one Sr(1), one Sr(3), one Eu(4), one Sm(1), and one Nb(1) atom. In the second O site, O(6) is bonded in a 3-coordinate geometry to one Sr(4), one Eu(1), one Eu(4), one Sm(1), and one Nb(1) atom. In the third O site, O(1) is bonded in a 3-coordinate geometry to one Sr(1), one Sr(4), one Eu(3), one Sm(1), and one Nb(1) atom. In the fourth O site, O(2) is bonded in a 3-coordinate geometry to one Eu(2), one Eu(3), one Sm(1), and one Nb(1) atom. In the fifth O site, O(3) is bonded in a 3-coordinate geometry to one Sr(2), one Sr(3), one Eu(3), one Sm(1), and one Nb(1) atom. In the sixth O site, O(4) is bonded in a 3-coordinate geometry to one Sr(2), one Eu(4), one Sm(1), and one Nb(1) atom.
SrEuSmNbO6 is Orthorhombic Perovskite-derived structured and crystallizes in the orthorhombic P222 space group. There are four inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a distorted square co-planar geometry to four equivalent O(1) and four equivalent O(5) atoms. All Sr(1)-O(1) bond lengths are 3.10 Å. All Sr(1)-O(5) bond lengths are 2.51 Å. In the second Sr site, Sr(2) is bonded in a distorted square co-planar geometry to four equivalent O(3) and four equivalent O(4) atoms. All Sr(2)-O(3) bond lengths are 3.10 Å. All Sr(2)-O(4) bond lengths are 2.50 Å. In the third Sr site, Sr(3) is bonded in a distorted square co-planar geometry to four equivalent O(3) and four equivalent O(5) atoms. All Sr(3)-O(3) bond lengths are 2.51 Å. All Sr(3)-O(5) bond lengths are 3.10 Å. In the fourth Sr site, Sr(4) is bonded in a distorted square co-planar geometry to four equivalent O(1) and four equivalent O(6) atoms. All Sr(4)-O(1) bond lengths are 2.50 Å. All Sr(4)-O(6) bond lengths are 3.10 Å. There are four inequivalent Eu sites. In the first Eu site, Eu(1) is bonded in a distorted square co-planar geometry to four equivalent O(6) atoms. All Eu(1)-O(6) bond lengths are 2.48 Å. In the second Eu site, Eu(2) is bonded in a distorted square co-planar geometry to four equivalent O(2) atoms. All Eu(2)-O(2) bond lengths are 2.48 Å. In the third Eu site, Eu(3) is bonded to four equivalent O(1), four equivalent O(2), and four equivalent O(3) atoms to form EuO12 cuboctahedra that share faces with four equivalent Sm(1)O6 octahedra and faces with four equivalent Nb(1)O6 octahedra. All Eu(3)-O(1) bond lengths are 2.99 Å. All Eu(3)-O(2) bond lengths are 3.00 Å. All Eu(3)-O(3) bond lengths are 2.99 Å. In the fourth Eu site, Eu(4) is bonded to four equivalent O(4), four equivalent O(5), and four equivalent O(6) atoms to form EuO12 cuboctahedra that share faces with four equivalent Sm(1)O6 octahedra and faces with four equivalent Nb(1)O6 octahedra. All Eu(4)-O(4) bond lengths are 2.99 Å. All Eu(4)-O(5) bond lengths are 2.98 Å. All Eu(4)-O(6) bond lengths are 2.99 Å. Sm(1) is bonded to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(6) atom to form SmO6 octahedra that share corners with six equivalent Nb(1)O6 octahedra,  a faceface with one Eu(3)O12 cuboctahedra, and  a faceface with one Eu(4)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 27-28°. The Sm(1)-O(1) bond length is 2.32 Å. The Sm(1)-O(2) bond length is 2.32 Å. The Sm(1)-O(3) bond length is 2.32 Å. The Sm(1)-O(4) bond length is 2.31 Å. The Sm(1)-O(5) bond length is 2.32 Å. The Sm(1)-O(6) bond length is 2.32 Å. Nb(1) is bonded to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(6) atom to form NbO6 octahedra that share corners with six equivalent Sm(1)O6 octahedra,  a faceface with one Eu(3)O12 cuboctahedra, and  a faceface with one Eu(4)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 27-28°. The Nb(1)-O(1) bond length is 2.04 Å. The Nb(1)-O(2) bond length is 2.05 Å. The Nb(1)-O(3) bond length is 2.04 Å. The Nb(1)-O(4) bond length is 2.04 Å. The Nb(1)-O(5) bond length is 2.04 Å. The Nb(1)-O(6) bond length is 2.05 Å. There are six inequivalent O sites. In the first O site, O(5) is bonded in a 3-coordinate geometry to one Sr(1), one Sr(3), one Eu(4), one Sm(1), and one Nb(1) atom. In the second O site, O(6) is bonded in a 3-coordinate geometry to one Sr(4), one Eu(1), one Eu(4), one Sm(1), and one Nb(1) atom. In the third O site, O(1) is bonded in a 3-coordinate geometry to one Sr(1), one Sr(4), one Eu(3), one Sm(1), and one Nb(1) atom. In the fourth O site, O(2) is bonded in a 3-coordinate geometry to one Eu(2), one Eu(3), one Sm(1), and one Nb(1) atom. In the fifth O site, O(3) is bonded in a 3-coordinate geometry to one Sr(2), one Sr(3), one Eu(3), one Sm(1), and one Nb(1) atom. In the sixth O site, O(4) is bonded in a 3-coordinate geometry to one Sr(2), one Eu(4), one Sm(1), and one Nb(1) atom.