SrEuCeNbO6 crystallizes in the tetragonal P-4n2 space group. Sr(1) is bonded in a distorted body-centered cubic geometry to four equivalent O(1) and four equivalent O(2) atoms. Eu(1) is bonded in a distorted body-centered cubic geometry to four equivalent O(1) and four equivalent O(2) atoms. Ce(1) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form CeO6 octahedra that share corners with six equivalent Nb(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-33°. Nb(1) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form NbO6 octahedra that share corners with six equivalent Ce(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-33°. There are two inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Sr(1), two equivalent Eu(1), one Ce(1), and one Nb(1) atom to form distorted OSr2CeEu2Nb octahedra that share corners with six equivalent O(1)Sr2CeEu2Nb octahedra, corners with eight equivalent O(2)SrCeEuNb tetrahedra, edges with four equivalent O(1)Sr2CeEu2Nb octahedra, and edges with eight equivalent O(2)SrCeEuNb tetrahedra. The corner-sharing octahedral tilt angles range from 0-4°. In the second O site, O(2) is bonded to one Sr(1), one Eu(1), one Ce(1), and one Nb(1) atom to form distorted OSrCeEuNb tetrahedra that share corners with four equivalent O(1)Sr2CeEu2Nb octahedra, corners with ten equivalent O(2)SrCeEuNb tetrahedra, edges with four equivalent O(1)Sr2CeEu2Nb octahedra, and  an edgeedge with one O(2)SrCeEuNb tetrahedra. The corner-sharing octahedral tilt angles range from 66-67°.
SrEuCeNbO6 crystallizes in the tetragonal P-4n2 space group. Sr(1) is bonded in a distorted body-centered cubic geometry to four equivalent O(1) and four equivalent O(2) atoms. All Sr(1)-O(1) bond lengths are 2.93 Å. All Sr(1)-O(2) bond lengths are 2.61 Å. Eu(1) is bonded in a distorted body-centered cubic geometry to four equivalent O(1) and four equivalent O(2) atoms. All Eu(1)-O(1) bond lengths are 2.93 Å. All Eu(1)-O(2) bond lengths are 2.57 Å. Ce(1) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form CeO6 octahedra that share corners with six equivalent Nb(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-33°. Both Ce(1)-O(1) bond lengths are 2.25 Å. All Ce(1)-O(2) bond lengths are 2.29 Å. Nb(1) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form NbO6 octahedra that share corners with six equivalent Ce(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-33°. Both Nb(1)-O(1) bond lengths are 2.04 Å. All Nb(1)-O(2) bond lengths are 2.03 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Sr(1), two equivalent Eu(1), one Ce(1), and one Nb(1) atom to form distorted OSr2CeEu2Nb octahedra that share corners with six equivalent O(1)Sr2CeEu2Nb octahedra, corners with eight equivalent O(2)SrCeEuNb tetrahedra, edges with four equivalent O(1)Sr2CeEu2Nb octahedra, and edges with eight equivalent O(2)SrCeEuNb tetrahedra. The corner-sharing octahedral tilt angles range from 0-4°. In the second O site, O(2) is bonded to one Sr(1), one Eu(1), one Ce(1), and one Nb(1) atom to form distorted OSrCeEuNb tetrahedra that share corners with four equivalent O(1)Sr2CeEu2Nb octahedra, corners with ten equivalent O(2)SrCeEuNb tetrahedra, edges with four equivalent O(1)Sr2CeEu2Nb octahedra, and  an edgeedge with one O(2)SrCeEuNb tetrahedra. The corner-sharing octahedral tilt angles range from 66-67°.