Eu2NiO4 is (La,Ba)CuO4 structured and crystallizes in the tetragonal I4/mmm space group. Eu(1) is bonded in a 9-coordinate geometry to four equivalent O(1) and five equivalent O(2) atoms. Ni(1) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form corner-sharing NiO6 octahedra. The corner-sharing octahedra are not tilted. There are two inequivalent O sites. In the first O site, O(2) is bonded to five equivalent Eu(1) and one Ni(1) atom to form distorted OEu5Ni octahedra that share corners with five equivalent O(2)Eu5Ni octahedra, corners with twelve equivalent O(1)Eu4Ni2 octahedra, edges with eight equivalent O(2)Eu5Ni octahedra, and faces with four equivalent O(1)Eu4Ni2 octahedra. The corner-sharing octahedral tilt angles range from 0-52°. In the second O site, O(1) is bonded to four equivalent Eu(1) and two equivalent Ni(1) atoms to form distorted OEu4Ni2 octahedra that share corners with two equivalent O(1)Eu4Ni2 octahedra, corners with twelve equivalent O(2)Eu5Ni octahedra, edges with two equivalent O(1)Eu4Ni2 octahedra, faces with four equivalent O(1)Eu4Ni2 octahedra, and faces with four equivalent O(2)Eu5Ni octahedra. The corner-sharing octahedral tilt angles range from 0-52°.
Eu2NiO4 is (La,Ba)CuO4 structured and crystallizes in the tetragonal I4/mmm space group. Eu(1) is bonded in a 9-coordinate geometry to four equivalent O(1) and five equivalent O(2) atoms. All Eu(1)-O(1) bond lengths are 2.58 Å. There is one shorter (2.23 Å) and four longer (2.71 Å) Eu(1)-O(2) bond lengths. Ni(1) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form corner-sharing NiO6 octahedra. The corner-sharing octahedra are not tilted. Both Ni(1)-O(2) bond lengths are 2.15 Å. All Ni(1)-O(1) bond lengths are 1.90 Å. There are two inequivalent O sites. In the first O site, O(2) is bonded to five equivalent Eu(1) and one Ni(1) atom to form distorted OEu5Ni octahedra that share corners with five equivalent O(2)Eu5Ni octahedra, corners with twelve equivalent O(1)Eu4Ni2 octahedra, edges with eight equivalent O(2)Eu5Ni octahedra, and faces with four equivalent O(1)Eu4Ni2 octahedra. The corner-sharing octahedral tilt angles range from 0-52°. In the second O site, O(1) is bonded to four equivalent Eu(1) and two equivalent Ni(1) atoms to form distorted OEu4Ni2 octahedra that share corners with two equivalent O(1)Eu4Ni2 octahedra, corners with twelve equivalent O(2)Eu5Ni octahedra, edges with two equivalent O(1)Eu4Ni2 octahedra, faces with four equivalent O(1)Eu4Ni2 octahedra, and faces with four equivalent O(2)Eu5Ni octahedra. The corner-sharing octahedral tilt angles range from 0-52°.