Na3Ni5O8 is Caswellsilverite-like structured and crystallizes in the monoclinic C2/m space group. There are two inequivalent Na sites. In the first Na site, Na(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 NaO6 octahedra that share corners with three equivalent Ni(2)O6 octahedra, corners with three equivalent Ni(3)O6 octahedra,  an edgeedge with one Ni(2)O6 octahedra,  an edgeedge with one Ni(3)O6 octahedra,  an edgeedge with one Ni(4)O6 octahedra,  an edgeedge with one Ni(6)O6 octahedra, edges with two equivalent Na(1)O6 octahedra, edges with two equivalent Na(2)O6 octahedra, edges with two equivalent Ni(1)O6 octahedra, and edges with two equivalent Ni(5)O6 octahedra. The corner-sharing octahedral tilt angles range from 5-13°. In the second Na site, Na(2) is bonded to one O(3), one O(6), two equivalent O(1), and two equivalent O(2) atoms to form NaO6 octahedra that share corners with three equivalent Ni(1)O6 octahedra, corners with three equivalent Ni(6)O6 octahedra,  an edgeedge with one Ni(1)O6 octahedra,  an edgeedge with one Ni(4)O6 octahedra, edges with two equivalent Ni(2)O6 octahedra, edges with two equivalent Ni(3)O6 octahedra, edges with two equivalent Ni(5)O6 octahedra, and edges with four equivalent Na(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 7-12°. There are six inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to one O(3), one O(5), and four equivalent O(2) atoms to form NiO6 octahedra that share corners with three equivalent Na(2)O6 octahedra, corners with three equivalent Ni(5)O6 octahedra,  an edgeedge with one Na(2)O6 octahedra,  an edgeedge with one Ni(5)O6 octahedra, edges with two equivalent Ni(1)O6 octahedra, edges with four equivalent Na(1)O6 octahedra, and edges with four equivalent Ni(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 10-13°. In the second Ni site, Ni(2) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(5) atoms to form NiO6 octahedra that share corners with six equivalent Na(1)O6 octahedra, edges with two equivalent Na(1)O6 octahedra, edges with two equivalent Na(2)O6 octahedra, edges with two equivalent Ni(2)O6 octahedra, edges with two equivalent Ni(5)O6 octahedra, and edges with four equivalent Ni(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 5-11°. In the third Ni site, Ni(3) is bonded to two equivalent O(1), two equivalent O(4), and two equivalent O(6) atoms to form NiO6 octahedra that share corners with six equivalent Na(1)O6 octahedra, edges with two equivalent Na(1)O6 octahedra, edges with two equivalent Na(2)O6 octahedra, edges with two equivalent Ni(3)O6 octahedra, edges with two equivalent Ni(4)O6 octahedra, edges with two equivalent Ni(5)O6 octahedra, and edges with two equivalent Ni(6)O6 octahedra. The corner-sharing octahedral tilt angles range from 7-13°. In the fourth Ni site, Ni(4) is bonded to two equivalent O(4) and four equivalent O(1) atoms to form NiO6 octahedra that share corners with six equivalent Ni(5)O6 octahedra, edges with two equivalent Na(2)O6 octahedra, edges with two equivalent Ni(6)O6 octahedra, edges with four equivalent Na(1)O6 octahedra, and edges with four equivalent Ni(3)O6 octahedra. The corner-sharing octahedral tilt angles are 12°. In the fifth Ni site, Ni(5) is bonded to one O(4), one O(5), two equivalent O(1), and two equivalent O(2) atoms to form distorted NiO6 octahedra that share corners with three equivalent Ni(1)O6 octahedra, corners with three equivalent Ni(4)O6 octahedra,  an edgeedge with one Ni(1)O6 octahedra,  an edgeedge with one Ni(6)O6 octahedra, edges with two equivalent Na(2)O6 octahedra, edges with two equivalent Ni(2)O6 octahedra, edges with two equivalent Ni(3)O6 octahedra, and edges with four equivalent Na(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 12-13°. In the sixth Ni site, Ni(6) is bonded to two equivalent O(6) and four equivalent O(1) atoms to form NiO6 octahedra that share corners with six equivalent Na(2)O6 octahedra, edges with two equivalent Ni(4)O6 octahedra, edges with two equivalent Ni(5)O6 octahedra, edges with four equivalent Na(1)O6 octahedra, and edges with four equivalent Ni(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 7-10°. There are six inequivalent O sites. In the first O site, O(1) is bonded to one Na(1), one Na(2), one Ni(3), one Ni(4), one Ni(5), and one Ni(6) atom to form ONa2Ni4 octahedra that share corners with three equivalent O(1)Na2Ni4 octahedra, corners with three equivalent O(2)Na2Ni4 octahedra,  an edgeedge with one O(2)Na2Ni4 octahedra,  an edgeedge with one O(5)Na2Ni4 octahedra,  an edgeedge with one O(3)Na3Ni3 octahedra, edges with three equivalent O(1)Na2Ni4 octahedra, edges with three equivalent O(4)Na2Ni4 octahedra, and edges with three equivalent O(6)Na3Ni3 octahedra. The corner-sharing octahedral tilt angles range from 0-2°. In the second O site, O(2) is bonded to one Na(1), one Na(2), one Ni(2), one Ni(5), and two equivalent Ni(1) atoms to form ONa2Ni4 octahedra that share corners with three equivalent O(1)Na2Ni4 octahedra, corners with three equivalent O(2)Na2Ni4 octahedra,  an edgeedge with one O(1)Na2Ni4 octahedra,  an edgeedge with one O(4)Na2Ni4 octahedra,  an edgeedge with one O(6)Na3Ni3 octahedra, edges with three equivalent O(2)Na2Ni4 octahedra, edges with three equivalent O(5)Na2Ni4 octahedra, and edges with three equivalent O(3)Na3Ni3 octahedra. The corner-sharing octahedral tilt angles range from 0-5°. In the third O site, O(3) is bonded to one Na(2), two equivalent Na(1), one Ni(1), and two equivalent Ni(2) atoms to form ONa3Ni3 octahedra that share corners with three equivalent O(5)Na2Ni4 octahedra, corners with three equivalent O(6)Na3Ni3 octahedra,  an edgeedge with one O(4)Na2Ni4 octahedra,  an edgeedge with one O(3)Na3Ni3 octahedra, edges with two equivalent O(1)Na2Ni4 octahedra, edges with two equivalent O(5)Na2Ni4 octahedra, and edges with six equivalent O(2)Na2Ni4 octahedra. The corner-sharing octahedral tilt angles range from 0-4°. In the fourth O site, O(4) is bonded to two equivalent Na(1), one Ni(4), one Ni(5), and two equivalent Ni(3) atoms to form ONa2Ni4 octahedra that share corners with three equivalent O(4)Na2Ni4 octahedra, corners with three equivalent O(5)Na2Ni4 octahedra,  an edgeedge with one O(3)Na3Ni3 octahedra, edges with two equivalent O(2)Na2Ni4 octahedra, edges with three equivalent O(6)Na3Ni3 octahedra, and edges with six equivalent O(1)Na2Ni4 octahedra. The corner-sharing octahedral tilt angles range from 0-2°. In the fifth O site, O(5) is bonded to two equivalent Na(1), one Ni(1), one Ni(5), and two equivalent Ni(2) atoms to form ONa2Ni4 octahedra that share corners with three equivalent O(4)Na2Ni4 octahedra, corners with three equivalent O(3)Na3Ni3 octahedra,  an edgeedge with one O(5)Na2Ni4 octahedra,  an edgeedge with one O(6)Na3Ni3 octahedra, edges with two equivalent O(1)Na2Ni4 octahedra, edges with two equivalent O(3)Na3Ni3 octahedra, and edges with six equivalent O(2)Na2Ni4 octahedra. The corner-sharing octahedral tilt angles range from 0-4°. In the sixth O site, O(6) is bonded to one Na(2), two equivalent Na(1), one Ni(6), and two equivalent Ni(3) atoms to form ONa3Ni3 octahedra that share corners with three equivalent O(3)Na3Ni3 octahedra, corners with three equivalent O(6)Na3Ni3 octahedra,  an edgeedge with one O(5)Na2Ni4 octahedra, edges with two equivalent O(2)Na2Ni4 octahedra, edges with three equivalent O(4)Na2Ni4 octahedra, and edges with six equivalent O(1)Na2Ni4 octahedra. The corner-sharing octahedral tilt angles range from 0-4°.
Na3Ni5O8 is Caswellsilverite-like structured and crystallizes in the monoclinic C2/m space group. There are two inequivalent Na sites. In the first Na site, Na(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 NaO6 octahedra that share corners with three equivalent Ni(2)O6 octahedra, corners with three equivalent Ni(3)O6 octahedra,  an edgeedge with one Ni(2)O6 octahedra,  an edgeedge with one Ni(3)O6 octahedra,  an edgeedge with one Ni(4)O6 octahedra,  an edgeedge with one Ni(6)O6 octahedra, edges with two equivalent Na(1)O6 octahedra, edges with two equivalent Na(2)O6 octahedra, edges with two equivalent Ni(1)O6 octahedra, and edges with two equivalent Ni(5)O6 octahedra. The corner-sharing octahedral tilt angles range from 5-13°. The Na(1)-O(1) bond length is 2.31 Å. The Na(1)-O(2) bond length is 2.28 Å. The Na(1)-O(3) bond length is 2.31 Å. The Na(1)-O(4) bond length is 2.31 Å. The Na(1)-O(5) bond length is 2.30 Å. The Na(1)-O(6) bond length is 2.28 Å. In the second Na site, Na(2) is bonded to one O(3), one O(6), two equivalent O(1), and two equivalent O(2) atoms to form NaO6 octahedra that share corners with three equivalent Ni(1)O6 octahedra, corners with three equivalent Ni(6)O6 octahedra,  an edgeedge with one Ni(1)O6 octahedra,  an edgeedge with one Ni(4)O6 octahedra, edges with two equivalent Ni(2)O6 octahedra, edges with two equivalent Ni(3)O6 octahedra, edges with two equivalent Ni(5)O6 octahedra, and edges with four equivalent Na(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 7-12°. The Na(2)-O(3) bond length is 2.26 Å. The Na(2)-O(6) bond length is 2.30 Å. Both Na(2)-O(1) bond lengths are 2.27 Å. Both Na(2)-O(2) bond lengths are 2.27 Å. There are six inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to one O(3), one O(5), and four equivalent O(2) atoms to form NiO6 octahedra that share corners with three equivalent Na(2)O6 octahedra, corners with three equivalent Ni(5)O6 octahedra,  an edgeedge with one Na(2)O6 octahedra,  an edgeedge with one Ni(5)O6 octahedra, edges with two equivalent Ni(1)O6 octahedra, edges with four equivalent Na(1)O6 octahedra, and edges with four equivalent Ni(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 10-13°. The Ni(1)-O(3) bond length is 2.00 Å. The Ni(1)-O(5) bond length is 2.10 Å. There are two shorter (2.06 Å) and two longer (2.15 Å) Ni(1)-O(2) bond lengths. In the second Ni site, Ni(2) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(5) atoms to form NiO6 octahedra that share corners with six equivalent Na(1)O6 octahedra, edges with two equivalent Na(1)O6 octahedra, edges with two equivalent Na(2)O6 octahedra, edges with two equivalent Ni(2)O6 octahedra, edges with two equivalent Ni(5)O6 octahedra, and edges with four equivalent Ni(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 5-11°. Both Ni(2)-O(2) bond lengths are 1.90 Å. Both Ni(2)-O(3) bond lengths are 1.99 Å. Both Ni(2)-O(5) bond lengths are 2.01 Å. In the third Ni site, Ni(3) is bonded to two equivalent O(1), two equivalent O(4), and two equivalent O(6) atoms to form NiO6 octahedra that share corners with six equivalent Na(1)O6 octahedra, edges with two equivalent Na(1)O6 octahedra, edges with two equivalent Na(2)O6 octahedra, edges with two equivalent Ni(3)O6 octahedra, edges with two equivalent Ni(4)O6 octahedra, edges with two equivalent Ni(5)O6 octahedra, and edges with two equivalent Ni(6)O6 octahedra. The corner-sharing octahedral tilt angles range from 7-13°. Both Ni(3)-O(1) bond lengths are 1.90 Å. Both Ni(3)-O(4) bond lengths are 1.99 Å. Both Ni(3)-O(6) bond lengths are 2.07 Å. In the fourth Ni site, Ni(4) is bonded to two equivalent O(4) and four equivalent O(1) atoms to form NiO6 octahedra that share corners with six equivalent Ni(5)O6 octahedra, edges with two equivalent Na(2)O6 octahedra, edges with two equivalent Ni(6)O6 octahedra, edges with four equivalent Na(1)O6 octahedra, and edges with four equivalent Ni(3)O6 octahedra. The corner-sharing octahedral tilt angles are 12°. Both Ni(4)-O(4) bond lengths are 2.10 Å. All Ni(4)-O(1) bond lengths are 2.14 Å. In the fifth Ni site, Ni(5) is bonded to one O(4), one O(5), two equivalent O(1), and two equivalent O(2) atoms to form distorted NiO6 octahedra that share corners with three equivalent Ni(1)O6 octahedra, corners with three equivalent Ni(4)O6 octahedra,  an edgeedge with one Ni(1)O6 octahedra,  an edgeedge with one Ni(6)O6 octahedra, edges with two equivalent Na(2)O6 octahedra, edges with two equivalent Ni(2)O6 octahedra, edges with two equivalent Ni(3)O6 octahedra, and edges with four equivalent Na(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 12-13°. The Ni(5)-O(4) bond length is 2.13 Å. The Ni(5)-O(5) bond length is 2.08 Å. Both Ni(5)-O(1) bond lengths are 2.18 Å. Both Ni(5)-O(2) bond lengths are 2.15 Å. In the sixth Ni site, Ni(6) is bonded to two equivalent O(6) and four equivalent O(1) atoms to form NiO6 octahedra that share corners with six equivalent Na(2)O6 octahedra, edges with two equivalent Ni(4)O6 octahedra, edges with two equivalent Ni(5)O6 octahedra, edges with four equivalent Na(1)O6 octahedra, and edges with four equivalent Ni(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 7-10°. Both Ni(6)-O(6) bond lengths are 1.88 Å. All Ni(6)-O(1) bond lengths are 2.04 Å. There are six inequivalent O sites. In the first O site, O(1) is bonded to one Na(1), one Na(2), one Ni(3), one Ni(4), one Ni(5), and one Ni(6) atom to form ONa2Ni4 octahedra that share corners with three equivalent O(1)Na2Ni4 octahedra, corners with three equivalent O(2)Na2Ni4 octahedra,  an edgeedge with one O(2)Na2Ni4 octahedra,  an edgeedge with one O(5)Na2Ni4 octahedra,  an edgeedge with one O(3)Na3Ni3 octahedra, edges with three equivalent O(1)Na2Ni4 octahedra, edges with three equivalent O(4)Na2Ni4 octahedra, and edges with three equivalent O(6)Na3Ni3 octahedra. The corner-sharing octahedral tilt angles range from 0-2°. In the second O site, O(2) is bonded to one Na(1), one Na(2), one Ni(2), one Ni(5), and two equivalent Ni(1) atoms to form ONa2Ni4 octahedra that share corners with three equivalent O(1)Na2Ni4 octahedra, corners with three equivalent O(2)Na2Ni4 octahedra,  an edgeedge with one O(1)Na2Ni4 octahedra,  an edgeedge with one O(4)Na2Ni4 octahedra,  an edgeedge with one O(6)Na3Ni3 octahedra, edges with three equivalent O(2)Na2Ni4 octahedra, edges with three equivalent O(5)Na2Ni4 octahedra, and edges with three equivalent O(3)Na3Ni3 octahedra. The corner-sharing octahedral tilt angles range from 0-5°. In the third O site, O(3) is bonded to one Na(2), two equivalent Na(1), one Ni(1), and two equivalent Ni(2) atoms to form ONa3Ni3 octahedra that share corners with three equivalent O(5)Na2Ni4 octahedra, corners with three equivalent O(6)Na3Ni3 octahedra,  an edgeedge with one O(4)Na2Ni4 octahedra,  an edgeedge with one O(3)Na3Ni3 octahedra, edges with two equivalent O(1)Na2Ni4 octahedra, edges with two equivalent O(5)Na2Ni4 octahedra, and edges with six equivalent O(2)Na2Ni4 octahedra. The corner-sharing octahedral tilt angles range from 0-4°. In the fourth O site, O(4) is bonded to two equivalent Na(1), one Ni(4), one Ni(5), and two equivalent Ni(3) atoms to form ONa2Ni4 octahedra that share corners with three equivalent O(4)Na2Ni4 octahedra, corners with three equivalent O(5)Na2Ni4 octahedra,  an edgeedge with one O(3)Na3Ni3 octahedra, edges with two equivalent O(2)Na2Ni4 octahedra, edges with three equivalent O(6)Na3Ni3 octahedra, and edges with six equivalent O(1)Na2Ni4 octahedra. The corner-sharing octahedral tilt angles range from 0-2°. In the fifth O site, O(5) is bonded to two equivalent Na(1), one Ni(1), one Ni(5), and two equivalent Ni(2) atoms to form ONa2Ni4 octahedra that share corners with three equivalent O(4)Na2Ni4 octahedra, corners with three equivalent O(3)Na3Ni3 octahedra,  an edgeedge with one O(5)Na2Ni4 octahedra,  an edgeedge with one O(6)Na3Ni3 octahedra, edges with two equivalent O(1)Na2Ni4 octahedra, edges with two equivalent O(3)Na3Ni3 octahedra, and edges with six equivalent O(2)Na2Ni4 octahedra. The corner-sharing octahedral tilt angles range from 0-4°. In the sixth O site, O(6) is bonded to one Na(2), two equivalent Na(1), one Ni(6), and two equivalent Ni(3) atoms to form ONa3Ni3 octahedra that share corners with three equivalent O(3)Na3Ni3 octahedra, corners with three equivalent O(6)Na3Ni3 octahedra,  an edgeedge with one O(5)Na2Ni4 octahedra, edges with two equivalent O(2)Na2Ni4 octahedra, edges with three equivalent O(4)Na2Ni4 octahedra, and edges with six equivalent O(1)Na2Ni4 octahedra. The corner-sharing octahedral tilt angles range from 0-4°.