Na3NbO4 is Caswellsilverite-like structured and crystallizes in the monoclinic C2/m space group. There are six inequivalent Na sites. In the first Na site, Na(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(4) atoms to form NaO6 octahedra that share corners with two equivalent Na(2)O6 octahedra, corners with two equivalent Na(3)O6 octahedra, corners with two equivalent Na(6)O6 octahedra, edges with two equivalent Na(2)O6 octahedra, edges with two equivalent Na(5)O6 octahedra, edges with two equivalent Nb(1)O6 octahedra, edges with two equivalent Nb(2)O6 octahedra, and edges with four equivalent Na(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 14-18°. In the second Na site, Na(2) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(4) atoms to form distorted NaO6 octahedra that share corners with two equivalent Na(1)O6 octahedra, corners with four equivalent Nb(1)O6 octahedra,  an edgeedge with one Na(3)O6 octahedra,  an edgeedge with one Na(6)O6 octahedra, edges with two equivalent Na(1)O6 octahedra, edges with two equivalent Na(5)O6 octahedra, edges with two equivalent Nb(2)O6 octahedra, and edges with four equivalent Na(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 7-18°. In the third Na site, Na(3) is bonded to two equivalent O(5) and four equivalent O(2) atoms to form distorted NaO6 octahedra that share corners with two equivalent Nb(1)O6 octahedra, corners with four equivalent Na(1)O6 octahedra, edges with two equivalent Na(2)O6 octahedra, edges with two equivalent Nb(1)O6 octahedra, edges with four equivalent Na(4)O6 octahedra, and edges with four equivalent Nb(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 16-18°. In the fourth Na site, Na(4) is bonded to one O(1), one O(2), one O(3), one O(5), and two equivalent O(4) atoms to form NaO6 octahedra that share corners with three equivalent Na(5)O6 octahedra, corners with three equivalent Nb(2)O6 octahedra,  an edgeedge with one Na(3)O6 octahedra,  an edgeedge with one Na(5)O6 octahedra,  an edgeedge with one Na(6)O6 octahedra,  an edgeedge with one Nb(2)O6 octahedra, edges with two equivalent Na(1)O6 octahedra, edges with two equivalent Na(2)O6 octahedra, edges with two equivalent Na(4)O6 octahedra, and edges with two equivalent Nb(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 8-19°. In the fifth Na site, Na(5) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms to form NaO6 octahedra that share corners with six equivalent Na(4)O6 octahedra,  an edgeedge with one Na(5)O6 octahedra,  an edgeedge with one Nb(2)O6 octahedra, edges with two equivalent Na(1)O6 octahedra, edges with two equivalent Na(2)O6 octahedra, edges with two equivalent Na(4)O6 octahedra, edges with two equivalent Na(6)O6 octahedra, and edges with two equivalent Nb(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 14-19°. In the sixth Na site, Na(6) is bonded to two equivalent O(3) and four equivalent O(1) atoms to form NaO6 octahedra that share corners with two equivalent Nb(1)O6 octahedra, corners with four equivalent Na(1)O6 octahedra, edges with two equivalent Na(2)O6 octahedra, edges with two equivalent Nb(1)O6 octahedra, edges with four equivalent Na(4)O6 octahedra, and edges with four equivalent Na(5)O6 octahedra. The corner-sharing octahedral tilt angles range from 8-14°. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one O(3), one O(5), two equivalent O(1), and two equivalent O(2) atoms to form NbO6 octahedra that share  a cornercorner with one Na(3)O6 octahedra,  a cornercorner with one Na(6)O6 octahedra, corners with four equivalent Na(2)O6 octahedra,  an edgeedge with one Na(3)O6 octahedra,  an edgeedge with one Na(6)O6 octahedra, edges with two equivalent Na(1)O6 octahedra, edges with two equivalent Na(5)O6 octahedra, edges with two equivalent Nb(2)O6 octahedra, and edges with four equivalent Na(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 7-16°. In the second Nb site, Nb(2) is bonded to two equivalent O(2), two equivalent O(4), and two equivalent O(5) atoms to form NbO6 octahedra that share corners with six equivalent Na(4)O6 octahedra,  an edgeedge with one Na(5)O6 octahedra,  an edgeedge with one Nb(2)O6 octahedra, edges with two equivalent Na(1)O6 octahedra, edges with two equivalent Na(2)O6 octahedra, edges with two equivalent Na(3)O6 octahedra, edges with two equivalent Na(4)O6 octahedra, and edges with two equivalent Nb(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 8-14°. There are five inequivalent O sites. In the first O site, O(1) is bonded to one Na(1), one Na(2), one Na(4), one Na(5), one Na(6), and one Nb(1) atom to form distorted ONa5Nb octahedra that share corners with three equivalent O(2)Na4Nb2 octahedra, corners with three equivalent O(1)Na5Nb octahedra,  an edgeedge with one O(5)Na3Nb3 octahedra, edges with two equivalent O(2)Na4Nb2 octahedra, edges with two equivalent O(1)Na5Nb octahedra, and edges with four equivalent O(4)Na5Nb octahedra. The corner-sharing octahedral tilt angles range from 0-11°. In the second O site, O(2) is bonded to one Na(1), one Na(2), one Na(3), one Na(4), one Nb(1), and one Nb(2) atom to form distorted ONa4Nb2 octahedra that share corners with three equivalent O(2)Na4Nb2 octahedra, corners with three equivalent O(1)Na5Nb octahedra, edges with two equivalent O(2)Na4Nb2 octahedra, edges with two equivalent O(1)Na5Nb octahedra, edges with three equivalent O(5)Na3Nb3 octahedra, and edges with four equivalent O(4)Na5Nb octahedra. The corner-sharing octahedral tilt angles range from 0-16°. In the third O site, O(3) is bonded in a 6-coordinate geometry to one Na(6), two equivalent Na(4), two equivalent Na(5), and one Nb(1) atom. In the fourth O site, O(4) is bonded to one Na(1), one Na(2), one Na(5), two equivalent Na(4), and one Nb(2) atom to form distorted ONa5Nb octahedra that share corners with two equivalent O(5)Na3Nb3 octahedra, corners with two equivalent O(4)Na5Nb octahedra,  an edgeedge with one O(5)Na3Nb3 octahedra, edges with two equivalent O(4)Na5Nb octahedra, edges with four equivalent O(2)Na4Nb2 octahedra, and edges with four equivalent O(1)Na5Nb octahedra. The corner-sharing octahedral tilt angles range from 0-19°. In the fifth O site, O(5) is bonded to one Na(3), two equivalent Na(4), one Nb(1), and two equivalent Nb(2) atoms to form ONa3Nb3 octahedra that share  a cornercorner with one O(5)Na3Nb3 octahedra, corners with four equivalent O(4)Na5Nb octahedra,  an edgeedge with one O(5)Na3Nb3 octahedra, edges with two equivalent O(1)Na5Nb octahedra, edges with two equivalent O(4)Na5Nb octahedra, and edges with six equivalent O(2)Na4Nb2 octahedra. The corner-sharing octahedral tilt angles range from 0-12°.
Na3NbO4 is Caswellsilverite-like structured and crystallizes in the monoclinic C2/m space group. There are six inequivalent Na sites. In the first Na site, Na(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(4) atoms to form NaO6 octahedra that share corners with two equivalent Na(2)O6 octahedra, corners with two equivalent Na(3)O6 octahedra, corners with two equivalent Na(6)O6 octahedra, edges with two equivalent Na(2)O6 octahedra, edges with two equivalent Na(5)O6 octahedra, edges with two equivalent Nb(1)O6 octahedra, edges with two equivalent Nb(2)O6 octahedra, and edges with four equivalent Na(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 14-18°. Both Na(1)-O(1) bond lengths are 2.33 Å. Both Na(1)-O(2) bond lengths are 2.33 Å. Both Na(1)-O(4) bond lengths are 2.39 Å. In the second Na site, Na(2) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(4) atoms to form distorted NaO6 octahedra that share corners with two equivalent Na(1)O6 octahedra, corners with four equivalent Nb(1)O6 octahedra,  an edgeedge with one Na(3)O6 octahedra,  an edgeedge with one Na(6)O6 octahedra, edges with two equivalent Na(1)O6 octahedra, edges with two equivalent Na(5)O6 octahedra, edges with two equivalent Nb(2)O6 octahedra, and edges with four equivalent Na(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 7-18°. Both Na(2)-O(1) bond lengths are 2.48 Å. Both Na(2)-O(2) bond lengths are 2.64 Å. Both Na(2)-O(4) bond lengths are 2.27 Å. In the third Na site, Na(3) is bonded to two equivalent O(5) and four equivalent O(2) atoms to form distorted NaO6 octahedra that share corners with two equivalent Nb(1)O6 octahedra, corners with four equivalent Na(1)O6 octahedra, edges with two equivalent Na(2)O6 octahedra, edges with two equivalent Nb(1)O6 octahedra, edges with four equivalent Na(4)O6 octahedra, and edges with four equivalent Nb(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 16-18°. Both Na(3)-O(5) bond lengths are 2.43 Å. All Na(3)-O(2) bond lengths are 2.33 Å. In the fourth Na site, Na(4) is bonded to one O(1), one O(2), one O(3), one O(5), and two equivalent O(4) atoms to form NaO6 octahedra that share corners with three equivalent Na(5)O6 octahedra, corners with three equivalent Nb(2)O6 octahedra,  an edgeedge with one Na(3)O6 octahedra,  an edgeedge with one Na(5)O6 octahedra,  an edgeedge with one Na(6)O6 octahedra,  an edgeedge with one Nb(2)O6 octahedra, edges with two equivalent Na(1)O6 octahedra, edges with two equivalent Na(2)O6 octahedra, edges with two equivalent Na(4)O6 octahedra, and edges with two equivalent Nb(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 8-19°. The Na(4)-O(1) bond length is 2.35 Å. The Na(4)-O(2) bond length is 2.48 Å. The Na(4)-O(3) bond length is 2.28 Å. The Na(4)-O(5) bond length is 2.54 Å. There is one shorter (2.30 Å) and one longer (2.57 Å) Na(4)-O(4) bond length. In the fifth Na site, Na(5) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms to form NaO6 octahedra that share corners with six equivalent Na(4)O6 octahedra,  an edgeedge with one Na(5)O6 octahedra,  an edgeedge with one Nb(2)O6 octahedra, edges with two equivalent Na(1)O6 octahedra, edges with two equivalent Na(2)O6 octahedra, edges with two equivalent Na(4)O6 octahedra, edges with two equivalent Na(6)O6 octahedra, and edges with two equivalent Nb(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 14-19°. Both Na(5)-O(1) bond lengths are 2.40 Å. Both Na(5)-O(3) bond lengths are 2.35 Å. Both Na(5)-O(4) bond lengths are 2.37 Å. In the sixth Na site, Na(6) is bonded to two equivalent O(3) and four equivalent O(1) atoms to form NaO6 octahedra that share corners with two equivalent Nb(1)O6 octahedra, corners with four equivalent Na(1)O6 octahedra, edges with two equivalent Na(2)O6 octahedra, edges with two equivalent Nb(1)O6 octahedra, edges with four equivalent Na(4)O6 octahedra, and edges with four equivalent Na(5)O6 octahedra. The corner-sharing octahedral tilt angles range from 8-14°. Both Na(6)-O(3) bond lengths are 2.73 Å. All Na(6)-O(1) bond lengths are 2.30 Å. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one O(3), one O(5), two equivalent O(1), and two equivalent O(2) atoms to form NbO6 octahedra that share  a cornercorner with one Na(3)O6 octahedra,  a cornercorner with one Na(6)O6 octahedra, corners with four equivalent Na(2)O6 octahedra,  an edgeedge with one Na(3)O6 octahedra,  an edgeedge with one Na(6)O6 octahedra, edges with two equivalent Na(1)O6 octahedra, edges with two equivalent Na(5)O6 octahedra, edges with two equivalent Nb(2)O6 octahedra, and edges with four equivalent Na(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 7-16°. The Nb(1)-O(3) bond length is 1.91 Å. The Nb(1)-O(5) bond length is 2.18 Å. Both Nb(1)-O(1) bond lengths are 1.91 Å. Both Nb(1)-O(2) bond lengths are 2.21 Å. In the second Nb site, Nb(2) is bonded to two equivalent O(2), two equivalent O(4), and two equivalent O(5) atoms to form NbO6 octahedra that share corners with six equivalent Na(4)O6 octahedra,  an edgeedge with one Na(5)O6 octahedra,  an edgeedge with one Nb(2)O6 octahedra, edges with two equivalent Na(1)O6 octahedra, edges with two equivalent Na(2)O6 octahedra, edges with two equivalent Na(3)O6 octahedra, edges with two equivalent Na(4)O6 octahedra, and edges with two equivalent Nb(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 8-14°. Both Nb(2)-O(2) bond lengths are 2.02 Å. Both Nb(2)-O(4) bond lengths are 1.90 Å. Both Nb(2)-O(5) bond lengths are 2.23 Å. There are five inequivalent O sites. In the first O site, O(1) is bonded to one Na(1), one Na(2), one Na(4), one Na(5), one Na(6), and one Nb(1) atom to form distorted ONa5Nb octahedra that share corners with three equivalent O(2)Na4Nb2 octahedra, corners with three equivalent O(1)Na5Nb octahedra,  an edgeedge with one O(5)Na3Nb3 octahedra, edges with two equivalent O(2)Na4Nb2 octahedra, edges with two equivalent O(1)Na5Nb octahedra, and edges with four equivalent O(4)Na5Nb octahedra. The corner-sharing octahedral tilt angles range from 0-11°. In the second O site, O(2) is bonded to one Na(1), one Na(2), one Na(3), one Na(4), one Nb(1), and one Nb(2) atom to form distorted ONa4Nb2 octahedra that share corners with three equivalent O(2)Na4Nb2 octahedra, corners with three equivalent O(1)Na5Nb octahedra, edges with two equivalent O(2)Na4Nb2 octahedra, edges with two equivalent O(1)Na5Nb octahedra, edges with three equivalent O(5)Na3Nb3 octahedra, and edges with four equivalent O(4)Na5Nb octahedra. The corner-sharing octahedral tilt angles range from 0-16°. In the third O site, O(3) is bonded in a 6-coordinate geometry to one Na(6), two equivalent Na(4), two equivalent Na(5), and one Nb(1) atom. In the fourth O site, O(4) is bonded to one Na(1), one Na(2), one Na(5), two equivalent Na(4), and one Nb(2) atom to form distorted ONa5Nb octahedra that share corners with two equivalent O(5)Na3Nb3 octahedra, corners with two equivalent O(4)Na5Nb octahedra,  an edgeedge with one O(5)Na3Nb3 octahedra, edges with two equivalent O(4)Na5Nb octahedra, edges with four equivalent O(2)Na4Nb2 octahedra, and edges with four equivalent O(1)Na5Nb octahedra. The corner-sharing octahedral tilt angles range from 0-19°. In the fifth O site, O(5) is bonded to one Na(3), two equivalent Na(4), one Nb(1), and two equivalent Nb(2) atoms to form ONa3Nb3 octahedra that share  a cornercorner with one O(5)Na3Nb3 octahedra, corners with four equivalent O(4)Na5Nb octahedra,  an edgeedge with one O(5)Na3Nb3 octahedra, edges with two equivalent O(1)Na5Nb octahedra, edges with two equivalent O(4)Na5Nb octahedra, and edges with six equivalent O(2)Na4Nb2 octahedra. The corner-sharing octahedral tilt angles range from 0-12°.