Na3Ba(PO4)2 crystallizes in the trigonal P-3m1 space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 1-coordinate geometry to one O(1) atom. In the second Na site, Na(2) is bonded to six equivalent O(2) atoms to form NaO6 octahedra that share corners with six equivalent P(1)O4 tetrahedra and faces with two equivalent Ba(1)O12 cuboctahedra. Ba(1) is bonded to six equivalent O(1) and six equivalent O(2) atoms to form distorted BaO12 cuboctahedra that share edges with six equivalent Ba(1)O12 cuboctahedra, edges with six equivalent P(1)O4 tetrahedra, and faces with two equivalent Na(2)O6 octahedra. P(1) is bonded to one O(1) and three equivalent O(2) atoms to form PO4 tetrahedra that share corners with three equivalent Na(2)O6 octahedra and edges with three equivalent Ba(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles are 18°. There are two inequivalent O sites. In the first O site, O(1) is bonded in a distorted linear geometry to one Na(1), three equivalent Ba(1), and one P(1) atom. In the second O site, O(2) is bonded in a 2-coordinate geometry to one Na(2), one Ba(1), and one P(1) atom.
Na3Ba(PO4)2 crystallizes in the trigonal P-3m1 space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 1-coordinate geometry to one O(1) atom. The Na(1)-O(1) bond length is 2.39 Å. In the second Na site, Na(2) is bonded to six equivalent O(2) atoms to form NaO6 octahedra that share corners with six equivalent P(1)O4 tetrahedra and faces with two equivalent Ba(1)O12 cuboctahedra. All Na(2)-O(2) bond lengths are 2.30 Å. Ba(1) is bonded to six equivalent O(1) and six equivalent O(2) atoms to form distorted BaO12 cuboctahedra that share edges with six equivalent Ba(1)O12 cuboctahedra, edges with six equivalent P(1)O4 tetrahedra, and faces with two equivalent Na(2)O6 octahedra. All Ba(1)-O(1) bond lengths are 3.25 Å. All Ba(1)-O(2) bond lengths are 2.78 Å. P(1) is bonded to one O(1) and three equivalent O(2) atoms to form PO4 tetrahedra that share corners with three equivalent Na(2)O6 octahedra and edges with three equivalent Ba(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles are 18°. The P(1)-O(1) bond length is 1.55 Å. All P(1)-O(2) bond lengths are 1.55 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded in a distorted linear geometry to one Na(1), three equivalent Ba(1), and one P(1) atom. In the second O site, O(2) is bonded in a 2-coordinate geometry to one Na(2), one Ba(1), and one P(1) atom.