Na2TbO3 is Caswellsilverite-like structured and crystallizes in the monoclinic C2/m space group. There are three inequivalent Na sites. In the first Na site, Na(1) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form NaO6 octahedra that share corners with two equivalent Na(3)O6 octahedra, corners with four equivalent Tb(1)O6 octahedra, edges with two equivalent Na(3)O6 octahedra, edges with four equivalent Tb(1)O6 octahedra, and edges with six equivalent Na(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 8-10°. In the second Na site, Na(2) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form NaO6 octahedra that share corners with two equivalent Na(3)O6 octahedra, corners with four equivalent Tb(1)O6 octahedra, edges with two equivalent Na(3)O6 octahedra, edges with three equivalent Na(1)O6 octahedra, edges with three equivalent Na(2)O6 octahedra, and edges with four equivalent Tb(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 8-10°. In the third Na site, Na(3) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form NaO6 octahedra that share corners with two equivalent Na(1)O6 octahedra, corners with four equivalent Na(2)O6 octahedra, edges with two equivalent Na(1)O6 octahedra, edges with four equivalent Na(2)O6 octahedra, and edges with six equivalent Tb(1)O6 octahedra. The corner-sharing octahedral tilt angles are 10°. Tb(1) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form TbO6 octahedra that share corners with two equivalent Na(1)O6 octahedra, corners with four equivalent Na(2)O6 octahedra, edges with two equivalent Na(1)O6 octahedra, edges with three equivalent Na(3)O6 octahedra, edges with three equivalent Tb(1)O6 octahedra, and edges with four equivalent Na(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 8-10°. There are two inequivalent O sites. In the first O site, O(1) is bonded to one Na(1), one Na(3), two equivalent Na(2), and two equivalent Tb(1) atoms to form a mixture of corner and edge-sharing ONa4Tb2 octahedra. The corner-sharing octahedral tilt angles range from 0-10°. In the second O site, O(2) is bonded to one Na(1), one Na(3), two equivalent Na(2), and two equivalent Tb(1) atoms to form a mixture of corner and edge-sharing ONa4Tb2 octahedra. The corner-sharing octahedral tilt angles range from 0-7°.
Na2TbO3 is Caswellsilverite-like structured and crystallizes in the monoclinic C2/m space group. There are three inequivalent Na sites. In the first Na site, Na(1) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form NaO6 octahedra that share corners with two equivalent Na(3)O6 octahedra, corners with four equivalent Tb(1)O6 octahedra, edges with two equivalent Na(3)O6 octahedra, edges with four equivalent Tb(1)O6 octahedra, and edges with six equivalent Na(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 8-10°. Both Na(1)-O(2) bond lengths are 2.39 Å. All Na(1)-O(1) bond lengths are 2.60 Å. In the second Na site, Na(2) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form NaO6 octahedra that share corners with two equivalent Na(3)O6 octahedra, corners with four equivalent Tb(1)O6 octahedra, edges with two equivalent Na(3)O6 octahedra, edges with three equivalent Na(1)O6 octahedra, edges with three equivalent Na(2)O6 octahedra, and edges with four equivalent Tb(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 8-10°. Both Na(2)-O(2) bond lengths are 2.53 Å. There are two shorter (2.43 Å) and two longer (2.63 Å) Na(2)-O(1) bond lengths. In the third Na site, Na(3) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form NaO6 octahedra that share corners with two equivalent Na(1)O6 octahedra, corners with four equivalent Na(2)O6 octahedra, edges with two equivalent Na(1)O6 octahedra, edges with four equivalent Na(2)O6 octahedra, and edges with six equivalent Tb(1)O6 octahedra. The corner-sharing octahedral tilt angles are 10°. Both Na(3)-O(2) bond lengths are 2.53 Å. All Na(3)-O(1) bond lengths are 2.50 Å. Tb(1) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form TbO6 octahedra that share corners with two equivalent Na(1)O6 octahedra, corners with four equivalent Na(2)O6 octahedra, edges with two equivalent Na(1)O6 octahedra, edges with three equivalent Na(3)O6 octahedra, edges with three equivalent Tb(1)O6 octahedra, and edges with four equivalent Na(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 8-10°. Both Tb(1)-O(2) bond lengths are 2.28 Å. All Tb(1)-O(1) bond lengths are 2.29 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded to one Na(1), one Na(3), two equivalent Na(2), and two equivalent Tb(1) atoms to form a mixture of corner and edge-sharing ONa4Tb2 octahedra. The corner-sharing octahedral tilt angles range from 0-10°. In the second O site, O(2) is bonded to one Na(1), one Na(3), two equivalent Na(2), and two equivalent Tb(1) atoms to form a mixture of corner and edge-sharing ONa4Tb2 octahedra. The corner-sharing octahedral tilt angles range from 0-7°.