Na2TbO3 is Caswellsilverite-like structured and crystallizes in the orthorhombic Immm space group. Na(1) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form NaO6 octahedra that share corners with two equivalent Tb(1)O6 octahedra, corners with four equivalent Na(1)O6 octahedra, edges with five equivalent Tb(1)O6 octahedra, and edges with seven equivalent Na(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-16°. Tb(1) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form TbO6 octahedra that share corners with two equivalent Tb(1)O6 octahedra, corners with four equivalent Na(1)O6 octahedra, edges with two equivalent Tb(1)O6 octahedra, and edges with ten equivalent Na(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-6°. There are two inequivalent O sites. In the first O site, O(1) is bonded to four equivalent Na(1) 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 0-1°. In the second O site, O(2) is bonded to four equivalent Na(1) 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 0-16°.
Na2TbO3 is Caswellsilverite-like structured and crystallizes in the orthorhombic Immm space group. Na(1) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form NaO6 octahedra that share corners with two equivalent Tb(1)O6 octahedra, corners with four equivalent Na(1)O6 octahedra, edges with five equivalent Tb(1)O6 octahedra, and edges with seven equivalent Na(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-16°. Both Na(1)-O(1) bond lengths are 2.52 Å. There are two shorter (2.36 Å) and two longer (2.56 Å) Na(1)-O(2) bond lengths. Tb(1) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form TbO6 octahedra that share corners with two equivalent Tb(1)O6 octahedra, corners with four equivalent Na(1)O6 octahedra, edges with two equivalent Tb(1)O6 octahedra, and edges with ten equivalent Na(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-6°. Both Tb(1)-O(1) bond lengths are 2.34 Å. All Tb(1)-O(2) bond lengths are 2.30 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded to four equivalent Na(1) 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 0-1°. In the second O site, O(2) is bonded to four equivalent Na(1) 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 0-16°.