Sr2TbCu2(BiO4)2 crystallizes in the tetragonal I4/mmm space group. Sr(1) is bonded in a 9-coordinate geometry to one O(2), four equivalent O(1), and four equivalent O(3) atoms. Tb(1) is bonded in a body-centered cubic geometry to eight equivalent O(1) atoms. Cu(1) is bonded to one O(3) and four equivalent O(1) atoms to form distorted corner-sharing CuO5 square pyramids. Bi(1) is bonded in a 6-coordinate geometry to one O(3) and five equivalent O(2) atoms. There are three inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Sr(1), two equivalent Tb(1), and two equivalent Cu(1) atoms to form distorted OSr2Tb2Cu2 octahedra that share corners with two equivalent O(2)SrBi5 octahedra, corners with four equivalent O(3)Sr4CuBi octahedra, corners with eight equivalent O(1)Sr2Tb2Cu2 octahedra, edges with three equivalent O(1)Sr2Tb2Cu2 octahedra, faces with two equivalent O(3)Sr4CuBi octahedra, and faces with four equivalent O(1)Sr2Tb2Cu2 octahedra. The corner-sharing octahedral tilt angles range from 0-67°. In the second O site, O(2) is bonded to one Sr(1) and five equivalent Bi(1) atoms to form distorted OSrBi5 octahedra that share  a cornercorner with one O(3)Sr4CuBi octahedra, corners with four equivalent O(1)Sr2Tb2Cu2 octahedra, corners with four equivalent O(2)SrBi5 octahedra, edges with four equivalent O(3)Sr4CuBi octahedra, and edges with eight equivalent O(2)SrBi5 octahedra. The corner-sharing octahedral tilt angles range from 0-44°. In the third O site, O(3) is bonded to four equivalent Sr(1), one Cu(1), and one Bi(1) atom to form distorted OSr4CuBi octahedra that share  a cornercorner with one O(2)SrBi5 octahedra, corners with four equivalent O(3)Sr4CuBi octahedra, corners with eight equivalent O(1)Sr2Tb2Cu2 octahedra, edges with four equivalent O(3)Sr4CuBi octahedra, edges with four equivalent O(2)SrBi5 octahedra, and faces with four equivalent O(1)Sr2Tb2Cu2 octahedra. The corner-sharing octahedral tilt angles range from 0-50°.
Sr2TbCu2(BiO4)2 crystallizes in the tetragonal I4/mmm space group. Sr(1) is bonded in a 9-coordinate geometry to one O(2), four equivalent O(1), and four equivalent O(3) atoms. The Sr(1)-O(2) bond length is 2.69 Å. All Sr(1)-O(1) bond lengths are 2.76 Å. All Sr(1)-O(3) bond lengths are 2.76 Å. Tb(1) is bonded in a body-centered cubic geometry to eight equivalent O(1) atoms. All Tb(1)-O(1) bond lengths are 2.42 Å. Cu(1) is bonded to one O(3) and four equivalent O(1) atoms to form distorted corner-sharing CuO5 square pyramids. The Cu(1)-O(3) bond length is 2.51 Å. All Cu(1)-O(1) bond lengths are 1.90 Å. Bi(1) is bonded in a 6-coordinate geometry to one O(3) and five equivalent O(2) atoms. The Bi(1)-O(3) bond length is 2.13 Å. There are four shorter (2.69 Å) and one longer (2.87 Å) Bi(1)-O(2) bond length. There are three inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Sr(1), two equivalent Tb(1), and two equivalent Cu(1) atoms to form distorted OSr2Tb2Cu2 octahedra that share corners with two equivalent O(2)SrBi5 octahedra, corners with four equivalent O(3)Sr4CuBi octahedra, corners with eight equivalent O(1)Sr2Tb2Cu2 octahedra, edges with three equivalent O(1)Sr2Tb2Cu2 octahedra, faces with two equivalent O(3)Sr4CuBi octahedra, and faces with four equivalent O(1)Sr2Tb2Cu2 octahedra. The corner-sharing octahedral tilt angles range from 0-67°. In the second O site, O(2) is bonded to one Sr(1) and five equivalent Bi(1) atoms to form distorted OSrBi5 octahedra that share  a cornercorner with one O(3)Sr4CuBi octahedra, corners with four equivalent O(1)Sr2Tb2Cu2 octahedra, corners with four equivalent O(2)SrBi5 octahedra, edges with four equivalent O(3)Sr4CuBi octahedra, and edges with eight equivalent O(2)SrBi5 octahedra. The corner-sharing octahedral tilt angles range from 0-44°. In the third O site, O(3) is bonded to four equivalent Sr(1), one Cu(1), and one Bi(1) atom to form distorted OSr4CuBi octahedra that share  a cornercorner with one O(2)SrBi5 octahedra, corners with four equivalent O(3)Sr4CuBi octahedra, corners with eight equivalent O(1)Sr2Tb2Cu2 octahedra, edges with four equivalent O(3)Sr4CuBi octahedra, edges with four equivalent O(2)SrBi5 octahedra, and faces with four equivalent O(1)Sr2Tb2Cu2 octahedra. The corner-sharing octahedral tilt angles range from 0-50°.