CaBi2Ta2O9 crystallizes in the orthorhombic Cmc2_1 space group. Ca(1) is bonded in a 8-coordinate geometry to two equivalent O(2), two equivalent O(3), and four equivalent O(5) atoms. Ta(1) is bonded to one O(1), one O(3), two equivalent O(2), and two equivalent O(5) atoms to form corner-sharing TaO6 octahedra. The corner-sharing octahedral tilt angles range from 25-31°. Bi(1) is bonded in a 6-coordinate geometry to two equivalent O(1) and four equivalent O(4) atoms. There are five inequivalent O sites. In the first O site, O(1) is bonded in a distorted single-bond geometry to one Ta(1) and two equivalent Bi(1) atoms. In the second O site, O(2) is bonded in a distorted T-shaped geometry to one Ca(1) and two equivalent Ta(1) atoms. In the third O site, O(3) is bonded to two equivalent Ca(1) and two equivalent Ta(1) atoms to form a mixture of distorted corner and edge-sharing OCa2Ta2 tetrahedra. In the fourth O site, O(4) is bonded to four equivalent Bi(1) atoms to form a mixture of corner and edge-sharing OBi4 tetrahedra. In the fifth O site, O(5) is bonded to two equivalent Ca(1) and two equivalent Ta(1) atoms to form a mixture of distorted corner and edge-sharing OCa2Ta2 trigonal pyramids.
CaBi2Ta2O9 crystallizes in the orthorhombic Cmc2_1 space group. Ca(1) is bonded in a 8-coordinate geometry to two equivalent O(2), two equivalent O(3), and four equivalent O(5) atoms. Both Ca(1)-O(2) bond lengths are 2.61 Å. There is one shorter (2.38 Å) and one longer (2.41 Å) Ca(1)-O(3) bond length. There are two shorter (2.44 Å) and two longer (2.54 Å) Ca(1)-O(5) bond lengths. Ta(1) is bonded to one O(1), one O(3), two equivalent O(2), and two equivalent O(5) atoms to form corner-sharing TaO6 octahedra. The corner-sharing octahedral tilt angles range from 25-31°. The Ta(1)-O(1) bond length is 1.90 Å. The Ta(1)-O(3) bond length is 2.11 Å. There is one shorter (1.94 Å) and one longer (2.05 Å) Ta(1)-O(2) bond length. There is one shorter (1.96 Å) and one longer (2.11 Å) Ta(1)-O(5) bond length. Bi(1) is bonded in a 6-coordinate geometry to two equivalent O(1) and four equivalent O(4) atoms. There is one shorter (2.47 Å) and one longer (2.55 Å) Bi(1)-O(1) bond length. There are a spread of Bi(1)-O(4) bond distances ranging from 2.20-2.57 Å. There are five inequivalent O sites. In the first O site, O(1) is bonded in a distorted single-bond geometry to one Ta(1) and two equivalent Bi(1) atoms. In the second O site, O(2) is bonded in a distorted T-shaped geometry to one Ca(1) and two equivalent Ta(1) atoms. In the third O site, O(3) is bonded to two equivalent Ca(1) and two equivalent Ta(1) atoms to form a mixture of distorted corner and edge-sharing OCa2Ta2 tetrahedra. In the fourth O site, O(4) is bonded to four equivalent Bi(1) atoms to form a mixture of corner and edge-sharing OBi4 tetrahedra. In the fifth O site, O(5) is bonded to two equivalent Ca(1) and two equivalent Ta(1) atoms to form a mixture of distorted corner and edge-sharing OCa2Ta2 trigonal pyramids.