SrCaGdBiO6 crystallizes in the orthorhombic Cccm space group. Sr(1) is bonded in a distorted body-centered cubic geometry to four equivalent O(1) and four equivalent O(2) atoms. Ca(1) is bonded in a distorted body-centered cubic geometry to four equivalent O(1) and four equivalent O(3) atoms. Gd(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form GdO6 octahedra that share corners with six equivalent Bi(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-35°. Bi(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form BiO6 octahedra that share corners with six equivalent Gd(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-35°. There are three inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Sr(1), two equivalent Ca(1), one Gd(1), and one Bi(1) atom to form distorted OSr2Ca2GdBi octahedra that share corners with six equivalent O(1)Sr2Ca2GdBi octahedra, corners with four equivalent O(3)Ca2GdBi tetrahedra, corners with four equivalent O(2)Sr2GdBi tetrahedra, edges with four equivalent O(1)Sr2Ca2GdBi octahedra, edges with four equivalent O(3)Ca2GdBi tetrahedra, and edges with four equivalent O(2)Sr2GdBi tetrahedra. The corner-sharing octahedral tilt angles range from 0-2°. In the second O site, O(2) is bonded to two equivalent Sr(1), one Gd(1), and one Bi(1) atom to form distorted OSr2GdBi tetrahedra that share corners with four equivalent O(1)Sr2Ca2GdBi octahedra, corners with four equivalent O(3)Ca2GdBi tetrahedra, corners with six equivalent O(2)Sr2GdBi tetrahedra, edges with four equivalent O(1)Sr2Ca2GdBi octahedra, and  an edgeedge with one O(2)Sr2GdBi tetrahedra. The corner-sharing octahedral tilt angles range from 66-67°. In the third O site, O(3) is bonded to two equivalent Ca(1), one Gd(1), and one Bi(1) atom to form distorted OCa2GdBi tetrahedra that share corners with four equivalent O(1)Sr2Ca2GdBi octahedra, corners with four equivalent O(2)Sr2GdBi tetrahedra, corners with six equivalent O(3)Ca2GdBi tetrahedra, edges with four equivalent O(1)Sr2Ca2GdBi octahedra, and  an edgeedge with one O(3)Ca2GdBi tetrahedra. The corner-sharing octahedral tilt angles range from 67-68°.
SrCaGdBiO6 crystallizes in the orthorhombic Cccm space group. Sr(1) is bonded in a distorted body-centered cubic geometry to four equivalent O(1) and four equivalent O(2) atoms. All Sr(1)-O(1) bond lengths are 2.98 Å. All Sr(1)-O(2) bond lengths are 2.62 Å. Ca(1) is bonded in a distorted body-centered cubic geometry to four equivalent O(1) and four equivalent O(3) atoms. All Ca(1)-O(1) bond lengths are 2.98 Å. All Ca(1)-O(3) bond lengths are 2.59 Å. Gd(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form GdO6 octahedra that share corners with six equivalent Bi(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-35°. Both Gd(1)-O(1) bond lengths are 2.22 Å. Both Gd(1)-O(2) bond lengths are 2.27 Å. Both Gd(1)-O(3) bond lengths are 2.30 Å. Bi(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form BiO6 octahedra that share corners with six equivalent Gd(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-35°. Both Bi(1)-O(1) bond lengths are 2.11 Å. Both Bi(1)-O(2) bond lengths are 2.13 Å. Both Bi(1)-O(3) bond lengths are 2.15 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Sr(1), two equivalent Ca(1), one Gd(1), and one Bi(1) atom to form distorted OSr2Ca2GdBi octahedra that share corners with six equivalent O(1)Sr2Ca2GdBi octahedra, corners with four equivalent O(3)Ca2GdBi tetrahedra, corners with four equivalent O(2)Sr2GdBi tetrahedra, edges with four equivalent O(1)Sr2Ca2GdBi octahedra, edges with four equivalent O(3)Ca2GdBi tetrahedra, and edges with four equivalent O(2)Sr2GdBi tetrahedra. The corner-sharing octahedral tilt angles range from 0-2°. In the second O site, O(2) is bonded to two equivalent Sr(1), one Gd(1), and one Bi(1) atom to form distorted OSr2GdBi tetrahedra that share corners with four equivalent O(1)Sr2Ca2GdBi octahedra, corners with four equivalent O(3)Ca2GdBi tetrahedra, corners with six equivalent O(2)Sr2GdBi tetrahedra, edges with four equivalent O(1)Sr2Ca2GdBi octahedra, and  an edgeedge with one O(2)Sr2GdBi tetrahedra. The corner-sharing octahedral tilt angles range from 66-67°. In the third O site, O(3) is bonded to two equivalent Ca(1), one Gd(1), and one Bi(1) atom to form distorted OCa2GdBi tetrahedra that share corners with four equivalent O(1)Sr2Ca2GdBi octahedra, corners with four equivalent O(2)Sr2GdBi tetrahedra, corners with six equivalent O(3)Ca2GdBi tetrahedra, edges with four equivalent O(1)Sr2Ca2GdBi octahedra, and  an edgeedge with one O(3)Ca2GdBi tetrahedra. The corner-sharing octahedral tilt angles range from 67-68°.