CaYb2O4 crystallizes in the orthorhombic Pnma space group. Ca(1) is bonded in a 8-coordinate geometry to two equivalent O(1), two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms. There are two inequivalent Yb sites. In the first Yb site, Yb(1) is bonded in a 7-coordinate geometry to one O(2), one O(3), two equivalent O(4), and three equivalent O(1) atoms. In the second Yb site, Yb(2) is bonded to one O(4), two equivalent O(2), and three equivalent O(3) atoms to form edge-sharing YbO6 octahedra. There are four inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Ca(1) and three equivalent Yb(1) atoms to form distorted OCa2Yb3 trigonal bipyramids that share corners with four equivalent O(3)Ca2Yb4 octahedra, corners with six equivalent O(4)Ca2Yb3 square pyramids, corners with three equivalent O(2)Ca2Yb3 trigonal bipyramids, edges with two equivalent O(4)Ca2Yb3 square pyramids, edges with two equivalent O(2)Ca2Yb3 trigonal bipyramids, edges with four equivalent O(1)Ca2Yb3 trigonal bipyramids, and  a faceface with one O(3)Ca2Yb4 octahedra. The corner-sharing octahedral tilt angles range from 56-63°. In the second O site, O(2) is bonded to two equivalent Ca(1), one Yb(1), and two equivalent Yb(2) atoms to form distorted OCa2Yb3 trigonal bipyramids that share corners with five equivalent O(3)Ca2Yb4 octahedra, corners with three equivalent O(1)Ca2Yb3 trigonal bipyramids, corners with four equivalent O(2)Ca2Yb3 trigonal bipyramids, edges with three equivalent O(3)Ca2Yb4 octahedra, edges with four equivalent O(4)Ca2Yb3 square pyramids, and edges with two equivalent O(1)Ca2Yb3 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 5-49°. In the third O site, O(3) is bonded to two equivalent Ca(1), one Yb(1), and three equivalent Yb(2) atoms to form OCa2Yb4 octahedra that share corners with three equivalent O(4)Ca2Yb3 square pyramids, corners with four equivalent O(1)Ca2Yb3 trigonal bipyramids, corners with five equivalent O(2)Ca2Yb3 trigonal bipyramids, edges with four equivalent O(3)Ca2Yb4 octahedra, edges with three equivalent O(4)Ca2Yb3 square pyramids, edges with three equivalent O(2)Ca2Yb3 trigonal bipyramids, and  a faceface with one O(1)Ca2Yb3 trigonal bipyramid. In the fourth O site, O(4) is bonded to two equivalent Ca(1), one Yb(2), and two equivalent Yb(1) atoms to form distorted OCa2Yb3 square pyramids that share corners with three equivalent O(3)Ca2Yb4 octahedra, corners with six equivalent O(1)Ca2Yb3 trigonal bipyramids, edges with three equivalent O(3)Ca2Yb4 octahedra, edges with two equivalent O(4)Ca2Yb3 square pyramids, edges with two equivalent O(1)Ca2Yb3 trigonal bipyramids, and edges with four equivalent O(2)Ca2Yb3 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 2-30°.
CaYb2O4 crystallizes in the orthorhombic Pnma space group. Ca(1) is bonded in a 8-coordinate geometry to two equivalent O(1), two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms. Both Ca(1)-O(1) bond lengths are 2.40 Å. There is one shorter (2.45 Å) and one longer (2.66 Å) Ca(1)-O(2) bond length. Both Ca(1)-O(3) bond lengths are 2.63 Å. Both Ca(1)-O(4) bond lengths are 2.44 Å. There are two inequivalent Yb sites. In the first Yb site, Yb(1) is bonded in a 7-coordinate geometry to one O(2), one O(3), two equivalent O(4), and three equivalent O(1) atoms. The Yb(1)-O(2) bond length is 2.29 Å. The Yb(1)-O(3) bond length is 2.61 Å. Both Yb(1)-O(4) bond lengths are 2.31 Å. There is one shorter (2.29 Å) and two longer (2.40 Å) Yb(1)-O(1) bond lengths. In the second Yb site, Yb(2) is bonded to one O(4), two equivalent O(2), and three equivalent O(3) atoms to form edge-sharing YbO6 octahedra. The Yb(2)-O(4) bond length is 2.23 Å. Both Yb(2)-O(2) bond lengths are 2.24 Å. There is one shorter (2.38 Å) and two longer (2.40 Å) Yb(2)-O(3) bond lengths. There are four inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Ca(1) and three equivalent Yb(1) atoms to form distorted OCa2Yb3 trigonal bipyramids that share corners with four equivalent O(3)Ca2Yb4 octahedra, corners with six equivalent O(4)Ca2Yb3 square pyramids, corners with three equivalent O(2)Ca2Yb3 trigonal bipyramids, edges with two equivalent O(4)Ca2Yb3 square pyramids, edges with two equivalent O(2)Ca2Yb3 trigonal bipyramids, edges with four equivalent O(1)Ca2Yb3 trigonal bipyramids, and  a faceface with one O(3)Ca2Yb4 octahedra. The corner-sharing octahedral tilt angles range from 56-63°. In the second O site, O(2) is bonded to two equivalent Ca(1), one Yb(1), and two equivalent Yb(2) atoms to form distorted OCa2Yb3 trigonal bipyramids that share corners with five equivalent O(3)Ca2Yb4 octahedra, corners with three equivalent O(1)Ca2Yb3 trigonal bipyramids, corners with four equivalent O(2)Ca2Yb3 trigonal bipyramids, edges with three equivalent O(3)Ca2Yb4 octahedra, edges with four equivalent O(4)Ca2Yb3 square pyramids, and edges with two equivalent O(1)Ca2Yb3 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 5-49°. In the third O site, O(3) is bonded to two equivalent Ca(1), one Yb(1), and three equivalent Yb(2) atoms to form OCa2Yb4 octahedra that share corners with three equivalent O(4)Ca2Yb3 square pyramids, corners with four equivalent O(1)Ca2Yb3 trigonal bipyramids, corners with five equivalent O(2)Ca2Yb3 trigonal bipyramids, edges with four equivalent O(3)Ca2Yb4 octahedra, edges with three equivalent O(4)Ca2Yb3 square pyramids, edges with three equivalent O(2)Ca2Yb3 trigonal bipyramids, and  a faceface with one O(1)Ca2Yb3 trigonal bipyramid. In the fourth O site, O(4) is bonded to two equivalent Ca(1), one Yb(2), and two equivalent Yb(1) atoms to form distorted OCa2Yb3 square pyramids that share corners with three equivalent O(3)Ca2Yb4 octahedra, corners with six equivalent O(1)Ca2Yb3 trigonal bipyramids, edges with three equivalent O(3)Ca2Yb4 octahedra, edges with two equivalent O(4)Ca2Yb3 square pyramids, edges with two equivalent O(1)Ca2Yb3 trigonal bipyramids, and edges with four equivalent O(2)Ca2Yb3 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 2-30°.