Ca2V3O8 crystallizes in the hexagonal P6_3mc space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form distorted CaO6 octahedra that share corners with six equivalent V(1)O6 octahedra, corners with three equivalent Ca(2)O4 tetrahedra, and edges with three equivalent V(1)O6 octahedra. The corner-sharing octahedral tilt angles are 52°. In the second Ca site, Ca(2) is bonded to one O(4) and three equivalent O(2) atoms to form CaO4 tetrahedra that share corners with three equivalent Ca(1)O6 octahedra and corners with nine equivalent V(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 59-75°. V(1) is bonded to one O(3), one O(4), two equivalent O(1), and two equivalent O(2) atoms to form VO6 octahedra that share corners with two equivalent Ca(1)O6 octahedra, corners with three equivalent Ca(2)O4 tetrahedra,  an edgeedge with one Ca(1)O6 octahedra, and edges with four equivalent V(1)O6 octahedra. The corner-sharing octahedral tilt angles are 52°. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Ca(1) and two equivalent V(1) atoms. In the second O site, O(2) is bonded to one Ca(1), one Ca(2), and two equivalent V(1) atoms to form OCa2V2 tetrahedra that share corners with two equivalent O(2)Ca2V2 tetrahedra,  a cornercorner with one O(4)CaV3 trigonal pyramid, edges with two equivalent O(2)Ca2V2 tetrahedra, and  an edgeedge with one O(4)CaV3 trigonal pyramid. In the third O site, O(3) is bonded in a distorted T-shaped geometry to three equivalent V(1) atoms. In the fourth O site, O(4) is bonded to one Ca(2) and three equivalent V(1) atoms to form a mixture of distorted corner and edge-sharing OCaV3 trigonal pyramids.
Ca2V3O8 crystallizes in the hexagonal P6_3mc space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form distorted CaO6 octahedra that share corners with six equivalent V(1)O6 octahedra, corners with three equivalent Ca(2)O4 tetrahedra, and edges with three equivalent V(1)O6 octahedra. The corner-sharing octahedral tilt angles are 52°. All Ca(1)-O(1) bond lengths are 2.32 Å. All Ca(1)-O(2) bond lengths are 2.40 Å. In the second Ca site, Ca(2) is bonded to one O(4) and three equivalent O(2) atoms to form CaO4 tetrahedra that share corners with three equivalent Ca(1)O6 octahedra and corners with nine equivalent V(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 59-75°. The Ca(2)-O(4) bond length is 2.27 Å. All Ca(2)-O(2) bond lengths are 2.17 Å. V(1) is bonded to one O(3), one O(4), two equivalent O(1), and two equivalent O(2) atoms to form VO6 octahedra that share corners with two equivalent Ca(1)O6 octahedra, corners with three equivalent Ca(2)O4 tetrahedra,  an edgeedge with one Ca(1)O6 octahedra, and edges with four equivalent V(1)O6 octahedra. The corner-sharing octahedral tilt angles are 52°. The V(1)-O(3) bond length is 2.00 Å. The V(1)-O(4) bond length is 2.07 Å. Both V(1)-O(1) bond lengths are 1.93 Å. Both V(1)-O(2) bond lengths are 1.99 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Ca(1) and two equivalent V(1) atoms. In the second O site, O(2) is bonded to one Ca(1), one Ca(2), and two equivalent V(1) atoms to form OCa2V2 tetrahedra that share corners with two equivalent O(2)Ca2V2 tetrahedra,  a cornercorner with one O(4)CaV3 trigonal pyramid, edges with two equivalent O(2)Ca2V2 tetrahedra, and  an edgeedge with one O(4)CaV3 trigonal pyramid. In the third O site, O(3) is bonded in a distorted T-shaped geometry to three equivalent V(1) atoms. In the fourth O site, O(4) is bonded to one Ca(2) and three equivalent V(1) atoms to form a mixture of distorted corner and edge-sharing OCaV3 trigonal pyramids.