Mg2Ta4O9 is Ilmenite-like structured and crystallizes in the trigonal P-3c1 space group. Mg(1) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form MgO6 octahedra that share corners with three equivalent Ta(2)O6 octahedra, corners with six equivalent Ta(1)O6 octahedra, edges with three equivalent Ta(2)O6 octahedra, and  a faceface with one Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 48-54°. There are two inequivalent Ta sites. In the first Ta site, Ta(1) is bonded to six equivalent O(1) atoms to form TaO6 octahedra that share corners with three equivalent Ta(2)O6 octahedra, corners with six equivalent Mg(1)O6 octahedra, edges with three equivalent Ta(1)O6 octahedra, and  a faceface with one Ta(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 48-54°. In the second Ta site, Ta(2) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form TaO6 octahedra that share corners with three equivalent Mg(1)O6 octahedra, corners with three equivalent Ta(1)O6 octahedra, corners with three equivalent Ta(2)O6 octahedra, edges with three equivalent Mg(1)O6 octahedra, and  a faceface with one Ta(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 48-57°. There are two inequivalent O sites. In the first O site, O(1) is bonded in a distorted rectangular see-saw-like geometry to one Mg(1), one Ta(2), and two equivalent Ta(1) atoms. In the second O site, O(2) is bonded to two equivalent Mg(1) and two equivalent Ta(2) atoms to form a mixture of distorted edge and corner-sharing OMg2Ta2 trigonal pyramids.
Mg2Ta4O9 is Ilmenite-like structured and crystallizes in the trigonal P-3c1 space group. Mg(1) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form MgO6 octahedra that share corners with three equivalent Ta(2)O6 octahedra, corners with six equivalent Ta(1)O6 octahedra, edges with three equivalent Ta(2)O6 octahedra, and  a faceface with one Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 48-54°. All Mg(1)-O(1) bond lengths are 1.99 Å. All Mg(1)-O(2) bond lengths are 2.16 Å. There are two inequivalent Ta sites. In the first Ta site, Ta(1) is bonded to six equivalent O(1) atoms to form TaO6 octahedra that share corners with three equivalent Ta(2)O6 octahedra, corners with six equivalent Mg(1)O6 octahedra, edges with three equivalent Ta(1)O6 octahedra, and  a faceface with one Ta(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 48-54°. There are three shorter (2.11 Å) and three longer (2.19 Å) Ta(1)-O(1) bond lengths. In the second Ta site, Ta(2) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form TaO6 octahedra that share corners with three equivalent Mg(1)O6 octahedra, corners with three equivalent Ta(1)O6 octahedra, corners with three equivalent Ta(2)O6 octahedra, edges with three equivalent Mg(1)O6 octahedra, and  a faceface with one Ta(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 48-57°. All Ta(2)-O(1) bond lengths are 2.14 Å. All Ta(2)-O(2) bond lengths are 2.06 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded in a distorted rectangular see-saw-like geometry to one Mg(1), one Ta(2), and two equivalent Ta(1) atoms. In the second O site, O(2) is bonded to two equivalent Mg(1) and two equivalent Ta(2) atoms to form a mixture of distorted edge and corner-sharing OMg2Ta2 trigonal pyramids.