KMgNbO3 crystallizes in the tetragonal P4/mmm space group. K(1) is bonded to two equivalent Mg(1) and four equivalent O(1) atoms to form KMg2O4 octahedra that share corners with six equivalent K(1)Mg2O4 octahedra, corners with eight equivalent Nb(1)O6 octahedra, and edges with four equivalent K(1)Mg2O4 octahedra. The corner-sharing octahedral tilt angles range from 0-90°. Mg(1) is bonded to two equivalent K(1) and four equivalent O(2) atoms to form distorted MgK2O4 octahedra that share corners with six equivalent Mg(1)K2O4 octahedra, corners with eight equivalent O(1)K4Nb2 octahedra, and edges with four equivalent Nb(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-90°. Nb(1) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form NbO6 octahedra that share corners with six equivalent Nb(1)O6 octahedra, corners with eight equivalent K(1)Mg2O4 octahedra, and edges with four equivalent Mg(1)K2O4 octahedra. The corner-sharing octahedral tilt angles range from 0-90°. There are two inequivalent O sites. In the first O site, O(1) is bonded to four equivalent K(1) and two equivalent Nb(1) atoms to form OK4Nb2 octahedra that share corners with six equivalent O(1)K4Nb2 octahedra, corners with eight equivalent Mg(1)K2O4 octahedra, and edges with four equivalent O(1)K4Nb2 octahedra. The corner-sharing octahedral tilt angles range from 0-90°. In the second O site, O(2) is bonded in a square co-planar geometry to two equivalent Mg(1) and two equivalent Nb(1) atoms.
KMgNbO3 crystallizes in the tetragonal P4/mmm space group. K(1) is bonded to two equivalent Mg(1) and four equivalent O(1) atoms to form KMg2O4 octahedra that share corners with six equivalent K(1)Mg2O4 octahedra, corners with eight equivalent Nb(1)O6 octahedra, and edges with four equivalent K(1)Mg2O4 octahedra. The corner-sharing octahedral tilt angles range from 0-90°. Both K(1)-Mg(1) bond lengths are 2.46 Å. All K(1)-O(1) bond lengths are 2.94 Å. Mg(1) is bonded to two equivalent K(1) and four equivalent O(2) atoms to form distorted MgK2O4 octahedra that share corners with six equivalent Mg(1)K2O4 octahedra, corners with eight equivalent O(1)K4Nb2 octahedra, and edges with four equivalent Nb(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-90°. All Mg(1)-O(2) bond lengths are 2.08 Å. Nb(1) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form NbO6 octahedra that share corners with six equivalent Nb(1)O6 octahedra, corners with eight equivalent K(1)Mg2O4 octahedra, and edges with four equivalent Mg(1)K2O4 octahedra. The corner-sharing octahedral tilt angles range from 0-90°. Both Nb(1)-O(1) bond lengths are 2.46 Å. All Nb(1)-O(2) bond lengths are 2.08 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded to four equivalent K(1) and two equivalent Nb(1) atoms to form OK4Nb2 octahedra that share corners with six equivalent O(1)K4Nb2 octahedra, corners with eight equivalent Mg(1)K2O4 octahedra, and edges with four equivalent O(1)K4Nb2 octahedra. The corner-sharing octahedral tilt angles range from 0-90°. In the second O site, O(2) is bonded in a square co-planar geometry to two equivalent Mg(1) and two equivalent Nb(1) atoms.