K3Nb is alpha bismuth trifluoride structured and crystallizes in the tetragonal I4/mmm space group. There are two inequivalent K sites. In the first K site, K(1) is bonded to four equivalent K(2) and four equivalent Nb(1) atoms to form distorted KK4Nb4 cuboctahedra that share corners with eight equivalent K(1)K4Nb4 cuboctahedra, corners with eight equivalent K(2)K8Nb4 cuboctahedra, corners with eight equivalent Nb(1)K12 cuboctahedra, edges with four equivalent K(2)K8Nb4 cuboctahedra, edges with four equivalent Nb(1)K12 cuboctahedra, edges with twelve equivalent K(1)K4Nb4 cuboctahedra, and faces with six equivalent K(1)K4Nb4 cuboctahedra. In the second K site, K(2) is bonded to eight equivalent K(1) and four equivalent Nb(1) atoms to form KK8Nb4 cuboctahedra that share corners with four equivalent K(2)K8Nb4 cuboctahedra, corners with eight equivalent Nb(1)K12 cuboctahedra, corners with sixteen equivalent K(1)K4Nb4 cuboctahedra, edges with eight equivalent K(1)K4Nb4 cuboctahedra, edges with eight equivalent K(2)K8Nb4 cuboctahedra, faces with four equivalent K(2)K8Nb4 cuboctahedra, and faces with six equivalent Nb(1)K12 cuboctahedra. Nb(1) is bonded to four equivalent K(2) and eight equivalent K(1) atoms to form NbK12 cuboctahedra that share corners with four equivalent Nb(1)K12 cuboctahedra, corners with eight equivalent K(2)K8Nb4 cuboctahedra, corners with sixteen equivalent K(1)K4Nb4 cuboctahedra, edges with eight equivalent K(1)K4Nb4 cuboctahedra, edges with eight equivalent Nb(1)K12 cuboctahedra, faces with four equivalent Nb(1)K12 cuboctahedra, and faces with six equivalent K(2)K8Nb4 cuboctahedra.
K3Nb is alpha bismuth trifluoride structured and crystallizes in the tetragonal I4/mmm space group. There are two inequivalent K sites. In the first K site, K(1) is bonded to four equivalent K(2) and four equivalent Nb(1) atoms to form distorted KK4Nb4 cuboctahedra that share corners with eight equivalent K(1)K4Nb4 cuboctahedra, corners with eight equivalent K(2)K8Nb4 cuboctahedra, corners with eight equivalent Nb(1)K12 cuboctahedra, edges with four equivalent K(2)K8Nb4 cuboctahedra, edges with four equivalent Nb(1)K12 cuboctahedra, edges with twelve equivalent K(1)K4Nb4 cuboctahedra, and faces with six equivalent K(1)K4Nb4 cuboctahedra. All K(1)-K(2) bond lengths are 4.05 Å. All K(1)-Nb(1) bond lengths are 4.05 Å. In the second K site, K(2) is bonded to eight equivalent K(1) and four equivalent Nb(1) atoms to form KK8Nb4 cuboctahedra that share corners with four equivalent K(2)K8Nb4 cuboctahedra, corners with eight equivalent Nb(1)K12 cuboctahedra, corners with sixteen equivalent K(1)K4Nb4 cuboctahedra, edges with eight equivalent K(1)K4Nb4 cuboctahedra, edges with eight equivalent K(2)K8Nb4 cuboctahedra, faces with four equivalent K(2)K8Nb4 cuboctahedra, and faces with six equivalent Nb(1)K12 cuboctahedra. All K(2)-Nb(1) bond lengths are 4.19 Å. Nb(1) is bonded to four equivalent K(2) and eight equivalent K(1) atoms to form NbK12 cuboctahedra that share corners with four equivalent Nb(1)K12 cuboctahedra, corners with eight equivalent K(2)K8Nb4 cuboctahedra, corners with sixteen equivalent K(1)K4Nb4 cuboctahedra, edges with eight equivalent K(1)K4Nb4 cuboctahedra, edges with eight equivalent Nb(1)K12 cuboctahedra, faces with four equivalent Nb(1)K12 cuboctahedra, and faces with six equivalent K(2)K8Nb4 cuboctahedra.