KCa3 is beta Cu3Ti-like structured and crystallizes in the tetragonal I4/mmm space group. K(1) is bonded to four equivalent Ca(2) and eight equivalent Ca(1) atoms to form KCa12 cuboctahedra that share corners with four equivalent K(1)Ca12 cuboctahedra, corners with eight equivalent Ca(2)K4Ca8 cuboctahedra, edges with eight equivalent K(1)Ca12 cuboctahedra, edges with sixteen equivalent Ca(1)K4Ca8 cuboctahedra, faces with four equivalent K(1)Ca12 cuboctahedra, faces with six equivalent Ca(2)K4Ca8 cuboctahedra, and faces with eight equivalent Ca(1)K4Ca8 cuboctahedra. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to four equivalent K(1), four equivalent Ca(1), and four equivalent Ca(2) atoms to form CaK4Ca8 cuboctahedra that share corners with twelve equivalent Ca(1)K4Ca8 cuboctahedra, edges with eight equivalent K(1)Ca12 cuboctahedra, edges with eight equivalent Ca(1)K4Ca8 cuboctahedra, edges with eight equivalent Ca(2)K4Ca8 cuboctahedra, faces with four equivalent K(1)Ca12 cuboctahedra, faces with four equivalent Ca(2)K4Ca8 cuboctahedra, and faces with ten equivalent Ca(1)K4Ca8 cuboctahedra. In the second Ca site, Ca(2) is bonded to four equivalent K(1) and eight equivalent Ca(1) atoms to form CaK4Ca8 cuboctahedra that share corners with four equivalent Ca(2)K4Ca8 cuboctahedra, corners with eight equivalent K(1)Ca12 cuboctahedra, edges with eight equivalent Ca(2)K4Ca8 cuboctahedra, edges with sixteen equivalent Ca(1)K4Ca8 cuboctahedra, faces with four equivalent Ca(2)K4Ca8 cuboctahedra, faces with six equivalent K(1)Ca12 cuboctahedra, and faces with eight equivalent Ca(1)K4Ca8 cuboctahedra.
KCa3 is beta Cu3Ti-like structured and crystallizes in the tetragonal I4/mmm space group. K(1) is bonded to four equivalent Ca(2) and eight equivalent Ca(1) atoms to form KCa12 cuboctahedra that share corners with four equivalent K(1)Ca12 cuboctahedra, corners with eight equivalent Ca(2)K4Ca8 cuboctahedra, edges with eight equivalent K(1)Ca12 cuboctahedra, edges with sixteen equivalent Ca(1)K4Ca8 cuboctahedra, faces with four equivalent K(1)Ca12 cuboctahedra, faces with six equivalent Ca(2)K4Ca8 cuboctahedra, and faces with eight equivalent Ca(1)K4Ca8 cuboctahedra. All K(1)-Ca(2) bond lengths are 4.03 Å. All K(1)-Ca(1) bond lengths are 4.08 Å. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to four equivalent K(1), four equivalent Ca(1), and four equivalent Ca(2) atoms to form CaK4Ca8 cuboctahedra that share corners with twelve equivalent Ca(1)K4Ca8 cuboctahedra, edges with eight equivalent K(1)Ca12 cuboctahedra, edges with eight equivalent Ca(1)K4Ca8 cuboctahedra, edges with eight equivalent Ca(2)K4Ca8 cuboctahedra, faces with four equivalent K(1)Ca12 cuboctahedra, faces with four equivalent Ca(2)K4Ca8 cuboctahedra, and faces with ten equivalent Ca(1)K4Ca8 cuboctahedra. All Ca(1)-Ca(1) bond lengths are 4.03 Å. All Ca(1)-Ca(2) bond lengths are 4.08 Å. In the second Ca site, Ca(2) is bonded to four equivalent K(1) and eight equivalent Ca(1) atoms to form CaK4Ca8 cuboctahedra that share corners with four equivalent Ca(2)K4Ca8 cuboctahedra, corners with eight equivalent K(1)Ca12 cuboctahedra, edges with eight equivalent Ca(2)K4Ca8 cuboctahedra, edges with sixteen equivalent Ca(1)K4Ca8 cuboctahedra, faces with four equivalent Ca(2)K4Ca8 cuboctahedra, faces with six equivalent K(1)Ca12 cuboctahedra, and faces with eight equivalent Ca(1)K4Ca8 cuboctahedra.