Materials Data on KCa3 by Materials Project

Abstract

KCa3 is beta Cu3Ti-like structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. K is bonded to twelve Ca atoms to form KCa12 cuboctahedra that share corners with four equivalent KCa12 cuboctahedra, corners with eight equivalent CaK4Ca8 cuboctahedra, edges with eight equivalent KCa12 cuboctahedra, edges with sixteen equivalent CaK4Ca8 cuboctahedra, faces with four equivalent KCa12 cuboctahedra, and faces with fourteen CaK4Ca8 cuboctahedra. There are four shorter (4.03 Å) and eight longer (4.08 Å) K–Ca bond lengths. There are two inequivalent Ca sites. In the first Ca site, Ca is bonded to four equivalent K and eight Ca atoms to form CaK4Ca8 cuboctahedra that share corners with twelve equivalent CaK4Ca8 cuboctahedra, edges with eight equivalent KCa12 cuboctahedra, edges with sixteen CaK4Ca8 cuboctahedra, faces with four equivalent KCa12 cuboctahedra, and faces with fourteen CaK4Ca8 cuboctahedra. There are four shorter (4.03 Å) and four longer (4.08 Å) Ca–Ca bond lengths. In the second Ca site, Ca is bonded to four equivalent K and eight equivalent Ca atoms to form CaK4Ca8 cuboctahedra that share corners with four equivalent CaK4Ca8 cuboctahedra, corners with eight equivalent KCa12 cuboctahedra, edges with twenty-four CaK4Ca8 cuboctahedra, faces with six equivalent KCa12 cuboctahedra, and faces with twelve CaK4Ca8 cuboctahedra.