DOE OSTI2020
SrCaPb6 crystallizes in the tetragonal P4/mmm space group. The structure is three-dimensional. Sr is bonded to twelve Pb atoms to form SrPb12 cuboctahedra that share corners with four equivalent SrPb12 cuboctahedra, corners with eight equivalent CaPb12 cuboctahedra, faces with two equivalent CaPb12 cuboctahedra, and faces with four equivalent SrPb12 cuboctahedra. There are eight shorter (3.56 Å) and four longer (3.59 Å) Sr–Pb bond lengths. Ca is bonded to twelve Pb atoms to form CaPb12 cuboctahedra that share corners with four equivalent CaPb12 cuboctahedra, corners with eight equivalent SrPb12 cuboctahedra, faces with two equivalent SrPb12 cuboctahedra, and faces with four equivalent CaPb12 cuboctahedra. There are eight shorter (3.51 Å) and four longer (3.59 Å) Ca–Pb bond lengths. There are three inequivalent Pb sites. In the first Pb site, Pb is bonded in a distorted rectangular see-saw-like geometry to two equivalent Sr and two equivalent Ca atoms. In the second Pb site, Pb is bonded in a distorted square co-planar geometry to four equivalent Ca atoms. In the third Pb site, Pb is bonded in a square co-planar geometry to four equivalent Sr atoms.