DOE OSTI2020
Ca14Si19 crystallizes in the trigonal R-3c space group. The structure is three-dimensional. there are five inequivalent Ca2+ sites. In the first Ca2+ site, Ca2+ is bonded in a 9-coordinate geometry to nine Si+1.47- atoms. There are a spread of Ca–Si bond distances ranging from 2.97–3.41 Å. In the second Ca2+ site, Ca2+ is bonded in a 1-coordinate geometry to nine Si+1.47- atoms. There are a spread of Ca–Si bond distances ranging from 2.90–3.15 Å. In the third Ca2+ site, Ca2+ is bonded in a 10-coordinate geometry to ten Si+1.47- atoms. There are a spread of Ca–Si bond distances ranging from 2.95–3.31 Å. In the fourth Ca2+ site, Ca2+ is bonded in a 6-coordinate geometry to nine Si+1.47- atoms. There are a spread of Ca–Si bond distances ranging from 3.11–3.47 Å. In the fifth Ca2+ site, Ca2+ is bonded in an octahedral geometry to six equivalent Si+1.47- atoms. All Ca–Si bond lengths are 3.23 Å. There are five inequivalent Si+1.47- sites. In the first Si+1.47- site, Si+1.47- is bonded in a 9-coordinate geometry to seven Ca2+ and two Si+1.47- atoms. There are one shorter (2.35 Å) and one longer (2.54 Å) Si–Si bond lengths. In the second Si+1.47- site, Si+1.47- is bonded in a 9-coordinate geometry to seven Ca2+ and two equivalent Si+1.47- atoms. Both Si–Si bond lengths are 2.40 Å. In the third Si+1.47- site, Si+1.47- is bonded in a 10-coordinate geometry to seven Ca2+ and three equivalent Si+1.47- atoms. In the fourth Si+1.47- site, Si+1.47- is bonded in a 9-coordinate geometry to six Ca2+ and three Si+1.47- atoms. The Si–Si bond length is 2.39 Å. In the fifth Si+1.47- site, Si+1.47- is bonded in a 9-coordinate geometry to six Ca2+ and three equivalent Si+1.47- atoms.