Materials Data on Ca2Si by Materials Project
Ca2Si is Cotunnite structured and crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. there are two inequivalent Ca2+ sites. In the first Ca2+ site, Ca2+ is bonded to four equivalent Si4- atoms to form a mixture of corner and edge-sharing CaSi4 tetrahedra. There are three shorter (2.99 Å) and one longer (3.07 Å) Ca–Si bond lengths. In the second Ca2+ site, Ca2+ is bonded in a 5-coordinate geometry to three equivalent Si4- atoms. There are one shorter (3.11 Å) and two longer (3.25 Å) Ca–Si bond lengths. Si4- is bonded in a 9-coordinate geometry to seven Ca2+ atoms.