Materials Data on Ca2Mg3Si by Materials Project

Abstract

Ca2Mg3Si crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Ca is bonded in a 12-coordinate geometry to four equivalent Ca, nine equivalent Mg, and three equivalent Si atoms. There are one shorter (3.62 Å) and three longer (3.67 Å) Ca–Ca bond lengths. There are three shorter (3.41 Å) and six longer (3.53 Å) Ca–Mg bond lengths. All Ca–Si bond lengths are 3.54 Å. Mg is bonded to six equivalent Ca, four equivalent Mg, and two equivalent Si atoms to form distorted MgCa6Mg4Si2 cuboctahedra that share corners with four equivalent SiCa6Mg6 cuboctahedra, corners with fourteen equivalent MgCa6Mg4Si2 cuboctahedra, edges with six equivalent MgCa6Mg4Si2 cuboctahedra, faces with six equivalent SiCa6Mg6 cuboctahedra, and faces with twelve equivalent MgCa6Mg4Si2 cuboctahedra. There are two shorter (3.00 Å) and two longer (3.06 Å) Mg–Mg bond lengths. Both Mg–Si bond lengths are 2.93 Å. Si is bonded to six equivalent Ca and six equivalent Mg atoms to form distorted SiCa6Mg6 cuboctahedra that share corners with twelve equivalent MgCa6Mg4Si2 cuboctahedra, edges with six equivalent SiCa6Mg6 cuboctahedra, faces with two equivalent SiCa6Mg6 cuboctahedra, and faces with eighteen equivalent MgCa6Mg4Si2 cuboctahedra.