Materials Data on Na3Ca by Materials Project

Abstract

Na3Ca is beta Cu3Ti-like structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. there are three inequivalent Na sites. In the first Na site, Na is bonded to eight Na and four equivalent Ca atoms to form NaNa8Ca4 cuboctahedra that share corners with four equivalent CaNa12 cuboctahedra, corners with fourteen NaNa8Ca4 cuboctahedra, edges with six equivalent CaNa12 cuboctahedra, edges with twelve NaNa8Ca4 cuboctahedra, faces with four equivalent CaNa12 cuboctahedra, and faces with sixteen NaNa8Ca4 cuboctahedra. There are a spread of Na–Na bond distances ranging from 3.68–3.93 Å. There are two shorter (3.76 Å) and two longer (3.82 Å) Na–Ca bond lengths. In the second Na site, Na is bonded to eight Na and four equivalent Ca atoms to form NaNa8Ca4 cuboctahedra that share corners with four equivalent CaNa12 cuboctahedra, corners with fourteen NaNa8Ca4 cuboctahedra, edges with six equivalent CaNa12 cuboctahedra, edges with twelve NaNa8Ca4 cuboctahedra, faces with four equivalent CaNa12 cuboctahedra, and faces with sixteen NaNa8Ca4 cuboctahedra. There are one shorter (3.70 Å) and one longer (3.93 Å) Na–Na bond lengths. There are two shorter (3.76 Å) and two longer (3.82 Å) Na–Ca bond lengths. In the third Na site, Na is bonded to eight Na and four equivalent Ca atoms to form NaNa8Ca4 cuboctahedra that share corners with four equivalent CaNa12 cuboctahedra, corners with fourteen NaNa8Ca4 cuboctahedra, edges with six equivalent CaNa12 cuboctahedra, edges with twelve NaNa8Ca4 cuboctahedra, faces with four equivalent CaNa12 cuboctahedra, and faces with sixteen NaNa8Ca4 cuboctahedra. Both Na–Na bond lengths are 3.68 Å. There are two shorter (3.76 Å) and two longer (3.82 Å) Na–Ca bond lengths. Ca is bonded to twelve Na atoms to form CaNa12 cuboctahedra that share corners with six equivalent CaNa12 cuboctahedra, corners with twelve NaNa8Ca4 cuboctahedra, edges with eighteen NaNa8Ca4 cuboctahedra, faces with eight equivalent CaNa12 cuboctahedra, and faces with twelve NaNa8Ca4 cuboctahedra.