Materials Data on LiFeAs by Materials Project

Abstract

LiFeAs crystallizes in the trigonal P-3m1 space group. The structure is three-dimensional. there are two inequivalent Li1+ sites. In the first Li1+ site, Li1+ is bonded to five As3- atoms to form distorted LiAs5 trigonal bipyramids that share corners with two equivalent FeAs5 trigonal bipyramids, corners with six equivalent LiAs5 trigonal bipyramids, edges with three equivalent LiAs5 trigonal bipyramids, and edges with three equivalent FeAs5 trigonal bipyramids. There are a spread of Li–As bond distances ranging from 2.37–2.66 Å. In the second Li1+ site, Li1+ is bonded in a 6-coordinate geometry to one Fe2+ and six As3- atoms. The Li–Fe bond length is 2.57 Å. There are three shorter (2.73 Å) and three longer (2.79 Å) Li–As bond lengths. There are three inequivalent Fe2+ sites. In the first Fe2+ site, Fe2+ is bonded in a distorted body-centered cubic geometry to two equivalent Li1+ and six equivalent As3- atoms. All Fe–As bond lengths are 2.63 Å. In the second Fe2+ site, Fe2+ is bonded to five As3- atoms to form distorted FeAs5 trigonal bipyramids that share corners with two equivalent LiAs5 trigonal bipyramids, corners with six equivalent FeAs5 trigonal bipyramids, edges with three equivalent LiAs5 trigonal bipyramids, and edges with three equivalent FeAs5 trigonal bipyramids. There are a spread of Fe–As bond distances ranging from 2.36–2.63 Å. In the third Fe2+ site, Fe2+ is bonded in a 8-coordinate geometry to six equivalent As3- atoms. All Fe–As bond lengths are 2.60 Å. There are two inequivalent As3- sites. In the first As3- site, As3- is bonded in a 11-coordinate geometry to four Li1+ and seven Fe2+ atoms. In the second As3- site, As3- is bonded in a 11-coordinate geometry to seven Li1+ and four Fe2+ atoms.