Materials Data on KNa4GeAs3 by Materials Project

Abstract

KNa4GeAs3 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. K1+ is bonded to five As3- atoms to form distorted KAs5 trigonal bipyramids that share a cornercorner with one NaAs4 tetrahedra, edges with two equivalent NaAs4 tetrahedra, and edges with four equivalent KAs5 trigonal bipyramids. There are a spread of K–As bond distances ranging from 3.40–3.47 Å. There are four inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded in a 5-coordinate geometry to five As3- atoms. There are a spread of Na–As bond distances ranging from 3.01–3.32 Å. In the second Na1+ site, Na1+ is bonded to four As3- atoms to form NaAs4 tetrahedra that share corners with two equivalent NaAs4 tetrahedra, a cornercorner with one KAs5 trigonal bipyramid, and edges with two equivalent KAs5 trigonal bipyramids. There are a spread of Na–As bond distances ranging from 2.96–3.08 Å. In the third Na1+ site, Na1+ is bonded in a 3-coordinate geometry to five As3- atoms. There are a spread of Na–As bond distances ranging from 2.99–3.48 Å. In the fourth Na1+ site, Na1+ is bonded in a 5-coordinate geometry to five As3- atoms. There are a spread of Na–As bond distances ranging from 3.12–3.37 Å. Ge4+ is bonded in a trigonal planar geometry to three As3- atoms. There are a spread of Ge–As bond distances ranging from 2.36–2.39 Å. There are three inequivalent As3- sites. In the first As3- site, As3- is bonded in a 9-coordinate geometry to two equivalent K1+, six Na1+, and one Ge4+ atom. In the second As3- site, As3- is bonded in a 2-coordinate geometry to three equivalent K1+, five Na1+, and one Ge4+ atom. In the third As3- site, As3- is bonded in a 9-coordinate geometry to eight Na1+ and one Ge4+ atom.