Materials Data on KAg3Se2 by Materials Project
KAg3Se2 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. K1+ is bonded to seven Se2- atoms to form a mixture of distorted edge and face-sharing KSe7 pentagonal bipyramids. There are a spread of K–Se bond distances ranging from 3.41–3.72 Å. There are three inequivalent Ag1+ sites. In the first Ag1+ site, Ag1+ is bonded in a distorted trigonal planar geometry to three Se2- atoms. There are two shorter (2.71 Å) and one longer (2.77 Å) Ag–Se bond lengths. In the second Ag1+ site, Ag1+ is bonded in a distorted bent 120 degrees geometry to four Se2- atoms. There are a spread of Ag–Se bond distances ranging from 2.64–3.22 Å. In the third Ag1+ site, Ag1+ is bonded in a distorted trigonal non-coplanar geometry to three Se2- atoms. There are one shorter (2.63 Å) and two longer (2.77 Å) Ag–Se bond lengths. There are two inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 6-coordinate geometry to four equivalent K1+ and four Ag1+ atoms. In the second Se2- site, Se2- is bonded in a 9-coordinate geometry to three equivalent K1+ and six Ag1+ atoms.