Materials Data on K2Fe2SeS3 by Materials Project
K2Fe2SeS3 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are two inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a 1-coordinate geometry to one Fe3+, two equivalent Se2-, and one S2- atom. The K–Fe bond length is 2.32 Å. There are one shorter (3.18 Å) and one longer (3.68 Å) K–Se bond lengths. The K–S bond length is 3.40 Å. In the second K1+ site, K1+ is bonded in a 1-coordinate geometry to two Fe3+, one Se2-, and two equivalent S2- atoms. There are one shorter (2.28 Å) and one longer (2.81 Å) K–Fe bond lengths. The K–Se bond length is 3.27 Å. There are one shorter (3.05 Å) and one longer (3.80 Å) K–S bond lengths. There are two inequivalent Fe3+ sites. In the first Fe3+ site, Fe3+ is bonded in a 4-coordinate geometry to two K1+ and two S2- atoms. There is one shorter (1.71 Å) and one longer (1.89 Å) Fe–S bond length. In the second Fe3+ site, Fe3+ is bonded in a 3-coordinate geometry to one K1+ and three S2- atoms. There are a spread of Fe–S bond distances ranging from 1.73–3.03 Å. Se2- is bonded in a 3-coordinate geometry to three K1+ atoms. There are three inequivalent S2- sites. In the first S2- site, S2- is bonded in a distorted water-like geometry to two Fe3+ atoms. In the second S2- site, S2- is bonded in a 2-coordinate geometry to three K1+ and one Fe3+ atom. In the third S2- site, S2- is bonded in a distorted L-shaped geometry to two Fe3+ atoms.