Materials Data on KCeGeSe4 by Materials Project
KCeGeSe4 crystallizes in the monoclinic P2_1 space group. The structure is three-dimensional. K1+ is bonded in a 8-coordinate geometry to eight Se2- atoms. There are a spread of K–Se bond distances ranging from 3.41–3.91 Å. Ce3+ is bonded to seven Se2- atoms to form distorted CeSe7 pentagonal bipyramids that share corners with two equivalent CeSe7 pentagonal bipyramids, a cornercorner with one GeSe4 tetrahedra, edges with two equivalent CeSe7 pentagonal bipyramids, and edges with three equivalent GeSe4 tetrahedra. There are a spread of Ce–Se bond distances ranging from 3.01–3.17 Å. Ge4+ is bonded to four Se2- atoms to form GeSe4 tetrahedra that share a cornercorner with one CeSe7 pentagonal bipyramid and edges with three equivalent CeSe7 pentagonal bipyramids. There are one shorter (2.36 Å) and three longer (2.39 Å) Ge–Se bond lengths. There are four inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 5-coordinate geometry to three equivalent K1+, one Ce3+, and one Ge4+ atom. In the second Se2- site, Se2- is bonded in a 5-coordinate geometry to two equivalent K1+, two equivalent Ce3+, and one Ge4+ atom. In the third Se2- site, Se2- is bonded in a distorted see-saw-like geometry to one K1+, two equivalent Ce3+, and one Ge4+ atom. In the fourth Se2- site, Se2- is bonded in a 5-coordinate geometry to two equivalent K1+, two equivalent Ce3+, and one Ge4+ atom.