Materials Data on K2CdGeO4 by Materials Project

Abstract

K2CdGeO4 crystallizes in the orthorhombic Pca2_1 space group. The structure is three-dimensional. there are four inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a 4-coordinate geometry to four O2- atoms. There are a spread of K–O bond distances ranging from 2.82–2.99 Å. In the second K1+ site, K1+ is bonded to five O2- atoms to form distorted KO5 square pyramids that share corners with three GeO4 tetrahedra, corners with five CdO4 tetrahedra, edges with two equivalent KO5 square pyramids, and an edgeedge with one GeO4 tetrahedra. There are a spread of K–O bond distances ranging from 2.59–2.93 Å. In the third K1+ site, K1+ is bonded in a 4-coordinate geometry to four O2- atoms. There are a spread of K–O bond distances ranging from 2.69–2.83 Å. In the fourth K1+ site, K1+ is bonded to five O2- atoms to form distorted KO5 square pyramids that share corners with three CdO4 tetrahedra, corners with five GeO4 tetrahedra, edges with two equivalent KO5 square pyramids, and an edgeedge with one CdO4 tetrahedra. There are a spread of K–O bond distances ranging from 2.60–2.98 Å. There are two inequivalent Cd2+ sites. In the first Cd2+ site, Cd2+ is bonded to four O2- atoms to form CdO4 tetrahedra that share corners with four KO5 square pyramids and corners with four GeO4 tetrahedra. There are a spread of Cd–O bond distances ranging from 2.20–2.22 Å. In the second Cd2+ site, Cd2+ is bonded to four O2- atoms to form CdO4 tetrahedra that share corners with four KO5 square pyramids, corners with four GeO4 tetrahedra, and an edgeedge with one KO5 square pyramid. There are a spread of Cd–O bond distances ranging from 2.19–2.23 Å. There are two inequivalent Ge4+ sites. In the first Ge4+ site, Ge4+ is bonded to four O2- atoms to form GeO4 tetrahedra that share corners with four KO5 square pyramids and corners with four CdO4 tetrahedra. There is three shorter (1.79 Å) and one longer (1.80 Å) Ge–O bond length. In the second Ge4+ site, Ge4+ is bonded to four O2- atoms to form GeO4 tetrahedra that share corners with four KO5 square pyramids, corners with four CdO4 tetrahedra, and an edgeedge with one KO5 square pyramid. All Ge–O bond lengths are 1.79 Å. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a 4-coordinate geometry to two K1+, one Cd2+, and one Ge4+ atom. In the second O2- site, O2- is bonded in a 4-coordinate geometry to two K1+, one Cd2+, and one Ge4+ atom. In the third O2- site, O2- is bonded in a 5-coordinate geometry to three K1+, one Cd2+, and one Ge4+ atom. In the fourth O2- site, O2- is bonded in a 4-coordinate geometry to two K1+, one Cd2+, and one Ge4+ atom. In the fifth O2- site, O2- is bonded in a 3-coordinate geometry to three K1+, one Cd2+, and one Ge4+ atom. In the sixth O2- site, O2- is bonded in a 4-coordinate geometry to two K1+, one Cd2+, and one Ge4+ atom. In the seventh O2- site, O2- is bonded in a 4-coordinate geometry to two K1+, one Cd2+, and one Ge4+ atom. In the eighth O2- site, O2- is bonded in a 4-coordinate geometry to two K1+, one Cd2+, and one Ge4+ atom.