Materials Data on KNaCu(Si2O5)2 by Materials Project
KNaCu(Si2O5)2 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. K1+ is bonded in a 4-coordinate geometry to ten O2- atoms. There are a spread of K–O bond distances ranging from 2.71–3.42 Å. Na1+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Na–O bond distances ranging from 2.41–2.96 Å. Cu2+ is bonded to five O2- atoms to form distorted CuO5 square pyramids that share corners with five SiO4 tetrahedra and an edgeedge with one CuO5 square pyramid. There are a spread of Cu–O bond distances ranging from 1.98–2.73 Å. There are four inequivalent Si4+ sites. In the first Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share a cornercorner with one CuO5 square pyramid and corners with three SiO4 tetrahedra. There are a spread of Si–O bond distances ranging from 1.60–1.65 Å. In the second Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with two equivalent CuO5 square pyramids and corners with three SiO4 tetrahedra. There are a spread of Si–O bond distances ranging from 1.60–1.66 Å. In the third Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share a cornercorner with one CuO5 square pyramid and corners with three SiO4 tetrahedra. There are a spread of Si–O bond distances ranging from 1.60–1.65 Å. In the fourth Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share a cornercorner with one CuO5 square pyramid and corners with three SiO4 tetrahedra. There are a spread of Si–O bond distances ranging from 1.60–1.66 Å. There are ten inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to one K1+, one Na1+, and two Si4+ atoms. In the second O2- site, O2- is bonded in a 1-coordinate geometry to one Na1+, two equivalent Cu2+, and one Si4+ atom. In the third O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two equivalent K1+ and two Si4+ atoms. In the fourth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one K1+ and two Si4+ atoms. In the fifth O2- site, O2- is bonded to two equivalent Na1+, one Cu2+, and one Si4+ atom to form distorted edge-sharing ONa2CuSi trigonal pyramids. In the sixth O2- site, O2- is bonded in a 2-coordinate geometry to one K1+, one Na1+, one Cu2+, and one Si4+ atom. In the seventh O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent K1+ and two Si4+ atoms. In the eighth O2- site, O2- is bonded in a 4-coordinate geometry to one K1+, one Na1+, one Cu2+, and one Si4+ atom. In the ninth O2- site, O2- is bonded in a 2-coordinate geometry to one K1+, one Na1+, and two Si4+ atoms. In the tenth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one K1+ and two Si4+ atoms.