Materials Data on KNd9(Si3O13)2 by Materials Project
KNd9(SiO4)6O2 crystallizes in the trigonal P3 space group. The structure is three-dimensional. K1+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of K–O bond distances ranging from 2.64–2.98 Å. There are five inequivalent Nd3+ sites. In the first Nd3+ site, Nd3+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Nd–O bond distances ranging from 2.29–2.72 Å. In the second Nd3+ site, Nd3+ is bonded to seven O2- atoms to form distorted NdO7 pentagonal bipyramids that share corners with two equivalent NdO7 pentagonal bipyramids, corners with four SiO4 tetrahedra, and an edgeedge with one SiO4 tetrahedra. There are a spread of Nd–O bond distances ranging from 2.31–2.59 Å. In the third Nd3+ site, Nd3+ is bonded in a 6-coordinate geometry to six O2- atoms. There are three shorter (2.44 Å) and three longer (2.47 Å) Nd–O bond lengths. In the fourth Nd3+ site, Nd3+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of Nd–O bond distances ranging from 2.44–2.79 Å. In the fifth Nd3+ site, Nd3+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of Nd–O bond distances ranging from 2.45–2.75 Å. There are two inequivalent Si4+ sites. In the first Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with two equivalent NdO7 pentagonal bipyramids. There are a spread of Si–O bond distances ranging from 1.63–1.66 Å. In the second Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with two equivalent NdO7 pentagonal bipyramids and an edgeedge with one NdO7 pentagonal bipyramid. There are a spread of Si–O bond distances ranging from 1.61–1.66 Å. There are ten inequivalent O2- sites. In the first O2- site, O2- is bonded in a 1-coordinate geometry to three Nd3+ and one Si4+ atom. In the second O2- site, O2- is bonded in a 1-coordinate geometry to one K1+, two Nd3+, and one Si4+ atom. In the third O2- site, O2- is bonded in a 1-coordinate geometry to three Nd3+ and one Si4+ atom. In the fourth O2- site, O2- is bonded in a trigonal planar geometry to three equivalent Nd3+ atoms. In the fifth O2- site, O2- is bonded in a trigonal planar geometry to three equivalent Nd3+ atoms. In the sixth O2- site, O2- is bonded in a 1-coordinate geometry to three Nd3+ and one Si4+ atom. In the seventh O2- site, O2- is bonded in a 1-coordinate geometry to one K1+, two Nd3+, and one Si4+ atom. In the eighth O2- site, O2- is bonded in a 1-coordinate geometry to two Nd3+ and one Si4+ atom. In the ninth O2- site, O2- is bonded in a 1-coordinate geometry to three Nd3+ and one Si4+ atom. In the tenth O2- site, O2- is bonded in a 1-coordinate geometry to one K1+, two Nd3+, and one Si4+ atom.