DOI: 10.17188/1704473
title: Materials Data on KNa2Tb(SiO3)8 by Materials Project

description: KNa2Tb(SiO3)8 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. K is bonded to six O atoms to form distorted KO6 octahedra that share corners with eight SiO4 tetrahedra. There are a spread of K–O bond distances ranging from 3.01–3.16 Å. There are two inequivalent Na sites. In the first Na site, Na is bonded to six O atoms to form distorted NaO6 octahedra that share corners with four SiO4 tetrahedra and edges with two TbO6 octahedra. There are a spread of Na–O bond distances ranging from 2.37–2.68 Å. In the second Na site, Na is bonded in a 8-coordinate geometry to eight O atoms. There are a spread of Na–O bond distances ranging from 2.44–2.88 Å. There are two inequivalent Tb sites. In the first Tb site, Tb is bonded to six O atoms to form TbO6 octahedra that share corners with six SiO4 tetrahedra and edges with two equivalent NaO6 octahedra. There are two shorter (2.25 Å) and four longer (2.29 Å) Tb–O bond lengths. In the second Tb site, Tb is bonded to six O atoms to form TbO6 octahedra that share corners with six SiO4 tetrahedra and edges with two equivalent NaO6 octahedra. There are four shorter (2.30 Å) and two longer (2.32 Å) Tb–O bond lengths. There are six inequivalent Si sites. In the first Si site, Si is bonded to four O atoms to form SiO4 tetrahedra that share a cornercorner with one KO6 octahedra, a cornercorner with one NaO6 octahedra, a cornercorner with one TbO6 octahedra, and corners with three SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 38–67°. There are a spread of Si–O bond distances ranging from 1.60–1.67 Å. In the second Si site, Si is bonded to four O atoms to form SiO4 tetrahedra that share a cornercorner with one TbO6 octahedra and corners with three SiO4 tetrahedra. The corner-sharing octahedral tilt angles are 29°. There is one shorter (1.61 Å) and three longer (1.64 Å) Si–O bond length. In the third Si site, Si is bonded to four O atoms to form SiO4 tetrahedra that share a cornercorner with one KO6 octahedra, a cornercorner with one NaO6 octahedra, a cornercorner with one TbO6 octahedra, and corners with three SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 41–70°. There are a spread of Si–O bond distances ranging from 1.61–1.66 Å. In the fourth Si site, Si is bonded to four O atoms to form SiO4 tetrahedra that share corners with two equivalent KO6 octahedra and corners with four SiO4 tetrahedra. The corner-sharing octahedral tilt angles are 71°. There are a spread of Si–O bond distances ranging from 1.61–1.64 Å. In the fifth Si site, Si is bonded to four O atoms to form SiO4 tetrahedra that share a cornercorner with one TbO6 octahedra and corners with three SiO4 tetrahedra. The corner-sharing octahedral tilt angles are 24°. There are a spread of Si–O bond distances ranging from 1.59–1.66 Å. In the sixth Si site, Si is bonded to four O atoms to form SiO4 tetrahedra that share corners with two equivalent KO6 octahedra and corners with four SiO4 tetrahedra. The corner-sharing octahedral tilt angles are 74°. There are a spread of Si–O bond distances ranging from 1.61–1.63 Å. There are fifteen inequivalent O sites. In the first O site, O is bonded in a bent 150 degrees geometry to two Si atoms. In the second O site, O is bonded in a distorted bent 150 degrees geometry to one K and two Si atoms. In the third O site, O is bonded in a bent 150 degrees geometry to one Tb and one Si atom. In the fourth O site, O is bonded in a linear geometry to two Si atoms. In the fifth O site, O is bonded in a 4-coordinate geometry to two Na, one Tb, and one Si atom. In the sixth O site, O is bonded in a bent 150 degrees geometry to two Si atoms. In the seventh O site, O is bonded in a bent 150 degrees geometry to two Si atoms. In the eighth O site, O is bonded in a distorted bent 150 degrees geometry to one K and two Si atoms. In the ninth O site, O is bonded in a 4-coordinate geometry to two equivalent Na, one Tb, and one Si atom. In the tenth O site, O is bonded in a bent 150 degrees geometry to two Si atoms. In the eleventh O site, O is bonded in a 3-coordinate geometry to one Na, one Tb, and one Si atom. In the twelfth O site, O is bonded in a bent 150 degrees geometry to one Na and two Si atoms. In the thirteenth O site, O is bonded in a trigonal non-coplanar geometry to two Na and one O atom. The O–O bond length is 1.31 Å. In the fourteenth O site, O is bonded in a bent 120 degrees geometry to one K and one O atom. The O–O bond length is 1.24 Å. In the fifteenth O site, O is bonded in a bent 120 degrees geometry to two equivalent O atoms.