DOE OSTI2020
K2ScSi2O7 crystallizes in the orthorhombic Pbam space group. The structure is three-dimensional. there are four inequivalent K sites. In the first K site, K is bonded in a 3-coordinate geometry to three O atoms. There are two shorter (2.67 Å) and one longer (2.80 Å) K–O bond lengths. In the second K site, K is bonded in a 7-coordinate geometry to seven O atoms. There are a spread of K–O bond distances ranging from 2.81–3.09 Å. In the third K site, K is bonded in a 10-coordinate geometry to ten O atoms. There are a spread of K–O bond distances ranging from 2.87–3.27 Å. In the fourth K site, K is bonded in a 8-coordinate geometry to eight O atoms. There are a spread of K–O bond distances ranging from 2.81–3.07 Å. Sc is bonded to six O atoms to form ScO6 octahedra that share corners with two equivalent ScO6 octahedra and corners with four SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 15–17°. There are a spread of Sc–O bond distances ranging from 2.09–2.16 Å. There are two inequivalent Si sites. In the first Si site, Si is bonded to four O atoms to form SiO4 tetrahedra that share corners with two equivalent ScO6 octahedra and corners with two equivalent SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 0–32°. There are a spread of Si–O bond distances ranging from 1.61–1.67 Å. In the second Si site, Si is bonded to four O atoms to form SiO4 tetrahedra that share corners with two equivalent ScO6 octahedra and corners with two equivalent SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 5–35°. There are a spread of Si–O bond distances ranging from 1.61–1.68 Å. There are ten inequivalent O sites. In the first O site, O is bonded in a 2-coordinate geometry to two K, one Sc, and one Si atom. In the second O site, O is bonded in a 2-coordinate geometry to two equivalent K and two equivalent Si atoms. In the third O site, O is bonded in a distorted linear geometry to three K, one Sc, and one Si atom. In the fourth O site, O is bonded in a 2-coordinate geometry to two equivalent K and two equivalent Si atoms. In the fifth O site, O is bonded in a distorted bent 150 degrees geometry to two K and two equivalent Si atoms. In the sixth O site, O is bonded in a distorted linear geometry to two K, one Sc, and one Si atom. In the seventh O site, O is bonded in a distorted bent 150 degrees geometry to two K and two equivalent Si atoms. In the eighth O site, O is bonded in a distorted linear geometry to one K and two equivalent Sc atoms. In the ninth O site, O is bonded in a 2-coordinate geometry to two K, one Sc, and one Si atom. In the tenth O site, O is bonded in a distorted T-shaped geometry to one K and two equivalent Sc atoms.