Materials Data on KTaSi2O7 by Materials Project
KTaSi2O7 crystallizes in the tetragonal P4/mbm space group. The structure is three-dimensional. K1+ is bonded in a 12-coordinate geometry to twelve O2- atoms. There are a spread of K–O bond distances ranging from 2.88–3.27 Å. Ta5+ is bonded to six O2- atoms to form TaO6 octahedra that share corners with two equivalent TaO6 octahedra and corners with four equivalent SiO4 tetrahedra. The corner-sharing octahedral tilt angles are 0°. There are a spread of Ta–O bond distances ranging from 1.99–2.01 Å. Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with two equivalent TaO6 octahedra and corners with two equivalent SiO4 tetrahedra. The corner-sharing octahedral tilt angles are 23°. There are a spread of Si–O bond distances ranging from 1.60–1.66 Å. There are five inequivalent O2- sites. In the first O2- site, O2- is bonded in a linear geometry to two equivalent Si4+ atoms. In the second O2- site, O2- is bonded in a linear geometry to four equivalent K1+ and two equivalent Ta5+ atoms. In the third O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent K1+ and two equivalent Si4+ atoms. In the fourth O2- site, O2- is bonded in a linear geometry to two equivalent Ta5+ atoms. In the fifth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two equivalent K1+, one Ta5+, and one Si4+ atom.