DOI: 10.17188/1736839
title: Materials Data on Y7Ta3O18 by Materials Project

description: Y7Ta3O18 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. there are eight inequivalent Y3+ sites. In the first Y3+ site, Y3+ is bonded to seven O2- atoms to form distorted YO7 pentagonal bipyramids that share a cornercorner with one TaO6 octahedra, a cornercorner with one YO7 pentagonal bipyramid, a cornercorner with one TaO7 pentagonal bipyramid, an edgeedge with one TaO6 octahedra, an edgeedge with one TaO7 pentagonal bipyramid, and edges with two YO7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 50°. There are a spread of Y–O bond distances ranging from 2.21–2.54 Å. In the second Y3+ site, Y3+ is bonded in a body-centered cubic geometry to eight O2- atoms. There are a spread of Y–O bond distances ranging from 2.27–2.64 Å. In the third Y3+ site, Y3+ is bonded to seven O2- atoms to form distorted YO7 pentagonal bipyramids that share corners with two TaO6 octahedra, a cornercorner with one YO7 pentagonal bipyramid, edges with two TaO6 octahedra, and edges with three YO7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 44–47°. There are a spread of Y–O bond distances ranging from 2.21–2.47 Å. In the fourth Y3+ site, Y3+ is bonded to seven O2- atoms to form distorted YO7 pentagonal bipyramids that share corners with two TaO6 octahedra, a cornercorner with one YO7 pentagonal bipyramid, edges with two TaO6 octahedra, and edges with three YO7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 45–46°. There are a spread of Y–O bond distances ranging from 2.21–2.46 Å. In the fifth Y3+ site, Y3+ is bonded in a body-centered cubic geometry to eight O2- atoms. There are a spread of Y–O bond distances ranging from 2.31–2.62 Å. In the sixth Y3+ site, Y3+ is bonded to seven O2- atoms to form distorted YO7 pentagonal bipyramids that share a cornercorner with one TaO6 octahedra, a cornercorner with one YO7 pentagonal bipyramid, a cornercorner with one TaO7 pentagonal bipyramid, an edgeedge with one TaO6 octahedra, an edgeedge with one TaO7 pentagonal bipyramid, and edges with two YO7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 48°. There are a spread of Y–O bond distances ranging from 2.22–2.55 Å. In the seventh Y3+ site, Y3+ is bonded in a distorted body-centered cubic geometry to eight O2- atoms. There are a spread of Y–O bond distances ranging from 2.25–2.65 Å. In the eighth Y3+ site, Y3+ is bonded in a body-centered cubic geometry to eight O2- atoms. There are a spread of Y–O bond distances ranging from 2.27–2.46 Å. There are four inequivalent Ta5+ sites. In the first Ta5+ site, Ta5+ is bonded to six O2- atoms to form TaO6 octahedra that share a cornercorner with one TaO6 octahedra, a cornercorner with one TaO7 pentagonal bipyramid, corners with four YO7 pentagonal bipyramids, and edges with four YO7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 39°. There are a spread of Ta–O bond distances ranging from 1.98–2.05 Å. In the second Ta5+ site, Ta5+ is bonded to six O2- atoms to form TaO6 octahedra that share corners with two equivalent TaO6 octahedra, corners with four YO7 pentagonal bipyramids, and edges with four YO7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 39°. There are four shorter (1.99 Å) and two longer (2.02 Å) Ta–O bond lengths. In the third Ta5+ site, Ta5+ is bonded to seven O2- atoms to form distorted TaO7 pentagonal bipyramids that share a cornercorner with one TaO6 octahedra, corners with two YO7 pentagonal bipyramids, an edgeedge with one TaO7 pentagonal bipyramid, and edges with two YO7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 34°. There are a spread of Ta–O bond distances ranging from 2.00–2.18 Å. In the fourth Ta5+ site, Ta5+ is bonded in a distorted body-centered cubic geometry to eight O2- atoms. There are a spread of Ta–O bond distances ranging from 2.01–2.40 Å. There are eighteen inequivalent O2- sites. In the first O2- site, O2- is bonded to four Y3+ atoms to form a mixture of edge and corner-sharing OY4 tetrahedra. In the second O2- site, O2- is bonded in a 4-coordinate geometry to three Y3+ and one Ta5+ atom. In the third O2- site, O2- is bonded in a 4-coordinate geometry to three Y3+ and one Ta5+ atom. In the fourth O2- site, O2- is bonded in a 4-coordinate geometry to three Y3+ and one Ta5+ atom. In the fifth O2- site, O2- is bonded in a 4-coordinate geometry to three Y3+ and one Ta5+ atom. In the sixth O2- site, O2- is bonded to four Y3+ atoms to form a mixture of edge and corner-sharing OY4 tetrahedra. In the seventh O2- site, O2- is bonded to four Y3+ atoms to form a mixture of edge and corner-sharing OY4 tetrahedra. In the eighth O2- site, O2- is bonded in a 4-coordinate geometry to two Y3+ and two Ta5+ atoms. In the ninth O2- site, O2- is bonded in a 4-coordinate geometry to three Y3+ and one Ta5+ atom. In the tenth O2- site, O2- is bonded in a 4-coordinate geometry to three Y3+ and one Ta5+ atom. In the eleventh O2- site, O2- is bonded to four Y3+ atoms to form a mixture of edge and corner-sharing OY4 tetrahedra. In the twelfth O2- site, O2- is bonded in a 4-coordinate geometry to two Y3+ and two Ta5+ atoms. In the thirteenth O2- site, O2- is bonded to three Y3+ and one Ta5+ atom to form OY3Ta tetrahedra that share corners with ten OY3Ta tetrahedra and edges with three OY4 tetrahedra. In the fourteenth O2- site, O2- is bonded in a 4-coordinate geometry to two Y3+ and two Ta5+ atoms. In the fifteenth O2- site, O2- is bonded to two Y3+ and two Ta5+ atoms to form distorted OY2Ta2 tetrahedra that share corners with seven OY3Ta tetrahedra and edges with three OY4 tetrahedra. In the sixteenth O2- site, O2- is bonded to three Y3+ and one Ta5+ atom to form distorted OY3Ta tetrahedra that share corners with eight OY4 tetrahedra and edges with four OY3Ta tetrahedra. In the seventeenth O2- site, O2- is bonded to one Y3+ and three Ta5+ atoms to form a mixture of distorted edge and corner-sharing OYTa3 tetrahedra. In the eighteenth O2- site, O2- is bonded in a 4-coordinate geometry to three Y3+ and one Ta5+ atom.