Materials Data on K2Na2Gd4Nb2O13 by Materials Project
K2Na2Gd4Nb2O13 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. K1+ is bonded in a 10-coordinate geometry to ten O2- atoms. There are a spread of K–O bond distances ranging from 2.81–3.30 Å. Na1+ is bonded to five O2- atoms to form distorted NaO5 trigonal bipyramids that share corners with five equivalent NbO5 trigonal bipyramids and edges with two equivalent GdO7 pentagonal bipyramids. There are a spread of Na–O bond distances ranging from 2.27–2.33 Å. There are two inequivalent Gd3+ sites. In the first Gd3+ site, Gd3+ is bonded to seven O2- atoms to form distorted GdO7 pentagonal bipyramids that share a cornercorner with one GdO7 pentagonal bipyramid, an edgeedge with one GdO7 pentagonal bipyramid, edges with two equivalent NaO5 trigonal bipyramids, and edges with two equivalent NbO5 trigonal bipyramids. There are a spread of Gd–O bond distances ranging from 2.36–2.47 Å. In the second Gd3+ site, Gd3+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Gd–O bond distances ranging from 2.34–2.57 Å. Nb5+ is bonded to five O2- atoms to form NbO5 trigonal bipyramids that share corners with five equivalent NaO5 trigonal bipyramids and edges with two equivalent GdO7 pentagonal bipyramids. There are a spread of Nb–O bond distances ranging from 1.87–2.02 Å. There are seven inequivalent O2- sites. In the first O2- site, O2- is bonded to four Gd3+ atoms to form distorted OGd4 tetrahedra that share corners with eight ONaGd2Nb tetrahedra and edges with two equivalent OGd4 tetrahedra. In the second O2- site, O2- is bonded in a 6-coordinate geometry to four equivalent K1+, one Na1+, and one Nb5+ atom. In the third O2- site, O2- is bonded to four Gd3+ atoms to form a mixture of edge and corner-sharing OGd4 tetrahedra. In the fourth O2- site, O2- is bonded in a 6-coordinate geometry to two equivalent K1+, one Na1+, two Gd3+, and one Nb5+ atom. In the fifth O2- site, O2- is bonded to one Na1+, two Gd3+, and one Nb5+ atom to form distorted corner-sharing ONaGd2Nb tetrahedra. In the sixth O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent K1+, one Na1+, two Gd3+, and one Nb5+ atom. In the seventh O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent K1+, one Na1+, two Gd3+, and one Nb5+ atom.