Materials Data on K2Na2Sm4Nb2O13 by Materials Project
K2Na2Sm4Nb2O13 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 2.83–3.30 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 SmO7 pentagonal bipyramids. There are a spread of Na–O bond distances ranging from 2.29–2.33 Å. There are two inequivalent Sm3+ sites. In the first Sm3+ site, Sm3+ is bonded to seven O2- atoms to form distorted SmO7 pentagonal bipyramids that share a cornercorner with one SmO7 pentagonal bipyramid, an edgeedge with one SmO7 pentagonal bipyramid, edges with two equivalent NaO5 trigonal bipyramids, and edges with two equivalent NbO5 trigonal bipyramids. There are a spread of Sm–O bond distances ranging from 2.37–2.47 Å. In the second Sm3+ site, Sm3+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Sm–O bond distances ranging from 2.37–2.59 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 SmO7 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 in a 4-coordinate geometry to two equivalent K1+, one Na1+, two Sm3+, and one Nb5+ atom. In the second O2- site, O2- is bonded in a 6-coordinate geometry to two equivalent K1+, one Na1+, two Sm3+, and one Nb5+ atom. In the third O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent K1+, one Na1+, two Sm3+, and one Nb5+ atom. In the fourth O2- site, O2- is bonded in a 6-coordinate geometry to four equivalent K1+, one Na1+, and one Nb5+ atom. In the fifth O2- site, O2- is bonded to four Sm3+ atoms to form distorted OSm4 tetrahedra that share corners with eight ONaSm2Nb tetrahedra and edges with two equivalent OSm4 tetrahedra. In the sixth O2- site, O2- is bonded to one Na1+, two Sm3+, and one Nb5+ atom to form distorted corner-sharing ONaSm2Nb tetrahedra. In the seventh O2- site, O2- is bonded to four Sm3+ atoms to form a mixture of edge and corner-sharing OSm4 tetrahedra.