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All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on KNaEuNbO5 by Materials Project

KNaEuNbO5 crystallizes in the tetragonal P4/nmm space group. The structure is three-dimensional. K1+ is bonded in a distorted square co-planar geometry to four equivalent O2- atoms. All K–O bond lengths are 2.90 Å. Na1+ is bonded to five O2- atoms to form distorted NaO5 trigonal bipyramids that share corners with five equivalent NbO5 trigonal bipyramids. There are four shorter (2.31 Å) and one longer (2.34 Å) Na–O bond lengths. Eu3+ is bonded in a body-centered cubic geometry to eight equivalent O2- atoms. All Eu–O bond lengths are 2.49 Å. Nb5+ is bonded to five O2- atoms to form distorted NbO5 trigonal bipyramids that share corners with five equivalent NaO5 trigonal bipyramids. There is one shorter (1.87 Å) and four longer (1.98 Å) Nb–O bond length. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded to four equivalent K1+, one Na1+, and one Nb5+ atom to form a mixture of distorted corner and edge-sharing OK4NaNb octahedra. The corner-sharing octahedral tilt angles are 12°. In the second O2- site, O2- is bonded in a 4-coordinate geometry to one Na1+, two equivalent Eu3+, and one Nb5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K2Na2Eu4Nb2O13 by Materials Project

K2Na2Eu4Nb2O13 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 2.84–3.31 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 EuO7 pentagonal bipyramids. There are a spread of Na–O bond distances ranging from 2.30–2.35 Å. There are two inequivalent Eu3+ sites. In the first Eu3+ site, Eu3+ is bonded to seven O2- atoms to form distorted EuO7 pentagonal bipyramids that share a cornercorner with one EuO7 pentagonal bipyramid, an edgeedge with one EuO7 pentagonal bipyramid, edges with two equivalent NaO5 trigonal bipyramids, and edges with two equivalent NbO5 trigonal bipyramids. There are a spread of Eu–O bond distances ranging from 2.40–2.49 Å. In the second Eu3+ site, Eu3+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Eu–O bond distances ranging from 2.38–2.58 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 EuO7 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 Eu3+, and one Nb5+ atom. In the second O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent K1+, one Na1+, two Eu3+, and one Nb5+ atom. In the third O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent K1+, one Na1+, two Eu3+, 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 Eu3+ atoms to form OEu4 tetrahedra that share corners with eight ONaEu2Nb tetrahedra and edges with two equivalent OEu4 tetrahedra. In the sixth O2- site, O2- is bonded to one Na1+, two Eu3+, and one Nb5+ atom to form distorted corner-sharing ONaEu2Nb tetrahedra. In the seventh O2- site, O2- is bonded to four Eu3+ atoms to form a mixture of edge and corner-sharing OEu4 tetrahedra.

36 MATERIALS SCIENCE↗