Materials Data on KNaGdNbO5 by Materials Project

Abstract

KNaGdNbO5 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 2.88 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 (2.30 Å) and one longer (2.34 Å) Na–O bond lengths. Gd3+ is bonded in a body-centered cubic geometry to eight equivalent O2- atoms. All Gd–O bond lengths are 2.45 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 (1.88 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 distorted OK4NaNb octahedra that share corners with four equivalent OK4NaNb octahedra, corners with eight equivalent ONaGd2Nb tetrahedra, and edges with four equivalent OK4NaNb octahedra. The corner-sharing octahedral tilt angles are 12°. In the second O2- site, O2- is bonded to one Na1+, two equivalent Gd3+, and one Nb5+ atom to form distorted ONaGd2Nb tetrahedra that share corners with two equivalent OK4NaNb octahedra, corners with ten equivalent ONaGd2Nb tetrahedra, and edges with five equivalent ONaGd2Nb tetrahedra. The corner-sharing octahedra tilt angles range from 70–72°.