Materials Data on KNaLaTaO5 by Materials Project

Abstract

LaKNaTaO5 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 2.94 Å. Na1+ is bonded to five O2- atoms to form distorted NaO5 trigonal bipyramids that share corners with five equivalent TaO5 trigonal bipyramids. There are one shorter (2.28 Å) and four longer (2.35 Å) Na–O bond lengths. La3+ is bonded in a body-centered cubic geometry to eight equivalent O2- atoms. All La–O bond lengths are 2.54 Å. Ta5+ is bonded to five O2- atoms to form distorted TaO5 trigonal bipyramids that share corners with five equivalent NaO5 trigonal bipyramids. There is one shorter (1.86 Å) and four longer (1.98 Å) Ta–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 Ta5+ atom to form a mixture of distorted edge and corner-sharing OK4NaTa octahedra. The corner-sharing octahedral tilt angles are 10°. In the second O2- site, O2- is bonded in a 4-coordinate geometry to one Na1+, two equivalent La3+, and one Ta5+ atom.