Materials Data on Na2HoNb5O15 by Materials Project

Abstract

Na2HoNb5O15 crystallizes in the tetragonal P4/mbm space group. The structure is three-dimensional. Na1+ is bonded in a 6-coordinate geometry to six O2- atoms. There are two shorter (2.69 Å) and four longer (2.93 Å) Na–O bond lengths. Ho3+ is bonded to twelve O2- atoms to form HoO12 cuboctahedra that share faces with two equivalent HoO12 cuboctahedra and faces with eight equivalent NbO6 octahedra. There are four shorter (2.58 Å) and eight longer (2.66 Å) Ho–O bond lengths. There are two inequivalent Nb5+ sites. In the first Nb5+ site, Nb5+ is bonded to six O2- atoms to form corner-sharing NbO6 octahedra. The corner-sharing octahedra tilt angles range from 0–33°. There is two shorter (1.97 Å) and four longer (2.01 Å) Nb–O bond length. In the second Nb5+ site, Nb5+ is bonded to six O2- atoms to form NbO6 octahedra that share corners with six NbO6 octahedra and faces with two equivalent HoO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 13–43°. There are a spread of Nb–O bond distances ranging from 1.92–2.08 Å. There are five inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two equivalent Na1+ and two Nb5+ atoms. In the second O2- site, O2- is bonded in a 3-coordinate geometry to one Ho3+ and two equivalent Nb5+ atoms. In the third O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Na1+ and two equivalent Nb5+ atoms. In the fourth O2- site, O2- is bonded in a linear geometry to two equivalent Nb5+ atoms. In the fifth O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Ho3+ and two equivalent Nb5+ atoms.