Materials Data on La3Mg2NbO9 by Materials Project

Abstract

Mg2La3NbO9 crystallizes in the orthorhombic Immm space group. The structure is three-dimensional. there are three inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with two equivalent MgO6 octahedra, corners with four equivalent NbO6 octahedra, and faces with four equivalent LaO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 0–5°. There are two shorter (2.00 Å) and four longer (2.03 Å) Mg–O bond lengths. In the second Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with two equivalent MgO6 octahedra, corners with four equivalent NbO6 octahedra, and faces with two equivalent LaO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 1–12°. There are two shorter (2.00 Å) and four longer (2.03 Å) Mg–O bond lengths. In the third Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with six MgO6 octahedra and faces with four equivalent LaO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 0–1°. There are four shorter (1.99 Å) and two longer (2.01 Å) Mg–O bond lengths. There are two inequivalent La3+ sites. In the first La3+ site, La3+ is bonded to twelve O2- atoms to form distorted LaO12 cuboctahedra that share corners with two equivalent LaO12 cuboctahedra, faces with two equivalent LaO12 cuboctahedra, faces with two equivalent NbO6 octahedra, and faces with six MgO6 octahedra. There are a spread of La–O bond distances ranging from 2.67–3.08 Å. In the second La3+ site, La3+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of La–O bond distances ranging from 2.52–2.85 Å. Nb5+ is bonded to six O2- atoms to form NbO6 octahedra that share corners with six MgO6 octahedra and faces with two equivalent LaO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 5–12°. There are a spread of Nb–O bond distances ranging from 1.98–2.01 Å. There are five inequivalent O2- sites. In the first O2- site, O2- is bonded in a 6-coordinate geometry to two Mg2+ and four La3+ atoms. In the second O2- site, O2- is bonded in a 2-coordinate geometry to one Mg2+, three La3+, and one Nb5+ atom. In the third O2- site, O2- is bonded to two Mg2+ and four La3+ atoms to form a mixture of distorted corner, edge, and face-sharing OLa4Mg2 octahedra. The corner-sharing octahedral tilt angles are 0°. In the fourth O2- site, O2- is bonded in a distorted linear geometry to one Mg2+, two equivalent La3+, and one Nb5+ atom. In the fifth O2- site, O2- is bonded in a distorted linear geometry to one Mg2+, four La3+, and one Nb5+ atom.