Materials Data on La2HfO5 by Materials Project

Abstract

La2HfO5 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. there are two inequivalent La3+ sites. In the first La3+ site, La3+ is bonded to six O2- atoms to form distorted LaO6 octahedra that share corners with two equivalent LaO6 octahedra, corners with four equivalent HfO6 octahedra, and edges with six LaO6 octahedra. The corner-sharing octahedra tilt angles range from 62–65°. There are a spread of La–O bond distances ranging from 2.45–2.48 Å. In the second La3+ site, La3+ is bonded to six O2- atoms to form LaO6 octahedra that share corners with four LaO6 octahedra, corners with four equivalent HfO6 octahedra, and edges with four LaO6 octahedra. The corner-sharing octahedra tilt angles range from 52–66°. There are a spread of La–O bond distances ranging from 2.34–2.51 Å. Hf4+ is bonded to six O2- atoms to form HfO6 octahedra that share corners with two equivalent HfO6 octahedra, corners with eight LaO6 octahedra, and edges with two equivalent HfO6 octahedra. The corner-sharing octahedra tilt angles range from 34–64°. There are a spread of Hf–O bond distances ranging from 2.03–2.36 Å. There are five inequivalent O2- sites. In the first O2- site, O2- is bonded to four La3+ atoms to form OLa4 tetrahedra that share corners with ten OLa4 tetrahedra and edges with three OLa3Hf tetrahedra. In the second O2- site, O2- is bonded in a 3-coordinate geometry to three equivalent Hf4+ atoms. In the third O2- site, O2- is bonded to three La3+ and one Hf4+ atom to form a mixture of distorted edge and corner-sharing OLa3Hf tetrahedra. In the fourth O2- site, O2- is bonded to three equivalent La3+ and one Hf4+ atom to form a mixture of distorted edge and corner-sharing OLa3Hf tetrahedra. In the fifth O2- site, O2- is bonded in a 3-coordinate geometry to two equivalent La3+ and one Hf4+ atom.