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All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on La2HfO5 by Materials Project

La2HfO5 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are four inequivalent La3+ sites. In the first La3+ site, La3+ is bonded in a 4-coordinate geometry to four O2- atoms. There are a spread of La–O bond distances ranging from 1.75–2.51 Å. In the second La3+ site, La3+ is bonded in a 1-coordinate geometry to four O2- atoms. There are a spread of La–O bond distances ranging from 1.95–2.54 Å. In the third La3+ site, La3+ is bonded in a 1-coordinate geometry to four O2- atoms. There are a spread of La–O bond distances ranging from 1.96–2.53 Å. In the fourth La3+ site, La3+ is bonded in a 2-coordinate geometry to four O2- atoms. There are a spread of La–O bond distances ranging from 1.76–2.53 Å. There are two inequivalent Hf4+ sites. In the first Hf4+ site, Hf4+ is bonded in a distorted square co-planar geometry to four O2- atoms. There are a spread of Hf–O bond distances ranging from 1.36–2.12 Å. In the second Hf4+ site, Hf4+ is bonded in a 2-coordinate geometry to four O2- atoms. There are two shorter (1.79 Å) and two longer (2.27 Å) Hf–O bond lengths. There are ten inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one La3+ and one Hf4+ atom. In the second O2- site, O2- is bonded in a 3-coordinate geometry to two La3+ and one Hf4+ atom. In the third O2- site, O2- is bonded in a 2-coordinate geometry to two La3+ and one Hf4+ atom. In the fourth O2- site, O2- is bonded in a water-like geometry to one La3+ and one Hf4+ atom. In the fifth O2- site, O2- is bonded in a water-like geometry to one La3+ and one Hf4+ atom. In the sixth O2- site, O2- is bonded in a 2-coordinate geometry to two La3+ and one Hf4+ atom. In the seventh O2- site, O2- is bonded in a 1-coordinate geometry to two La3+ and one Hf4+ atom. In the eighth O2- site, O2- is bonded in an L-shaped geometry to two La3+ atoms. In the ninth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one La3+ and one Hf4+ atom. In the tenth O2- site, O2- is bonded in a distorted L-shaped geometry to two La3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on La2HfO5 by Materials Project

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 seven O2- atoms to form distorted LaO7 hexagonal pyramids that share corners with three equivalent HfO5 trigonal bipyramids, edges with two equivalent LaO7 hexagonal pyramids, and edges with two equivalent HfO5 trigonal bipyramids. There are a spread of La–O bond distances ranging from 2.42–2.59 Å. In the second La3+ site, La3+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of La–O bond distances ranging from 2.48–2.58 Å. Hf4+ is bonded to five O2- atoms to form distorted HfO5 trigonal bipyramids that share corners with three equivalent LaO7 hexagonal pyramids, corners with two equivalent HfO5 trigonal bipyramids, and edges with two equivalent LaO7 hexagonal pyramids. There are a spread of Hf–O bond distances ranging from 1.94–2.08 Å. There are five inequivalent O2- sites. In the first O2- site, O2- is bonded to four La3+ atoms to form a mixture of edge and corner-sharing OLa4 tetrahedra. In the second O2- site, O2- is bonded in a distorted trigonal planar geometry to two equivalent La3+ and one Hf4+ atom. In the third O2- site, O2- is bonded to three La3+ and one Hf4+ atom to form OLa3Hf tetrahedra that share corners with eight OLa4 tetrahedra and edges with two equivalent OLa3Hf tetrahedra. In the fourth 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 fifth O2- site, O2- is bonded in a 4-coordinate geometry to two La3+ and two equivalent Hf4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on La2HfO5 by Materials Project

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.

36 MATERIALS SCIENCE↗