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All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on LaFe5H2 by Materials Project

LaFe5H2 crystallizes in the orthorhombic Cmmm space group. The structure is three-dimensional. La is bonded in a 4-coordinate geometry to ten Fe and four equivalent H atoms. There are a spread of La–Fe bond distances ranging from 2.97–3.31 Å. All La–H bond lengths are 2.40 Å. There are three inequivalent Fe sites. In the first Fe site, Fe is bonded in a linear geometry to six Fe and two equivalent H atoms. There are four shorter (2.57 Å) and two longer (2.60 Å) Fe–Fe bond lengths. Both Fe–H bond lengths are 1.66 Å. In the second Fe site, Fe is bonded in a 12-coordinate geometry to three equivalent La and nine Fe atoms. There are a spread of Fe–Fe bond distances ranging from 2.54–3.02 Å. In the third Fe site, Fe is bonded to four equivalent La and eight Fe atoms to form distorted FeLa4Fe8 cuboctahedra that share corners with eight equivalent FeLa4Fe8 cuboctahedra, corners with eight equivalent HLa2Fe2 tetrahedra, edges with two equivalent FeLa4Fe8 cuboctahedra, edges with two equivalent HLa2Fe2 tetrahedra, faces with two equivalent FeLa4Fe8 cuboctahedra, and faces with four equivalent HLa2Fe2 tetrahedra. H is bonded to two equivalent La and two equivalent Fe atoms to form HLa2Fe2 tetrahedra that share corners with four equivalent FeLa4Fe8 cuboctahedra, corners with six equivalent HLa2Fe2 tetrahedra, an edgeedge with one FeLa4Fe8 cuboctahedra, an edgeedge with one HLa2Fe2 tetrahedra, and faces with two equivalent FeLa4Fe8 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on LaFe5H7 by Materials Project

LaFe5H7 crystallizes in the hexagonal P6_3mc space group. The structure is three-dimensional. La is bonded to twelve H atoms to form LaH12 cuboctahedra that share corners with six equivalent LaH12 cuboctahedra, corners with six equivalent FeH4 trigonal pyramids, edges with three equivalent FeH4 tetrahedra, edges with six equivalent FeH4 trigonal pyramids, and faces with two equivalent LaH12 cuboctahedra. There are a spread of La–H bond distances ranging from 2.48–2.84 Å. There are three inequivalent Fe sites. In the first Fe site, Fe is bonded to four H atoms to form FeH4 trigonal pyramids that share corners with two equivalent LaH12 cuboctahedra, corners with two equivalent FeH4 tetrahedra, corners with four equivalent FeH4 trigonal pyramids, and edges with two equivalent LaH12 cuboctahedra. There is two shorter (1.73 Å) and two longer (1.74 Å) Fe–H bond length. In the second Fe site, Fe is bonded in a 3-coordinate geometry to four H atoms. There is three shorter (1.71 Å) and one longer (2.12 Å) Fe–H bond length. In the third Fe site, Fe is bonded to four H atoms to form FeH4 tetrahedra that share corners with six equivalent FeH4 trigonal pyramids and edges with three equivalent LaH12 cuboctahedra. There is three shorter (1.71 Å) and one longer (1.83 Å) Fe–H bond length. There are three inequivalent H sites. In the first H site, H is bonded to two equivalent La and two equivalent Fe atoms to form distorted HLa2Fe2 tetrahedra that share corners with eight equivalent HLa2Fe2 tetrahedra, corners with two equivalent HFe5 trigonal bipyramids, and edges with two equivalent HLa2Fe2 tetrahedra. In the second H site, H is bonded to five Fe atoms to form corner-sharing HFe5 trigonal bipyramids. In the third H site, H is bonded in a 3-coordinate geometry to two equivalent La and three Fe atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on LaFe5H12 by Materials Project

LaFe5H12 crystallizes in the hexagonal P6/mmm space group. The structure is three-dimensional. La2+ is bonded to twelve equivalent H1- atoms to form LaH12 cuboctahedra that share edges with six equivalent FeH6 pentagonal pyramids. All La–H bond lengths are 2.40 Å. There are two inequivalent Fe2+ sites. In the first Fe2+ site, Fe2+ is bonded in a body-centered cubic geometry to eight equivalent H1- atoms. All Fe–H bond lengths are 1.80 Å. In the second Fe2+ site, Fe2+ is bonded to six equivalent H1- atoms to form distorted FeH6 pentagonal pyramids that share edges with three equivalent LaH12 cuboctahedra. All Fe–H bond lengths are 1.64 Å. H1- is bonded to one La2+ and three Fe2+ atoms to form a mixture of distorted edge and corner-sharing HLaFe3 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on LaFe5H7 by Materials Project

LaFe5H7 crystallizes in the orthorhombic Cccm space group. The structure is three-dimensional. La is bonded in a 10-coordinate geometry to ten H atoms. There are a spread of La–H bond distances ranging from 2.38–2.77 Å. There are three inequivalent Fe sites. In the first Fe site, Fe is bonded to four equivalent H atoms to form distorted corner-sharing FeH4 tetrahedra. All Fe–H bond lengths are 1.71 Å. In the second Fe site, Fe is bonded to five H atoms to form distorted FeH5 trigonal bipyramids that share corners with two equivalent FeH4 tetrahedra and corners with three equivalent FeH5 trigonal bipyramids. There are a spread of Fe–H bond distances ranging from 1.70–1.92 Å. In the third Fe site, Fe is bonded in a distorted T-shaped geometry to three H atoms. There is two shorter (1.73 Å) and one longer (1.76 Å) Fe–H bond length. There are three inequivalent H sites. In the first H site, H is bonded to two equivalent La and four Fe atoms to form distorted HLa2Fe4 octahedra that share corners with two equivalent HLa2Fe4 octahedra, corners with twenty HLa2Fe2 tetrahedra, and edges with four equivalent HLa2Fe2 tetrahedra. The corner-sharing octahedral tilt angles are 0°. In the second H site, H is bonded to two equivalent La and two equivalent Fe atoms to form distorted HLa2Fe2 tetrahedra that share corners with two equivalent HLa2Fe4 octahedra, corners with fourteen HLa2Fe2 tetrahedra, edges with two equivalent HLa2Fe4 octahedra, and edges with three HLa2Fe2 tetrahedra. The corner-sharing octahedral tilt angles are 60°. In the third H site, H is bonded to one La and three Fe atoms to form distorted HLaFe3 tetrahedra that share corners with four equivalent HLa2Fe4 octahedra, corners with ten HLa2Fe2 tetrahedra, and edges with two HLa2Fe2 tetrahedra. The corner-sharing octahedra tilt angles range from 47–92°.

36 MATERIALS SCIENCE↗