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All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on LaH3 by Materials Project

LaH3 is alpha bismuth trifluoride structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. La3+ is bonded to twelve H1- atoms to form a mixture of distorted edge, face, and corner-sharing LaH12 cuboctahedra. There are eight shorter (2.42 Å) and four longer (2.65 Å) La–H bond lengths. There are two inequivalent H1- sites. In the first H1- site, H1- is bonded to four equivalent La3+ atoms to form a mixture of edge and corner-sharing HLa4 tetrahedra. In the second H1- site, H1- is bonded in a square co-planar geometry to four equivalent La3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on LaH3 by Materials Project

LaH3 is alpha bismuth trifluoride structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. La3+ is bonded in a distorted body-centered cubic geometry to fourteen H1- atoms. There are eight shorter (2.41 Å) and six longer (2.79 Å) La–H bond lengths. There are two inequivalent H1- sites. In the first H1- site, H1- is bonded to six equivalent La3+ atoms to form HLa6 octahedra that share corners with six equivalent HLa6 octahedra, corners with twenty-four equivalent HLa4 tetrahedra, edges with twelve equivalent HLa6 octahedra, and faces with eight equivalent HLa4 tetrahedra. The corner-sharing octahedral tilt angles are 0°. In the second H1- site, H1- is bonded to four equivalent La3+ atoms to form HLa4 tetrahedra that share corners with twelve equivalent HLa6 octahedra, corners with sixteen equivalent HLa4 tetrahedra, edges with six equivalent HLa4 tetrahedra, and faces with four equivalent HLa6 octahedra. The corner-sharing octahedral tilt angles are 55°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on LaH3(CO2)3 by Materials Project

La(HCOO)3 crystallizes in the trigonal R3m space group. The structure is three-dimensional. La3+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of La–O bond distances ranging from 2.55–2.64 Å. C2+ is bonded in a trigonal planar geometry to one H1+ and two O2- atoms. The C–H bond length is 1.11 Å. There is one shorter (1.27 Å) and one longer (1.28 Å) C–O bond length. H1+ is bonded in a single-bond geometry to one C2+ atom. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to one La3+ and one C2+ atom. In the second O2- site, O2- is bonded in a distorted single-bond geometry to two equivalent La3+ and one C2+ atom.

36 MATERIALS SCIENCE↗
NASA NTRS1977

Studies of hydride formation and superconductivity in hydrides of alloys Th-M /M = La, Y, Ce, Zr and Bi/

In order to gain a better insight into both the unusual composition of ThH15 and its superconductivity, an experimental study was conducted to assess the influence of partial replacement of Th in Th4H15 by elements which allow for a systematic alteration of spatial and electronic effects. For this purpose, substituent elements with the same number of valence electrons (4) but of smaller size (Zr) as well as elements with a smaller number of valence electrons (3) and either larger (La) or smaller size (Y) were selected. A few data with Ce and Bi as substituent atoms are also included. The matrix alloys for hydriding were obtained by induction melting under Ar in water-cooled Cu boats. Superconducting transition temperatures are found to decrease on substitution for Th in Th4H15. Hydrides derived from LaH3 by substitution for La by Th do not become superconducting. It is suggested that superconductivity in Th4H15 is connected with a deviation from the exact stoichiometry of Th4H15. A model of unsatisfied valencies may be of more general validity in predicting superconductivity.

Oesterreicher, H.↗