Synthesis and Stability of Lanthanum Superhydrides.

Title Synthesis and Stability of Lanthanum Superhydrides.
Authors Z.M. Geballe; H. Liu; A.K. Mishra; M. Ahart; M. Somayazulu; Y. Meng; M. Baldini; R.J. Hemley
Journal Angew Chem Int Ed Engl
DOI 10.1002/anie.201709970

Recent theoretical calculations predict that megabar pressure stabilizes very hydrogen-rich simple compounds having new clathrate-like structures and remarkable electronic properties including room-temperature superconductivity. X-ray diffraction and optical studies demonstrate that superhydrides of lanthanum can be synthesized with La atoms in an fcc lattice at 170?GPa upon heating to about 1000?K. The results match the predicted cubic metallic phase of LaH10 having cages of thirty-two hydrogen atoms surrounding each La atom. Upon decompression, the fcc-based structure undergoes a rhombohedral distortion of the La sublattice. The superhydride phases consist of an atomic hydrogen sublattice with H-H distances of about 1.1?Å, which are close to predictions for solid atomic metallic hydrogen at these pressures. With stability below 200?GPa, the superhydride is thus the closest analogue to solid atomic metallic hydrogen yet to be synthesized and characterized.

Citation Z.M. Geballe; H. Liu; A.K. Mishra; M. Ahart; M. Somayazulu; Y. Meng; M. Baldini; R.J. Hemley.Synthesis and Stability of Lanthanum Superhydrides.. Angew Chem Int Ed Engl. 2018;57(3):688692. doi:10.1002/anie.201709970

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See more Lanthanum products. Lanthanum (atomic symbol: La, atomic number: 57) is a Block F, Group 3, Period 6 element with an atomic weight of 138.90547. Lanthanum Bohr ModelThe number of electrons in each of lanthanum's shells is [2, 8, 18, 18, 9, 2] and its electron configuration is [Xe] 5d1 6s2. The lanthanum atom has a radius of 187 pm and a Van der Waals radius of 240 pm. Lanthanum was first discovered by Carl Mosander in 1838. In its elemental form, lanthanum has a silvery white appearance.Elemental Lanthanum It is a soft, malleable, and ductile metal that oxidizes easily in air. Lanthanum is the first element in the rare earth or lanthanide series. It is the model for all the other trivalent rare earths and it is the second most abundant of the rare earths after cerium. Lanthanum is found in minerals such as monazite and bastnasite. The name lanthanum originates from the Greek word Lanthaneia, which means 'to lie hidden'.

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