Lanthanum decahydride is a

polyhydride A polyhydride or superhydride is a compound that contains an abnormally large amount of hydrogen. This can be described as high hydrogen stoichiometry. Examples include iron pentahydride FeH5, LiH6, and LiH7. By contrast, the more well known lit ...

or superhydride compound of

lanthanum Lanthanum is a chemical element with the symbol La and atomic number 57. It is a soft, ductile, silvery-white metal that tarnishes slowly when exposed to air. It is the eponym of the lanthanide series, a group of 15 similar elements between lantha ...

and hydrogen (LaH₁₀) that has shown evidence of being a high-temperature superconductor. It has a superconducting transition temperature T_C ~ at a pressure of 150

gigapascal The pascal (symbol: Pa) is the unit of pressure in the International System of Units (SI), and is also used to quantify internal pressure, stress, Young's modulus, and ultimate tensile strength. The unit, named after Blaise Pascal, is defined as ...

s (GPa), and its synthesis required pressures above ~160 GPa.

Synopsis

The compound exhibits a

Meissner effect The Meissner effect (or Meissner–Ochsenfeld effect) is the expulsion of a magnetic field from a superconductor during its transition to the superconducting state when it is cooled below the critical temperature. This expulsion will repel a n ...

below the superconducting transition temperature. A cubic form can be synthesized at , and a hexagonal crystal structure can be formed at room temperature. The cubic form has each lanthanum atom surrounded by 32 hydrogen atoms, which form the vertices of an 18 faced shape called a

chamfered cube In geometry, chamfering or edge-truncation is a topological operator that modifies one polyhedron into another. It is similar to expansion, moving faces apart and outward, but also maintains the original vertices. For polyhedra, this operatio ...

. A similar compound lanthanum boron octahydride was computationally predicted to be a superconductor at 126 K with a pressure of 50 GPa.

References

{{Hydrides by group Lanthanum compounds High-temperature superconductors