Publication Date:
2018-10-13
Description:
Hydrogen-rich hydrides attract great attention due to recent theoretical ( 1 ) and then experimental discovery of record high-temperature superconductivity in H 3 S [ T c = 203 K at 155 GPa ( 2 )]. Here we search for stable uranium hydrides at pressures up to 500 GPa using ab initio evolutionary crystal structure prediction. Chemistry of the U-H system turned out to be extremely rich, with 14 new compounds, including hydrogen-rich UH 5 , UH 6 , U 2 H 13 , UH 7 , UH 8 , U 2 H 17 , and UH 9 . Their crystal structures are based on either common face-centered cubic or hexagonal close-packed uranium sublattice and unusual H 8 cubic clusters. Our high-pressure experiments at 1 to 103 GPa confirm the predicted UH 7 , UH 8 , and three different phases of UH 5 , raising confidence about predictions of the other phases. Many of the newly predicted phases are expected to be high-temperature superconductors. The highest- T c superconductor is UH 7 , predicted to be thermodynamically stable at pressures above 22 GPa (with T c = 44 to 54 K), and this phase remains dynamically stable upon decompression to zero pressure (where it has T c = 57 to 66 K).
Electronic ISSN:
2375-2548
Topics:
Natural Sciences in General
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