Synthesis of molecular metallic barium superhydride: pseudocubic BaH<sub>12</sub>.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 33431840.
- Also identified by DOI 10.1038/s41467-020-20103-5 and PMC identifier 7801595.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Following the discovery of high-temperature superconductivity in the La-H system, we studied the formation of new chemical compounds in the barium-hydrogen system at pressures from 75 to 173 GPa. Using in situ generation of hydrogen from NH<sub>3</sub>BH<sub>3</sub>, we synthesized previously unknown superhydride BaH<sub>12</sub> with a pseudocubic (fcc) Ba sublattice in four independent experiments. Density functional theory calculations indicate close agreement between the theoretical and experimental equations of state. In addition, we identified previously known P6/mmm-BaH<sub>2</sub> and possibly BaH<sub>10</sub> and BaH<sub>6</sub> as impurities in the samples. Ab initio calculations show that newly discovered semimetallic BaH<sub>12</sub> contains H<sub>2</sub> and H<sub>3</sub><sup>-</sup> molecular units and detached H<sub>12</sub> chains which are formed as a result of a Peierls-type distortion of the cubic cage structure. Barium dodecahydride is a unique molecular hydride with metallic conductivity that demonstrates the superconducting transition around 20 K at 140 GPa.