Search for superconducting icosahedral hydrides via coordination number engineering

Superconducting hydrides provides a possible route to hunt for high-temperature superconductors. Recent high-throughput calculations suggest hydrides, which are combined by alkali or alkali-earth elements and hydrogen-and-transition-metal units, as potential candidates of superconducting hydrides under ambient pressure. Inspired by the results of high-throughput calculations. Here we propose a strategy to construct high-temperature superconductors by engineering coordination number of known hydrogen-and-transition-metal units in hydrides. Based on hydrogen-and-transition-metal unit [ReH9]2- in hydride BaReH9, we find ternary hydrides BaReH12 with different coordination number of Re from 12 to 14 as pressure increasing. Notably, a icosahedral unit [ReH12]2-, which exhibits coordination number as high as 12 in hydride BaReH12, drives superconducting critical temperature around 128 K at 100 GPa. Our results suggest that engineering coordination number of hydrogen-metal unit not only trigger the discovery of high-temperature hydride superconductors, but also attracts wide attention from high-pressure physics and coordination chemistry. The search for a room temperature superconductor is as old as the discovery of superconductors themselves and recent results for the superconducting hydrides has brough the community a step closer to this goal. Here, using a computational approach the authors investigate thermodynamically stable superconducting phases in the ternary Ba-Re-H system under high pressure, identifying several potential candidates.