Compressed hydrides of the heavy group-15 elements Bi and Sb are investigated using ab initio methods. While the hydrides of Bi and Sb are known to be quite unstable at one atmosphere, our calculations predict that they can be stabilized at high pressures. Thus, at the composition of ${X\mathrm{H}}_3$ ($X=\text{Bi}$ or Sb), possible Bi hydrides are ${\mathrm{BiH}}_2\left(Pnma\right)$ + H beyond 105 GPa and ${\mathrm{BiH}}_3\left(I{4}_1/amd\right)$ beyond 250 GPa; for Sb hydrides, ${\mathrm{SbH}}_2$ + H hardly appears, and ${\mathrm{SbH}}_3\left(Pnma\right)$ is stabilized beyond 150 GPa. All of these hydrides are metallic with very dispersive electronic structures, this being in accordance with the predictions of the Goldhammer-Herzfeld criterion. Superconducting transition temperatures have also been estimated from the extended McMillan equation, and they turn out to be 39 K for ${\mathrm{BiH}}_2$ at 125 GPa, 65 K for ${\mathrm{BiH}}_3$ at 270 GPa, and 68 K for ${\mathrm{SbH}}_3$ at 170 GPa.

• Received 14 September 2015

DOI:https://doi.org/10.1103/PhysRevB.92.224109