Prediction of high- <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>T</mml:mi> <mml:mi>c</mml:mi> </mml:msub> </mml:math> superconductivity under submegabar pressure in ternary actinium borohydrides
Tingting Gu, Wenwen Cui, Jian Hao, Jingming Shi, Artur P. Durajski, Hanyu Liu, Yinwei Li
Abstract
Ternary hydrides are considered as the ideal candidates with high critical temperature $({T}_{c})$ stabilized at submegabar pressure, evidenced by the recent discoveries in ${\mathrm{LaBeH}}_{8}$ (110 K at 80 GPa) and ${\mathrm{LaB}}_{2}{\mathrm{H}}_{8}$ (106 K at 90 GPa). Here, we investigate the crystal structures and superconductivity of an Ac-B-H system under pressures of 100 and 200 GPa by using an advanced structure method combined with first-principles calculations. As a result, nine stable compounds were identified, where B atoms are bonded with H atoms in the formation with diverse ${\mathrm{BH}}_{x}$ motifs, e.g., methanelike $({\mathrm{BH}}_{4})$, polythenelike, ${({\mathrm{BH}}_{2})}_{n}$, and ${\mathrm{BH}}_{6}$ octahedron. Among them, seven Ac-B-H compounds were found to become superconductive. In particular, ${\mathrm{AcBH}}_{7}$ was estimated to have a ${T}_{c}$ of 122 K at 70 GPa. Our in-depth analysis reveals that the B-H interactions in the ${\mathrm{BH}}_{6}$ units play a key role in its high superconductivity and stability at submegabar pressure. Our current results provide a guidance for future experiments to synthesize ternary hydride superconductors with high-${T}_{c}$ at moderate pressure.