Prediction of high-Tc superconductivity under submegabar pressure in ternary actinium borohydrides

TL;DR

This study predicts high-temperature superconductivity in ternary actinium borohydrides at submegabar pressures using first-principles calculations, identifying stable compounds with potential Tc up to 122 K, guiding future experimental synthesis.

Contribution

It introduces a comprehensive computational analysis of Ac-B-H compounds, revealing stable structures and high Tc superconductivity at moderate pressures, which is novel in this material system.

Findings

Nine stable Ac-B-H compounds identified.

AcBH7 estimated to have Tc of 122 K at 70 GPa.

B-H interactions in BH6 units are crucial for high Tc.

Abstract

Ternary hydrides are considered as the ideal candidates with high critical temperature (Tc) stabilized at submegabar pressure, evidenced by the recent discoveries in LaBeH8 (110 K at 80 GPa) and LaB2H8 (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 BHx motifs, e.g., methanelike (BH4), polythenelike, (BH2)n,andBH6 octahedron. Among them, seven Ac-B-H compounds were found to become superconductive. In particular, AcBH7 was estimated to have a Tc of 122 K at 70 GPa. Our in-depth analysis reveals that the B-H interactions in the BH6 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-Tc at moderate pressure.