Structures and properties of binary MgBi compounds under pressure

The phase diagram, crystal structures, electronic properties, bonding nature and superconductivities of binary MgBi compounds were theoretically explored under pressure. Upon compression, Mg3Bi, MgBi, MgBi2, and MgBi3 were found to be thermodynamically stable. The stable phases present metallic features as a result of notable band structures and the finite DOS at the Fermi level. The calculated ELF and Bader charge analysis indicate that there was no covalent bond with charges transferring from Mg atoms to Bi atoms. The superconducting critical temperature (Tc) value of Cmmm-MgBi is 8.19 K at 10 GPa. Further research reveals that bismuth phonon modes play a major role in the superconductivity of Cmmm-MgBi. This study provides the crystal structures and corresponding properties of magnesium-bismuth compounds, which has broad implications for further exploration on other bismuthides.