Pressure-Induced Phase Transitions and Electronic Structure Evolution of BaAu.

Considering previous studies on the high-pressure phases and compressibility of Ba-Au alloys with stoichiometries AuBa, AuBa, and AuBa, the concentration of the alkaline-earth metal Ba increased, and a particle-swarm optimization algorithm was employed to conduct comprehensive structure searches for the BaAu compound at 0, 10, 20, and 50 GPa. First-principles calculations were subsequently carried out to investigate its structural evolution and electronic properties under compression. Enthalpy-difference calculations indicate that the 4 phase of BaAu transforms to the phase at approximately 0.4 GPa. As pressure increases above 5.7 GPa, the 4 structure becomes energetically more favorable than -BaAu, indicating that the phase transforms to the 4 phase at 5.7 GPa. Both phase transitions are first-order and accompanied by discernible volume collapses. Additionally, a comparative analysis of the electronic properties of BaAu was performed before and after the phase transitions. In this study, theoretical guidance is provided for the exploration of the high-pressure structural evolution of BaAu, and critical insights are offered regarding the changes that occur in its physical and chemical properties under compression.