摘要：We have explored the mechanical properties, electronic structures and phase transition behaviors of three designed new phases for element boron from ambient condition to high-pressure of 120 GPa including (1) a C2/c symmetric structure ( m -B16); (2) a symmetric structure ( c -B56) and (3) a Pmna symmetric structure ( o -B24). The calculation of the elastic constants and phonon dispersions shows that the phases are of mechanical and dynamic stability. The m -B16 phase is found to transform into another new phase (the o -B16 phase) when pressure exceeds 68 GPa. This might offer a new synthesis strategy for o -B16 from the metastable m -B16 at low temperature under high pressure, bypassing the thermodynamically stable γ -B28. The enthalpies of the c -B56 and o -B24 phases are observed to increase with pressure. The hardness of m -B16 and o -B16 is calculated to be about 56 GPa and 61 GPa, approaching to the highest value of 61 GPa recorded for α -Ga-B among all available Boron phases. The electronic structures and bonding characters are analyzed according to the difference charge-density and crystal orbital Hamilton population (COHP), revealing the metallic nature of the three phases.
