Prediction of Stable Cu-Li Binary Intermetallics From First-Principles Calculations: Stoichiometries, Crystal Structures, and Physical Properties

Towards a resolution of the longstanding controversy regarding the existence of Cu-Li intermetallic compounds, we extensively investigate the phase stability of Cu-Li intermetallics with various possible stoichiometries at zero temperature and pressure using a global structure searching method. It is found that Cu-Li intermetallics can exist stably at atmospheric pressure, and three stable intermetallics (Fmmm Cu1Li2, Fd m Cu2Li1 and P Cu7Li1,) are identified. Electronic structure analysis reveals that although the three stable phases are metallic, covalent Cu-Cu and ionic Cu-Li bonds are found in the three structures. Moreover, the 3d states of copper atoms are mostly responsible for bond formations in the Cu-Li intermetallics. For all the predicted Cu-Li intermetallics, the effect of Cu concentration on structure, mechanical and thermodynamic properties are calculated systematically.