Phase stability, mechanical property, and electronic structure of Mg–Li system

First principle calculation reveals that the HCP, BCC, and FCC Mg100−xLix phases are energetically favorable with negative heats of formation, and are predicted to be the most stable structures at 0 K when 0 ≤ x < 18, 18 ≤ x < 73, and 73 ≤ x ≤ 100, respectively. Calculation also shows that for Mg–Li phases there is an almost linear variation of bulk moduli with composition, and crystal structure has only a little effect on bulk moduli. In addition, it is found that Mg3Li and MgLi have phase sequences of BCC → HCP → FCC and BCC → FCC under high pressure, respectively, and that the anomalous mechanical instability of the HCP MgLi phase would be attributed to its weak bonding and step-like electronic structure of valence bands.