Structural transition of Li3N under high pressure: A first-principles study

We theoretically study the electronic properties and pressure induced solid–solid phase transition of Li3N by first-principles calculations. The calculations indicate a pressure-induced structural phase transition above 1.5GPa from the ambient P6/MMMP6/MMM hexagonal phase (α-Li3N) to a layered hexagonal phase (β-Li3N, P63/MMC) which is accompanied by a 21.6% volume collapse. Above 38.8 GPa, β-Li3N transforms into γ-Li3N (Fm3̄m), and the recently reported new α′α′-phase (P-3M1P-3M1) is not stable under high pressure. The analysis of electronic density of states suggests that various Li3N polymorphs are insulators, and the band gap is broadened with further compression.