Eur. Phys. J. B 61, 397-403 (2008)
https://doi.org/10.1140/epjb/e2008-00107-0

First-principles study of high pressure phase transformations in Li₃N

¹ National Lab of Superhard Materials, Jilin University, Changchun, 130012, P.R. China
² Applied Physics Institute, Changchun University, Changchun, 130022, P.R. China

Corresponding author: ^a mym@jlu.edu.cn

Received: 26 September 2007
Revised: 27 January 2008
Published online: 13 March 2008

Abstract

The lattice dynamics of lithium nitride (Li₃N) under high pressure are extensively investigated to probe its phase transformations by using the pseudopotential plane-wave method within the density functional theory. A new second order α↦α^′-Li₃N phase transition is identified for the first time. The newly proposed α^′-phase possesses a hexagonal symmetry with four ions in the unit cell having a space group of P-3m1. Further enthalpy and phonon calculations support the existence of this phase, which stabilizes in a narrow pressure range of 2.8 – 3.6 GPa at zero temperature. Upon further compression, transitions to denser packed phases of β-and γ-Li₃N are typical first order. The analysis of the electronic densities of states suggests that all the high pressure modifications of Li₃N are insulators and, interestingly, the typical behavior of compression is to broaden the band gap.