Investigation of structural stability, electronic and mechanical properties of ternary imides Li2M(NH)2 (M = Be, Mg)

Ab initio calculations are performed to investigate the structural stability, electronic structure and mechanical properties of ternary imides Li2M(NH)(2) (M = Be, Mg) for two different crystal structures, namely alpha-orthorhombic (Iba(2)) and beta-cubic (F-43m). Among the considered structures, orthorhombic (Iba(2)) phase is found to be the most stable phase for these imides at 0K. A pressure induced structural phase transition from alpha to beta phase is observed in all the two ternary imides. The electronic structure reveals that these imides are semiconductors. The calculated elastic constants indicate that these ternary imides are mechanically stable at 0K.