Negative linear compressibility and structural phase transition in energetic silver azide under pressure: A first principles study

Abstract

In this work, we have investigated high pressure behavior of silver azide within the framework of dispersion corrected density functional theory. We have predicted a pressure induced first order structural phase transition from orthorhombic (Ibam) → tetragonal (I4∕mcm) phase at 3.1 GPa. Ambient phase exhibits negative linear compressibility along a-axis in agreement with the experiments. Calculated phonon dispersion relations confirm the dynamical stability of ambient and high pressure phases. We have also analyzed bonding nature of alkali and transition metal azides, this provides an insight on possible correlation between structure-bonding-stability. The bonding nature between metal and terminal nitrogen of azide plays a predominant role in determining the order of stability in inorganic metal azides.