A study of the reactivity of silver azide based on calculations of the band properties within the framework of density functional theory

Density functional theory methods in the basis of localized orbitals are used to study structural, electronic, vibrational, and thermodynamic properties, as well as the reactivity of the orthorhombic, tetragonal, and monoclinic phases of silver azide. The effects of pressure and temperature are described using the Debye quasi-harmonic model. The reactivity of silver azide is analyzed in terms of the enthalpy and entropy factors and equilibrium constants. It is shown that, for the solid-phase decomposition, a decrease in the volume (increase in pressure) leads to a decrease in the enthalpy, whereas the entropy factor remains virtually unchanged. As a result, at a pressure of 11.6 GPa, the reaction of direct generation of holes becomes feasible and then, above 14.8 GPa, exothermic. The formation of small nuclei of silver dinitride-nitride AgNN₂ metastable phase is considered as a possible mechanism of generation of reaction kernels.