Phase transition induced by an external electric field as a buffer to facilitate the initial decomposition of a series of catenated nitrogen energetic systems: a first-principles study

The effect of an external electric field on the crystal and electronic structures, Hirshfeld surfaces, hydrogen-bonding network, mechanical properties, vibrational properties and initial decomposition mechanisms of a series of chain-catenated N_x (x = 4, 8, 10) energetic crystals was investigated via a first-principles study. The results indicate that the response behaviors to the external electric field show a great dependence on the nitrogen chain length and the intensity of the external electric field. The critical points of the phase transition were found and are embodied in various properties of all the compounds. Analysis of the electronic structures shows the increasing ability of the electron transition, thereby leading to possible subsequent decomposition reactions. The studies on Hirshfeld surfaces and the hydrogen-bonding network suggest that the external electric field can modify and tune the spatial distribution of the hydrogen-bonding network, thereby affecting the physicochemical properties. Our comprehensive analysis based on the mechanical properties, vibrational features and initial decomposition mechanism reveals that the external electric field can weaken the trigger bonds, reduce the thermal stability, and initiate decomposition. Our findings provide insights into the comprehensive understanding of the effects of an external electric field on energetic materials, especially for polynitrogen chain-catenated and even all-nitrogen compounds.