Quantification of Impact Sensitivity Based on Solid-State Derived Criteria

An attempt was made to develop a general description of impact sensitivity. For this purpose a set of 24 well-known, as well as recently synthesized, C-H-N-O-Cl explosives covering the wide range of impact sensitivity ( h₅₀ = 9-320 cm) was studied using first-principles calculations at different external pressures. To quantify impact sensitivity, a theoretical approach was developed based on the solid-state derived criteria, which include triggering pressure, average number of electrons per atom, crystal morphology, energy content and melting temperature. These criteria follow from the theoretical consideration of the crystal compression caused by an impact event. Apart of the compression, the influence of crystal habit shapes and energy content are also discussed. The main idea is in the electron flow probability from valence to conduction bands in a solid. To support the developed theoretical background, the corresponding numerical illustration is presented in the paper. The obtained empirical correlation exhibits a significant regression coefficient ( R² = 0.83). Furthermore, the found criteria have complementary character. When using them individually, the correlation becomes poor or even vanishes. Thus, a sensitive to impact explosive is expected to be more easily convertible to the metal upon compression, to possess a spherical crystal habit and to have a greater number of electrons per atom as well as a high energy content and a low melting temperature. Consequently, an insensitive explosive has the inverse characterization.