F1-A2: Chemical and Phase Stabilities of Energetic Materials at High Pressures

Commonly available nonconventional energetic materials such as H2O2, ammonium nitrates (AN), and reactive materials (e.g., mixtures of metals and metal oxides), as well as conventional plastic explosives primarily made of pentaerythritol tetranitrate (PETN), cyclotrimethylene trinitramine (RDX), cyclotetramethylene-tetranitramine (HMX), and triaminotrinitrobenzene (TATB), are often subjected to materials of terrorists acts and become threats to homeland security. Thus, characterizing thermochemical properties of these materials at the blast-relevant conditions of pressure, temperature, and composition is critical for developing chemical methods to mitigate the associated threats. Our approach is to investigate phase and chemical stabilities of selected energetic materials at high pressures and different chemical environments, help characterize critical aspects of the energetic processes such as deflagration and detonation, and develop novel chemical mitigation methods that make it difficult to formulate detonable quantities of explosives. This year, our research efforts have focused on three energetic material systems of AN, TATB, and reactive metals, using diamond anvil cells, confocal micro-Raman spectroscopy, and synchrotron X-ray diffraction. Major progresses have been made: (i) to determine the phase diagram of AN, the most commonly used IED, (ii) investigate the stability of TATB, the most insensitive high explosive (HE), and (iii) Investigate the reaction pathway of reactive metals, important for thermites and nano-HE reactions. These results will lead not only to understanding of fundamental properties of these high-value energetic materials, but also to gaining insights into what causes chemical sensitivity in energetic materials and finding the conditions limiting blast or detonation of AN and energetic materials mixtures.