Experimental and theoretical investigation into the high pressure deflagration products of 2,6-diamino-3,5-dinitropyrazine-1-oxide (LLM-105)

Diamond anvil cell (DAC) laser ignition experiments and reactive ab initio molecular dynamics (AIMD) simulations were performed on the high explosive (HE) LLM-105 to investigate its high pressure (HP) deflagration chemistry. Raman and optical spectroscopy measurements reveal LLM-105 reacts into an opaque carbonaceous product at 4-25 GPa. At pressures >- 27 GPa, the reaction product consists of an amorphous optically transparent solid and nitrogen (N2) in the solid phase. While not a one-to-one comparison due to the small time and length scales, the HP AIMD simulations show that some of the product is molecular N2, in qualitative agreement with experiment, while above 20 GPa most of the product consists of large amorphous CxHyNzOk clusters. Clustering is enhanced with pressure and reduces with temperature. In the experiments with initial sample pressure >- 25 GPa, the pressure within the DAC decreases with minimal change in DAC cavity area. At initial sample pressures of 43.9 GPa, when quenched to 0 K, simulations predict a product experiencing a lower pressure consistent with the experimental measurement at lower load pressures. The results are important for understanding the HP deflagration chemistry of LLM-105.