Decompression-Induced Chemical Reaction in CL-20

Energetic materials have closely correlated safety and high-pressure chemical reaction kinetics. While extensive research has typically focused on structural evolution and reversible phase transitions at high pressures, chemical decomposition pathways remain underexplored. Here, we report a novel pressure-induced chemical reaction in CL-20 during decompression from a peak pressure of 26.2 GPa under nonhydrostatic compression. Infrared spectroscopy confirmed chemical bond cleavage, yielding gaseous decomposition products primarily composed of N₂O and CO₂. Molecular dynamics simulations revealed that the initial decomposition steps involved H migration, OH transfer, β-scission of the C-C bridge, and cleavage of C-N bonds. Notably, under improved hydrostatic conditions (using KBr as the pressure-transmitting medium), the reaction threshold pressure increased to 30.1 GPa, highlighting the critical roles of shear stress in the diamond anvil cell environment. This study represents the first clear demonstration of decompression-induced chemical reactions in condensed explosives, providing fundamental insights into their intrinsic safety mechanisms as well as their initiation and detonation behaviors.