Reverse 15 N Kinetic Isotope Effect Amplifies the Energy Release of Ammonium Perchlorate

The energy release rate of ammonium perchlorate (AP) is crucial for the detonation performance of both composite explosives and propellant systems. This work systematically investigates how 15N-substitution influences the structure, thermal decomposition, and microdetonation properties of AP. Structural analyses reveal that while 15N-substitution preserves the crystal packing model, it induces a slight elongation of the 15N–H bonds and a marginal increase in crystal density. Thermal analysis shows that the fundamental decomposition pathway remains unchanged; however, the apparent activation energy is significantly reduced from 68.15 kJ/mol (raw AP) to 45.52 kJ/mol for 15N-AP. This reduction demonstrates a pronounced reverse kinetic isotope effect (KIE) on proton transfer between NH4+ and ClO4–, which accelerates low-temperature decomposition. Laser-driven shock wave tests further confirm that 15N-AP exhibits a higher initial shock wave velocity and enhanced energy release intensity. Collectively, these findings highlight 15N-substitution as a novel and effective strategy for modulating energy release, offering a promising approach to amplify the performance of energetic formulations via isotopic substitution engineering.