Reverse¹⁵N 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.