The effects of H+, NH3OH+ and NH4+ on the thermal decomposition of bistetrazole N-oxide anion

Abstract

The bistetrazole N-oxide energetic ionic salt dihydroxylammonium 5,5′-bistetrazole-1,1′-diolate (TKX-50) has attracted great interest as it breaks through the limitations of the traditional nitro group, high detonation velocity and moderate impact sensitivity. Reports show that TKX-50 transforms into the 5,5′-bis(2-hydroxytetrazole) (BTO) precursor, which is further decomposed and partly converted to diamino 5,5′-bistetrazole-1,1′-diolate (ABTOX). Studying the effects of H⁺, NH₃OH⁺ and NH₄⁺ on the thermal decomposition mechanism of bistetrazole N-oxide anion would provide a more comprehensive understanding of the TKX-50 decomposition mechanism. Herein, TKX-50, BTO and ABTOX decomposition rates, on-line analysis of the gas products, as well as quantitative analysis, are presented. It was found that the presence of two H⁺ decreases the decomposition temperature, whereas NH₃OH⁺ greatly increases the decomposition rate. In the presence of NH₃OH⁺, the bistetrazole N-oxide anion completely decomposes without producing C₂N₂; however, NH₄⁺ promotes the polymerization of C₂N₂ generated by the bistetrazole N-oxide anion, and the amount of NO produced is greater than that of N₂O. Therefore, in the TKX-50 decomposition process, the bistetrazole N-oxide anion does not receive two H⁺ simultaneously and converts into BTO. Furthermore, the competition between cations and their decomposition products for the H⁺ affects the degree of decomposition, which is important in understanding the energy release mechanism.