Synthesis, characterization and thermal decomposition behavior of a novel HNTO/AN co-crystal as a promising rocket propellant oxidizer

A novel energetic co-crystal composed of hydrazine 3-nitro-1,2,4-triazol-5-one (HNTO) and ammonium nitrate (AN) was successfully synthesized by solvent evaporation method. The formation of the co-crystal was confirmed by using scanning electron microscopy (SEM), powder X-ray diffraction (XRD), infrared and Raman spectroscopies. Compared to pure HNTO and AN, the manufactured highly dense energetic co-crystal crystalized into a new polymorphic form and exhibited a reduced sensitivity to friction and impact. Furthermore, the differential scanning calorimetry (DSC) analysis showed the absence of all temperature-dependent phases of AN in the new co-crystal. The kinetic investigation carried out by the isoconversional methods revealed that the apparent activation energy of decomposition of the HNTO/AN co-crystal is situated between those of its pure components. Compared to AN, the known propellant oxidizer, the obtained energetic co-crystal may be considered as a potential oxidizer for composite solid propellant formulations.