Experimental and theoretical study on polymorphism and phase transitions of hydrazine nitrate under high temperature and high pressure

Hydrazine Nitrate (HN) N₂H₄HNO₃ is one of the promising solid propellants for replacing ammonium perchlorate (AP) with low signature and low pollution. It can also be used as liquid high explosive (HE) and lead-free primary HE in commercial detonators. Although detonation and other physical chemical properties of HN have been investigated. Effects of pressure and temperature on structural stabilities are unknown. We carried out experiments of isobaric heating and isothermal compressing, using thermal stage at ambient pressure, diamond anvil cells (DAC) at high pressure and micro-Raman spectroscopy. Density functional theory and analysis of weak interactions were also employed for HN. Phase transitions triggered by temperature and pressure were observed. The present results provide phase diagram of HN to 8 GPa and 200^oC.