Pressure induced polymorphism in ammonium azide (NH4N3)

► Ammonium azide (NH4N3) studied at high pressures by Raman spectroscopy. ► Phase transition is observed at pressure ≈3 GPa. ► Strength of hydrogen bond appears to be modified at the phase transition. ► NH4N3 remain in molecular form up to pressures above 50 GPa.