Exploration of the Hydrogen-Bonded Energetic Material Carbohydrazide at High Pressures

Abstract

We have reported the high-pressure behavior of hydrogen-bonded energetic material carbohydrazide (CON₄H₆, CHZ) via <i>in situ</i> Raman spectroscopy and angle-dispersive X-ray diffraction (ADXRD) in a diamond anvil cell with ∼15 GPa at room temperature. Significant changes in Raman spectra provide evidence for a pressure-induced structural phase transition in the range of ∼8 to 10.5 GPa. ADXRD experiments confirm this phase transition by symmetry transformation from <i>P</i>2₁/<i>n</i> to a possible space group <i>P</i>1̅, which exhibits ∼23.1% higher density at 10.1 GPa compared to phase <i>P</i>2₁/<i>n</i> at ambient pressure. Moreover, the observed transition is completely reversible when the pressure is totally released. On the basis of the decreased number of hydrogen bonds, the shortened hydrogen bond lengths, and the variations in the NH and NH₂ stretching Raman peaks in the high-pressure phase, we propose that this phase transition is caused by the rearrangement of the hydrogen-bonded networks