New Assembly of Acetamidinium Nitrate Modulated by High Pressure

Abstract

High pressure is an essential thermodynamic parameter in exploring the performance of condensed energetic materials. Combination of high-pressure techniques and supramolecular chemistry opens a new avenue for synthesis of high energy density materials. Herein, we fabricate a new high-pressure-assisted assembly of energetic material acetamidinium nitrate (C₂N₂H₇⁺·NO₃^–, AN) with <i>P</i>-1 symmetry after a 0–12 GPa–0 treatment at room temperature, which exhibits a density that is 9.8% higher than that of the initial <i>P</i>2₁/<i>m</i> phase. Evolution of intermolecular lattice modes in Raman spectra and synchrotron X-ray diffraction (XRD) patterns provide strong evidence for this transition in the 1.3–3.4 GPa range. The mechanism involves relative motions between ionic pairs in the hydrogen-bonded array and distortions of building blocks