Unrevealing the phase transition of high-performing high-nitrogen energetic material 1,5-diaminotetrazole-4: N-oxide via first-principles studies

The effect of pressure on crystal structures, electronic properties, hydrogen bonds, optical properties and mechanical features of high-performing energetic material 1,5-diaminotetrazole-4: N-oxide was investigated by high-precision DFT-D method. The results reveal that there exists a critical point of phase transition around 8 GPa, reflected in various properties of the crystal. Band gap decreases gradually as the pressure increases, illustrating electrons are easier to transit from occupied orbit to the empty. The DOS analysis indicates that C-NH₂, N-NH₂ and N = O bonds may play a role as a reaction channel for the initial decomposition under high pressures. The hydrogen bond analysis indicates that pressure can alter the distribution of hydrogen bond in the crystal and modify the physicochemical properties. The absorption spectra of the crystal under high-pressure conditions show several strong bands in UV–visible region. The analysis on mechanical properties reveals that pressure can effectively improve the rigidity, plasticity and ductility for the crystal. Our results clarify the effect of pressure on energetic materials and are conducive to find the new crystalline phases for energetic materials.