Understanding the Correlation between Impact Sensitivity and Elasticity of Energetic Crystals via Dispersion-Corrected Density Functional Theory Calculations

Impact
sensitivity and elasticity are among the most important
properties of energetic materials. Both properties are related to
the mechanical stress. Understanding elasticity and impact sensitivity
is crucial for predicting the mechanical response and failure of energetic
materials, thus establishing a correlation between the elasticity
mechanics and the initiation and detonation of energetic materials.
However, it is unclear how elasticity influences the impact sensitivity
of energetic crystals. Herein, the elastic properties of 19 typical
energetic crystals with impact sensitivity varying from low to high
are studied by using dispersion-corrected density functional theory.
We demonstrate that the elastic stiffness tensors predicted in this
work satisfy the necessary and sufficient stability conditions for
elastic stability. A thorough comparison with literature data further
shows that while the results are in general agreement with literature
data, large discrepancies are found for certain elastic tensor elements.
By probing the correlation between impact sensitivity and elasticity,
we show that higher elastic moduli and elastic anisotropy generally
lead to lower impact sensitivity. The underlying mechanism is that
higher elastic moduli and higher elastic anisotropy lead to easy absorption
of impact energy in the form of elastic deformation and dissipation
of impact energy through thermal conductivity and shear sliding, thus
lowering the probability of impact-induced formation and growth of
hotspots. These findings facilitate our fundamental understanding
of the elastic properties and structure–property relationships
of energetic crystals.