Anisotropic Impact Sensitivity and Shock Induced Plasticity of TKX-50 (Dihydroxylammonium 5,5′-bis(tetrazole)-,1′-diolate) Single Crystals: From Large-Scale Molecular Dynamics Simulations
Dihydroxylammonium 5,5′-bis(tetrazole)-1,1′-diolate (TKX-50) is a newly synthesized energetic material with high energy storage, low impact sensitivity, and low toxicity. These features make it a viable candidate to replace such commonly used energetic materials as RDX and CL-20 in the next generation of explosives. Sensitivity determines the engineering application of energetic materials (EMs) and has been widely studied for various EMs. To understand the origin of the anisotropic sensitivity and properties of this new synthesized EM, we report a flexible classical force field for TKX-50 developed to reproduce the molecular properties (geometry, vibrational frequencies and torsion barriers) and the crystal properties (cell parameters and lattice energy). We then used this force field in molecular dynamics (MD) simulations to predict such thermodynamic and mechanical properties as isothermal compressibility, thermal expansion, elastic moduli, and heat capacity. Furthermore, we carried out large scale (∼a half million atoms) MD simulations to investigate the mechanical response to shocks in the ,  and  directions. The predicted Hugoniot elastic limits (HELs) are 6.1 GPa for , 14.2 GPa for  and 9.1 GPa for  shocks. Thus, single crystal TKX-50 shows anisotropic impact sensitivity with  as the most sensitive direction and  as least sensitive. The plastic deformations in shock compression along the  direction primary arise from the (001)/ and (010)/ slip systems of. For the  shock, the primary slip systems are (100)/ and (001)/. However, no obvious slip system was observed for  shock.
© 2014 American Chemical Society. ACS AuthorChoice - This is an open access article published under an ACS AuthorChoice License, which permits copying and redistribution of the article or any adaptations for non-commercial purposes. Received: October 31, 2014. Revised: December 23, 2014. Publication Date (Web): December 29, 2014. We thank Al Stern and Cliff Bedford for suggesting the importance of characterizing TKX-50. This research was funded by ONR (N00014-09-1-0634, Cliff Bedford).
Published - jp510951s.pdf
Supplemental Material - jp510951s_si_001.pdf