High-Pressure Structural Response of an Insensitive Energetic Crystal: 1,1-Diamino-2,2-dinitroethene (FOX-7)

Journal Article · Tue Nov 15 00:00:00 EST 2016 · Journal of Physical Chemistry. C

DOI:https://doi.org/10.1021/acs.jpcc.6b10010· OSTI ID:1476723

Dreger, Zbigniew A. ^[1]; Stash, Adam I. ^[2]; Yu, Zhi-Gang ^[1]; Chen, Yu-Sheng ^[3]; Tao, Yuchuan ^[1]; Gupta, Yogendra M. ^[1]

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1. Washington State Univ., Pullman, WA (United States). Inst. for Shock Physics. Dept. of Physics and Astronomy
2. Karpov Inst. of Physical Chemistry, Moscow (Russian Federation). State Scientific Center of Russian Federation
3. Univ. of Chicago, Argonne, IL (United States). Advance Photon Source. ChemMatCARS

Here, high-pressure structural response of an insensitive energetic crystal—1,1-diamino-2,2-dinitroethene (FOX-7)—was examined to gain insight into its structural and chemical stability and to obtain isothermal compression data. Using synchrotron single-crystal X-ray diffraction measurements, details of pressure-induced structural changes to 12.8 GPa were determined across three FOX-7 phases: α (P2₁/n), α' (P2₁/n), and ε (P1). We found that the C–NO₂ bond is the most compressible chemical bond, and high pressure significantly reduces and homogenizes the length of H bonds in the hydrogen-bond network. The α'-ε phase transition, at 4.5 GPa, significantly affects all molecular and crystal properties, whereas the α–α' transition, at 2 GPa, is associated with subtle molecular and intermolecular changes. Anisotropic compressibility was observed over the entire pressure range, consistent with the layered structure of the crystal. The equation-of-state parameters were obtained using the third-order Birch–Murnaghan equation below and above the α'-ε phase transition. It is shown that dispersion-corrected DFT-D calculations reproduce well pressure-induced changes in the unit cell parameters. Finally, the findings of this work provide new insights into the molecular and structural mechanisms governing the high-pressure stability/insensitivity of insensitive energetic crystals.

• Research Organization: Washington State Univ., Pullman, WA (United States); Univ. of Chicago, Argonne, IL (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA); USDOE Office of Science (SC); Office of Naval Research (ONR) (United States); National Science Foundation (NSF)
• Grant/Contract Number: NA0002007; AC02-06CH11357; N000014-16-1-2088; CHE-1346572
• OSTI ID: 1476723
• Journal Information: Journal of Physical Chemistry. C, Vol. 120, Issue 48; ISSN 1932-7447
• Publisher: American Chemical Society
• Country of Publication: United States
• Language: English

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37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY