High pressure–temperature phase diagram of 1,1-diamino-2,2-dinitroethylene (FOX-7)

Journal Article · Thu Aug 27 00:00:00 EDT 2015 · Journal of Physical Chemistry. A, Molecules, Spectroscopy, Kinetics, Environment, and General Theory

DOI:https://doi.org/10.1021/acs.jpca.5b07811· OSTI ID:1247670

Bishop, Matthew M. ^[1]; Velisavljevic, Nenad ^[2]; Chellappa, Raja ^[2]; Vohra, Yogesh K. ^[3]

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1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Univ. of Alabama at Birmingham, Birmingham, AL (United States)
2. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
3. Univ. of Alabama at Birmingham, Birmingham, AL (United States)

The pressure–temperature (P–T) phase diagram of 1,1-diamino-2,2-dinitroethylene (FOX-7) was determined by in situ synchrotron infrared radiation spectroscopy with the resistively heated diamond anvil cell (DAC) technique. The stability of high-P–T FOX-7 polymorphs is established from ambient pressure up to 10 GPa and temperatures until decomposition. The phase diagram indicates two near isobaric phase boundaries at ~2 GPa (α → I) and ~5 GPa (I → II) that persists from 25 °C until the onset of decomposition at ~300 °C. In addition, the ambient pressure, high-temperature α → β phase transition (~111 °C) lies along a steep boundary (~100 °C/GPa) with a α–β–δ triple point at ~1 GPa and 300 °C. A 0.9 GPa isobaric temperature ramping measurement indicates a limited stability range for the γ-phase between 0.5 and 0.9 GPa and 180 and 260 °C, terminating in a β–γ–δ triple point. With increasing pressure, the δ-phase exhibited a small negative dT/dP slope (up to ~0.2 GPa) before turning over to a positive 70 °C/GPa slope, at higher pressures. The decomposition boundary (~55 °C/GPa) was identified through the emergence of spectroscopic signatures of the characteristic decomposition products as well as trapped inclusions within the solid KBr pressure media.

• Research Organization: Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Univ. of Alabama, Birmingham, AL (United States); Carnegie Institution of Washington, Washington, D.C. (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA)
• Grant/Contract Number: AC52-06NA25396; NA0002014; NA0002006
• OSTI ID: 1247670
• Alternate ID(s): OSTI ID: 1251192; OSTI ID: 1335458
• Report Number(s): LA-UR-15-26331
• Journal Information: Journal of Physical Chemistry. A, Molecules, Spectroscopy, Kinetics, Environment, and General Theory, Vol. 119, Issue 37; ISSN 1089-5639
• Publisher: American Chemical Society
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
high pressure
infrared spectroscopy
phase diagram
high explosive
hydrogen bonding
36 MATERIALS SCIENCE