High Pressure-Temperature Phase Diagram of 1,1-diamino-2,2-dinitroethylene

ORAL

Abstract

1,1-diamino-2,2-dinitroethelyne (FOX-7) is a less sensitive energetic material with performance comparable to commonly used secondary explosives such as RDX and HMX. At ambient pressure, FOX-7 exhibits complex polymorphism with at least three structurally distinct phases ($\alpha $, \quad $\beta $, and $\gamma )$. In this study, we have investigated the high P-T stability of FOX-7 polymorphs using synchrotron mid-infrared (MIR) spectroscopy. At ambient pressure, our MIR spectra confirmed the known $\alpha \quad \to \quad \beta $ (110 $^{\circ}$C) and $\beta \quad \to \quad \gamma $ (160 $^{\circ}$C) phase transitions; as well as, indicated an additional phase transition, $\gamma \quad \to \quad \delta $ (210$^{\circ}$C), with the $\delta $ phase being stable up to 250 $^{\circ}$C prior to melt/decomposition. In situ MIR spectra obtained during isobaric heating at 0.9 GPa revealed that the $\alpha \quad \to \quad \beta $ transition occurs at 180$^{\circ}$C, while $\beta $ $\to \quad \beta +\delta $ phase transition shifted to 300$^{\circ}$C with suppression of $\gamma $ phase. Decomposition was observed above 325$^{\circ}$C. Based on multiple high P-T measurements, we have established the first high P-T phase diagram of FOX-7.

*This work was, in part, supported by the US DOE under contract No. DE-AC52-06NA25396 and Science Campaign 2 Program. MB acknowledges additional support from the NSF BD program. Use of NSLS (DE-AC02-98CH10886) beamline U2A (COMPRES, No.EAR01-35554, CDAC).

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Authors

  • Matthew Bishop

    • Los Alamos National Laboratory

  • Raja Chellappa

    • Los Alamos National Laboratory

  • Zhenxian Liu

    • Geophysical Laboratory, Carnegie Institution of Washington
    • Brookhaven National Laboratory
    • Geophysical Laboratory, Carnegie Institution of Washington, 5251 Broad Branch Road NW, Washington D.C. 20015, USA
    • Carnegie Institution of Washington

  • Daniel Preston

    • LANL
    • Los Alamos National Laboratory

  • Mary M. Sandstrom

    • Los Alamos National Laboratory
    • LANL

  • Dana Dattelbaum

    • Los Alamos National Laboratory
    • Shock and Detonation Physics (WX-9), Los Alamos National Laboratory
    • Los Alamos National Lab

  • Yogesh Vohra

    • University of Alabama at Birmingham
    • Deaprtment of Physics, University of Alabama at Birmingham (UAB)
    • Dept. of Physics, University of Alabama at Birmingham

  • Nenad Velisavljevic

    • Los Alamos National Laboratory