High pressure-temperature polymorphism of 1,1-diamino-2,2-dinitroethylene

[摘要] 1,1-diamino-2,2-dinitroethylene (FOX-7) is a low sensitivity 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 (α, β, and γ). In this study, we have investigated the high pressure-temperature stability of FOX-7 polymorphs using synchrotron mid-infrared (MIR) spectroscopy. At ambient pressure, our MIR spectra and corresponding differential scanning calorimetry (DSC) measurements confirmed the known α → β (∼110 °C) and α → β (∼160 °C) structural phase transitions; as well as, indicated an additional transition γ → (∼210 °C), with the δ phase being stable up to ∼251 °C prior to decomposition. In situ MIR spectra obtained during isobaric heating at 0.9 GPa, revealed a potential α → β transition that could occur as early as 180 °C, while β → β+δ phase transition shifted to ∼300 °C with suppression of γ phase. Decomposition was observed slightly above 325 °C at 0.9 GPa.

[发布机构] Shock and Detonation Physics Group, Los Alamos National Laboratory, Los Alamos; NM; 87545, United States^1;Department of Chemistry, University of Alabama at Birmingham, Birmingham; AL; 35294, United States^2;Los Alamos Neutron Science Center, Los Alamos National Laboratory, Los Alamos; NM; 87545, United States^3;Geophysical Laboratory, Carnegie Instiution of Washington, 5251 Broad Branch Road NW, Washington; DC; 20015-1305, United States^4;High Explosives Science and Technology Group, Los Alamos National Laboratory, Los Alamos; NM; 87545, United States^5;Department of Physics, University of Alabama at Birmingham, Birmingham; AL; 35294, United States^6

[关键词] Ambient pressures;Gamma phase;High pressure;Isobaric heating;Low sensitivity;Mid-infrared spectroscopy;Secondary explosive;Structural phase transition