High-Pressure Structural Response of an Insensitive Energetic Crystal: Dihydroxylammonium 5,5′-Bistetrazole-1,1′-diolate (TKX-50)

Abstract

The structural response of a novel, insensitive energetic crystal—dihydroxylammonium 5,5′-bistetrazole-1,1′-diolate (TKX-50)—was examined under high pressure. Using synchrotron single-crystal X-ray diffraction measurements, details of molecular, intermolecular, and crystal changes were determined to ∼10 GPa to understand its structural stability. The experimental results showed that TKX-50 exhibits highly anisotropic compression and significantly lower volume compressibility than currently known energetic crystals. These results are found to be in general agreement with our previous predictions from the DFT calculations. Additionally, the experimental data revealed anomalous compression—an expansion of the unit cell along the a axis (negative linear compressibility, NLC) upon compression to ∼3 GPa. The structural analyses demonstrated that this unusual effect, the first such observation in an energetic crystal, is a consequence of the highly anisotropic response of 3D motifs, comprised of two parallel ani...